Optical device and light emitting device

Abstract

An optical device of one embodiment includes a structure that can output light of a short wavelength region such as a visible region. The optical device includes a UC layer, a first light confinement layer, a second light confinement layer, and a resonant mode formation layer. The UC layer includes an up-conversion material that receives excitation light of a first wavelength region and outputs light of a second wavelength region shorter than the first wavelength region. The first light confinement layer has a light reflection property of reflecting at least part of the light of the second wavelength region. The second light confinement layer has a light reflection property of reflecting part of the light of the second wavelength region and transmitting the remaining part, and is arranged with the UC layer positioned between the first and second light confinement layers. The resonant mode layer is provided between the UC layer and the first light confinement layer or between the UC layer and the second light confinement layer, includes a base layer and a plurality of different refractive index regions, and forms a resonant mode of the light of the second wavelength region.

Description

Technical Field

[0001] This invention relates to optical devices and light-emitting devices.

[0002] This application claims priority to Japanese Patent Application No. 2020-094937, filed on May 29, 2020, the contents of which are incorporated herein by reference in their entirety. Background Technology

[0003] Patent Document 1 discloses a technology relating to a semiconductor light-emitting device. This semiconductor light-emitting device includes: a first conductivity type semiconductor layer and a second conductivity type semiconductor layer disposed on a main surface of a substrate; an active layer sandwiched between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer and generating light when injected with charge carriers; a two-dimensional diffraction lattice disposed on a reference plane parallel to the main surface of the substrate, defining the wavelength of the light to be generated in the active layer; and a light-emitting surface disposed parallel to the main surface of the substrate and emitting the light generated in the active layer. The two-dimensional diffraction lattice, for example, has a portion with a second refractive index disposed in such a way that it forms a two-dimensional diffraction lattice within a medium having a first refractive index, wherein the first refractive index is greater than the second refractive index. The two-dimensional diffraction lattice is, for example, either a triangular lattice or a square lattice.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2000-332351

[0007] Non-patent literature

[0008] Non-patent literature 1: Jing Zhou et al., "Upconversion Luminescent Materials: Advances and Applications", Chemical Reviews, 115, pp. 395-465, (2015)

[0009] Non-patent document 1: Y.Kurosaka et al., "Effects of non-lasing band in two-dimensional photonic-crystal lasers clarified using omnidirectional bandstructure," Opt.Express 20, 21773-21783 (2012) Summary of the Invention

[0010] The technical problem that the invention aims to solve

[0011] The inventors studied the aforementioned prior art and, as a result, discovered the following technical problem. Specifically, in surface-emitting light-emitting elements that output laser light in a direction intersecting the main surface of the substrate, the layer forming the resonant mode in the direction along the main surface of the substrate (e.g., a photonic crystal layer, hereinafter referred to as the "PC layer") is sometimes disposed near the active layer. However, in relatively short wavelength regions, such as the green or blue regions, it is currently impossible to realize a practical photonic crystal surface-emitting laser or a phase-modulated light-emitting element (Static-iPMSEL).

[0012] Specifically, in the case of light-emitting elements primarily comprising GaAs-based semiconductors, their emission wavelengths are, for example, in the near-infrared region, achieving light-emitting elements with practical light output characteristics (e.g., low threshold current values). However, in the case of light-emitting elements primarily comprising nitride semiconductors such as GaN, although their emission wavelengths are, for example, in the green to blue region, the light confinement coefficient of the layer forming the resonant mode is too small due to the material properties. Therefore, a photonic crystal surface-emitting laser or phase-modulated light-emitting element with practical light output characteristics has not yet been realized. To enrich the color display in the visible region, it is desirable to realize a practical photonic crystal surface-emitting laser or phase-modulated light-emitting element capable of emitting light in wavelengths shorter than the red region, such as those in the green to blue region.

[0013] The present invention was made to solve the aforementioned technical problems, and its object is to provide an optical device for a practical photonic crystal surface-emitting laser or phase-modulated light-emitting element capable of emitting light in a relatively short wavelength region, such as the green or blue region, and a light-emitting device including the optical device. As an example, the object is to provide a light-emitting device in which the aforementioned optical device is applied to a photonic crystal surface-emitting laser or phase-modulated light-emitting element as an excitation source.

[0014] Technical means to solve the problem

[0015] The optical device of the present invention includes an upconversion layer (hereinafter referred to as the "UC layer"), a first optical confinement layer (a multilayered light-reflecting layer or a single layer), a second optical confinement layer (a multilayered light-reflecting layer or a single layer), and a resonant mode forming layer. The UC layer comprises an upconversion material that receives excitation light contained in a first wavelength region and outputs light in a second wavelength region shorter than the first wavelength region. The first optical confinement layer has light-reflecting properties that reflect at least a portion of the light in the second wavelength region. The second optical confinement layer has light-reflecting properties that reflect a portion of the light in the second wavelength region while allowing the remainder to pass through. Furthermore, the second optical confinement layer is configured such that the UC layer is located between the first and second optical confinement layers. That is, the second optical confinement layer is disposed on the opposite side of the first optical confinement layer relative to the UC layer. The resonant mode forming layer is disposed between the first and UC layers, or between the second and UC layers. The resonant mode layer comprises: a base layer; and multiple regions with different refractive indices, having a different refractive index than the base layer, and distributed in a two-dimensional manner on a reference plane perpendicular to the thickness direction of the resonant mode forming layer. Thus, the resonant mode forming layer forms a resonant mode of light in the second wavelength region along the reference plane.

[0016] The effects of the invention

[0017] According to the light-emitting device of the present invention, a practical photonic crystal surface-emitting laser and the like can be provided that can output light in a relatively short wavelength region, such as the visible region. Attached Figure Description

[0018] Figure 1 This is a diagram showing the cross-sectional structure of the light-emitting device according to the first embodiment.

[0019] Figure 2 This is a top view of the PC layer.

[0020] Figure 3 (a)~ Figure 3 (g) is a figure (1) showing examples of the shapes of regions with different refractive indices.

[0021] Figure 4 (a)~ Figure 4 (k) is a figure (2) showing examples of the shapes of regions with different refractive indices.

[0022] Figure 5 (a)~ Figure 5 (k) is a figure (3) showing examples of the shapes of regions with different refractive indices.

[0023] Figure 6 This is a diagram showing the cross-sectional structure of the light-emitting device according to the second embodiment.

[0024] Figure 7 This is a top view of the phase modulation layer.

[0025] Figure 8 This is a magnified representation of a portion of the phase modulation layer.

[0026] Figure 9 It is a diagram used to illustrate the relationship between the optical image obtained by imaging the output beam pattern of an optical device and the rotation angle distribution in the phase modulation layer.

[0027] Figure 10 It is a diagram used to illustrate the coordinate transformation from spherical coordinates to the XYZ rectangular coordinate system.

[0028] Figure 11 This indicates that it is applied only within a specific region of the phase modulation layer. Figure 7 A top view of an example of a refractive index structure.

[0029] Figure 12 (a) and Figure 12 (b) is a diagram illustrating points to note when using the common Discrete Fourier Transform (or Fast Fourier Transform) for calculations when determining the configuration of different refractive index regions.

[0030] Figure 13 (a)~ Figure 13 (d) is a diagram showing an example of the beam pattern (optical image) output from a GaAs-based S-iPM laser in the near-infrared band.

[0031] Figure 14 This is a top view of the phase modulation layer, which serves as the resonant mode forming layer, in the optical device of the third embodiment.

[0032] Figure 15 It is a diagram showing the positional relationship of different refractive index regions in the phase modulation layer.

[0033] Figure 16 This is a diagram showing the cross-sectional structure of the light-emitting device in the first modified example.

[0034] Figure 17 This is a cross-sectional view showing the manufacturing process of the light-emitting device in the second modified example.

[0035] Figure 18 This is a diagram showing the cross-sectional structure of the light-emitting device in the third modified example.

[0036] Figure 19 This is a diagram showing the cross-sectional structure of the light-emitting device in the fourth variation.

[0037] Figure 20 This is a cross-sectional view showing the manufacturing process of the light-emitting device in the fifth modified example.

[0038] Figure 21This is a diagram showing the cross-sectional structure of the light-emitting device in the sixth modified example.

[0039] Figure 22 This is a diagram showing the cross-sectional structure of the light-emitting device in the seventh modified example.

[0040] Figure 23 This is a diagram showing the cross-sectional structure of the light-emitting device in the 8th modified example.

[0041] Figure 24 This is a top view representing the inverted lattice space of the PC layer of a PCSEL oscillating at point Γ.

[0042] Figure 25 It is a three-dimensional observation Figure 24 The diagram shows a three-dimensional representation of the inverted lattice space.

[0043] Figure 26 This is a top view showing the inverted lattice space of the PC layer of a PCSEL oscillating at point M.

[0044] Figure 27 This is a top view showing the inverted lattice space of the phase modulation layer of an S-iPM laser oscillating at point Γ.

[0045] Figure 28 It is a three-dimensional observation Figure 13 The diagram shows a three-dimensional representation of the inverted lattice space.

[0046] Figure 29 This is a top view showing the inverted lattice space of the phase modulation layer of an S-iPM laser oscillating at point M.

[0047] Figure 30 It is a conceptual diagram used to illustrate the operation of applying a diffraction vector with a certain magnitude and orientation to the surface wavenumber vector.

[0048] Figure 31 It is a diagram used to schematically illustrate the surrounding structure of a light line.

[0049] Figure 32 This is a diagram that conceptually represents an example of the distribution of rotation angles.

[0050] Figure 33 This is a diagram showing an example of the rotation angle distribution of the phase modulation layer.

[0051] Figure 34 It is Figure 33 The diagram shows a magnified representation of part S.

[0052] Figure 35 Indicates from having Figure 33 The diagram shows the beam pattern (optical image) output by a semiconductor light-emitting element with a rotational angle distribution.

[0053] Figure 36 yes Figure 35 A schematic diagram of the beam pattern shown.

[0054] Figure 37 (a) is a schematic diagram of the beam pattern. Figure 37 (b) is a diagram showing the phase distribution of the beam pattern.

[0055] Figure 38 (a) is a schematic diagram of the beam pattern. Figure 38 (b) is a diagram showing the phase distribution of the beam pattern.

[0056] Figure 39 (a) is a schematic diagram of the beam pattern. Figure 39 (b) is a diagram showing the phase distribution of the beam pattern.

[0057] Figure 40 This is a schematic diagram used to explain the cross-sectional structure of the light-emitting device of the fourth embodiment while comparing it with the light-emitting device of the first embodiment.

[0058] Figure 41 This diagram illustrates the manufacturing process of the excitation light source (light source unit) in the first manufacturing method (unit assembly type) of the light-emitting device according to the fourth embodiment.

[0059] Figure 42 (a) and Figure 42 (b) is a diagram illustrating the installation process of the excitation light source onto the base in the first manufacturing method.

[0060] Figure 43 (a) and Figure 43 (b) is a diagram illustrating the manufacturing process of the optical device (resonator section) in the first manufacturing method. Figure 43 (c) is a diagram illustrating the mounting process of an optical device onto a base on which an excitation light source has been mounted in the first manufacturing method.

[0061] Figure 44 (a) is a top view of a light-emitting device manufactured by the first manufacturing method (unit assembly type). Figure 44 (b) is along Figure 44 (a) is a cross-sectional view of the light-emitting device shown by arrow II.

[0062] Figure 45 (a) is a cross-sectional view of a light-emitting device having a light-confining layer of the first structure manufactured by the first manufacturing method. Figure 45 (b) is a cross-sectional view of a light-emitting device having a light-confining layer of the second structure manufactured by the first manufacturing method.

[0063] Figure 46(a) is a cross-sectional view of a light-emitting device having a light-confining layer of the third structure manufactured by the first manufacturing method. Figure 46 (b) is a cross-sectional view of a light-emitting device having a light-confining layer of the fourth structure manufactured by the first manufacturing method.

[0064] Figure 47 This is a diagram used to illustrate the design principles of optical devices (resonator model).

[0065] Figure 48 It is about having Figure 47 The cross-sectional structure of the optical device is shown in the figure. Various hole shapes in the PC layer are represented by curves showing the relationship between Fourier coefficients and FF values.

[0066] Figure 49 (a) and Figure 49 (b) indicates that the diffraction intensity κ can be increased respectively. 2，0 and distribution ratio Γ UC An example of a cross-sectional structure, Figure 49 (c) is for Figure 49 (a) and Figure 49 (b) shows the cross-sectional structure of the optical device, representing the diffraction intensity κ. 2，0 and distribution ratio Γ UC The table of calculation results Figure 49 (d) and Figure 49 (e) is a diagram used to illustrate the shape of the hole used in the calculation.

[0067] Figure 50 (a) shows an example of the cross-sectional structure of an optical device prepared for studying the thickness dependence of the UC layer. Figure 50 (b) indicates the shape of the hole used in the study. Figure 50 (c)~ Figure 50 (f) represents the diffraction intensity κ. 2，0 Distribution ratio Γ PC Distribution ratio Γ UC and effective refractive index n eff A table showing the calculation results for each.

[0068] Figure 51 It is for those who have Figure 50 (a) shows the optical device with the cross-sectional structure shown in the table, which summarizes the dependence of the thickness of the light confinement layer on the thickness of the PC layer.

[0069] Figure 52 (a) shows an example of the cross-sectional structure of an optical device prepared for research. Figure 52 (b)~ Figure 52 (e) represents the diffraction intensity κ. 2，0 Distribution ratio Γ PC Distribution ratio ΓUC and effective refractive index n eff A table showing the calculation results for each.

[0070] Figure 53 (a) is a cross-sectional view of a light-emitting device having a light-confining layer of the first structure, manufactured by the second manufacturing method (upconversion material injection type) of the light-emitting device according to the fourth embodiment. Figure 53 (b) is a cross-sectional view of a light-emitting device having a light-confining layer of the second structure manufactured by the second manufacturing method.

[0071] Figure 54 (a) is a cross-sectional view of a light-emitting device having a light-confining layer of the third structure manufactured by the second manufacturing method. Figure 54 (b) is a cross-sectional view of a light-emitting device having a light-confining layer of the fourth structure manufactured by the second manufacturing method.

[0072] Figure 55 (a)~ Figure 55 (d) is used as an example to illustrate. Figure 54 (a) is a diagram (1) showing the manufacturing process of a light-emitting device with a light-containment layer having a third structure.

[0073] Figure 56 (a)~ Figure 56 (d) is used as an example to illustrate. Figure 54 (a) is a diagram (2) showing the manufacturing process of a light-emitting device with a light-containment layer having a third structure.

[0074] Figure 57 (a)~ Figure 57 (d) is used as an example to illustrate. Figure 54 (a) is a diagram (3) showing the manufacturing process of a light-emitting device with a light-containment layer having a third structure.

[0075] Figure 58 (a)~ Figure 58 (d) is used as an example to illustrate. Figure 54 (a) is a diagram (4) showing the manufacturing process of a light-emitting device with a light-containment layer having a third structure. Detailed Implementation

[0076] [Description of embodiments of the present invention]

[0077] First, the embodiments of the present invention will be described individually.

[0078] (1) As one embodiment of this invention, the optical device includes a UC layer (upconversion layer), a first light confinement layer (reflective layer or single layer), a second light confinement layer (reflective layer or single layer), and a resonant mode forming layer. The UC layer contains an upconversion material that receives excitation light contained in a first wavelength region and outputs light in a second wavelength region shorter than the first wavelength region. The first light confinement layer has light reflection characteristics that reflect at least a portion of the light in the second wavelength region. The second light confinement layer has light reflection characteristics that reflect a portion of the light in the second wavelength region while allowing the remainder to pass through. Furthermore, the second light confinement layer is configured such that the UC layer is located between the first light confinement layer and the second light confinement layer. That is, the second light confinement layer is disposed on the opposite side of the first light confinement layer relative to the UC layer. The resonant mode forming layer is disposed between the first light confinement layer and the UC layer, or between the second light confinement layer and the UC layer. The resonant mode layer comprises: a base layer; and multiple regions with different refractive indices, having a different refractive index than the base layer, and distributed in a two-dimensional manner on a reference plane perpendicular to the thickness direction of the resonant mode forming layer. Thus, the resonant mode forming layer forms a resonant mode of light in the second wavelength region along the reference plane.

[0079] Upconversion materials are materials that convert low-energy light of long wavelengths, such as near-infrared light, into high-energy light of shorter wavelengths. In this optical device, when the UC layer receives excitation light contained in a first wavelength region (e.g., the near-infrared region), light in a second wavelength region (e.g., the visible region such as red, green, or blue regions) shorter than the first wavelength region is generated in the UC layer. This light in the second wavelength region is confined between the first and second light-confining layers and undergoes diffraction based on the resonant mode forming layer. In the resonant mode forming layer, resonant modes are formed in a predetermined direction (in-plane direction) perpendicular to the thickness direction of the resonant mode forming layer, generating laser modes corresponding to the configuration of multiple regions with different refractive indices. The laser travels in the thickness direction of the resonant mode forming layer and is output to the outside of the optical device through the second light-reflecting layer.

[0080] Thus, according to the aforementioned optical device, it is possible to output a shorter wavelength laser based on a longer wavelength excitation light. Furthermore, since nitride semiconductors such as GaN are not required in the resonant mode forming layer, the material selection for the resonant mode forming layer is highly flexible. Therefore, it is also easy to improve the light confinement coefficient of the resonant mode forming layer. Therefore, the optical device according to the present invention provides a practical photonic crystal surface-emitting laser or phase-modulated light-emitting element (Static-iPMSEL) capable of outputting light in a shorter wavelength region, such as the visible region.

[0081] The first and second light-confining layers can each be either light-reflecting layers with a multilayer structure such as a dielectric multilayer film, or monolayers made of a single material having a substantially uniform refractive index distribution at least along the thickness direction of the light-confining layer (from the first light-confining layer toward the second light-confining layer) and a refractive index lower than that of the UC layer. Furthermore, a resonant mode forming layer can be embedded within or on the surface of the monolayer light-confining layer. Specifically, in the case where the second light-confining layer includes a resonant mode forming layer, as one aspect of the invention, the second light-confining layer has a base layer comprising a portion of the second light-confining layer facing the UC layer, and a monolayer structure having multiple recesses on this layer for defining multiple regions with different refractive indices.

[0082] (2) In one embodiment of this invention, where the second light confinement layer has a single-layer structure in which a resonant mode forming layer is embedded, the optical device also includes, similarly to the embodiment described above, a UC layer, a first light confinement layer (single layer), a second light confinement layer (reflective layer or single layer), and a resonant mode forming layer. The UC layer receives excitation light in a first wavelength region and outputs light in a second wavelength region shorter than the first wavelength region. The first light confinement layer has light reflection characteristics that reflect at least a portion of the light in the second wavelength region. The second light confinement layer has light reflection characteristics that reflect a portion of the light in the second wavelength region while allowing the remainder to pass through. Furthermore, the second light confinement layer is configured such that the UC layer is located between the first light confinement layer and the second light confinement layer, and has a single-layer structure in which a resonant mode of the light in the second wavelength region is formed therein. The resonant mode forming layer forms the resonant mode of the light in the second wavelength region. Specifically, the resonant mode forming layer includes: a base layer disposed on one side of the layer of the second light confinement layer facing the UC layer and constituting part of the second light confinement layer; and multiple regions with different refractive indices defined by multiple recesses distributed in a two-dimensional manner on the layer of the second light confinement layer and having a refractive index different from that of the base layer.

[0083] (3) As one aspect of the present invention, the resonant mode forming layer may also be a PC layer (photonic crystal layer) with multiple regions of different refractive indices arranged periodically. In this case, light in the second wavelength region output from the UC layer is confined between the first and second optical confinement layers and subjected to diffraction based on the PC layer. In the PC layer, a resonant mode is formed along a predetermined direction (in-plane direction) on a reference plane perpendicular to the thickness direction of the PC layer, and the light oscillates at a wavelength corresponding to the arrangement period of the multiple regions of different refractive indices, generating laser light. For example, in a cubic lattice crystal, if the arrangement period is one wavelength of light, a portion of the laser light is diffracted in the thickness direction of the PC layer and output to the outside of the optical device through the second light reflection layer. In addition to the PC layer, a phase modulation layer or the like can also be applied to the resonant mode forming layer.

[0084] (4) The optical device can also be an optical device that outputs an optical image (e.g., a phase-modulated light-emitting element). That is, as an embodiment of the present invention, in an imaginary square lattice set on a reference plane to which multiple different refractive index regions are to be formed, each of the multiple different refractive index regions is configured such that its centroid is separated from the corresponding lattice point in the lattice point of the imaginary square lattice, and the line segment connecting the centroid and the corresponding lattice point has a rotation angle relative to the imaginary square lattice corresponding to the optical image. In this case, the light in the second wavelength region output from the UC layer is confined between the first optical confinement layer and the second optical confinement layer and is subjected to diffraction based on the resonant mode forming layer. In the resonant mode forming layer, the centroids of the multiple different refractive index regions have a rotation angle set according to each different refractive index region around the lattice point of the imaginary square lattice. In this case, compared to the case where the centroids of multiple different refractive index regions are located at lattice points of a square lattice, the intensity of light output in the thickness direction of the resonant mode forming layer (in other words, the direction perpendicular to the light output surface of the optical device), i.e., the 0th order light, decreases, while the intensity of higher order light output in directions tilted relative to this direction, such as the +1st and -1st order lights, increases. Furthermore, the rotation angle around the lattice points of the centroids of each different refractive index region is individually set according to the optical image, thereby enabling independent modulation of the light phase for each different refractive index region and outputting an optical image of arbitrary shape in the second wavelength region.

[0085] (5) The optical device can also be an optical device that outputs an optical image (e.g., a phase-modulated light-emitting element). As an embodiment of the invention, in an imaginary square lattice set on a reference plane to which multiple different refractive index regions are to be formed, the centroid of each of the multiple different refractive index regions is located on a straight line passing through the corresponding lattice point of the imaginary square lattice and inclined relative to the square lattice, and the distance between the centroid and the corresponding lattice point is individually set according to the optical image. Light in the second wavelength region output from the UC layer is confined between the first and second light confinement layers and subjected to diffraction based on the resonant mode forming layer. In the resonant mode forming layer, the centroids of the multiple different refractive index regions are arranged on a straight line passing through the lattice point of the imaginary square lattice and inclined relative to the square lattice. In this case, the light intensity of the light output in the direction perpendicular to the light output surface (0th order light) decreases, while the light intensity of higher order light, such as +1st and -1st order light, output in the direction inclined relative to this direction increases. Furthermore, the distance between the centroid of each region of different refractive index and the corresponding lattice point is individually set according to the optical image, thereby enabling the phase of light to be modulated independently for each region of different refractive index and outputting an optical image of arbitrary shape for the second wavelength region.

[0086] (6) As one aspect of the present invention, it may also include a diffractive optical element (DOE) disposed on the opposite side of the UC layer relative to the second light confinement layer (i.e., the second light confinement layer is located between the diffractive optical element and the UC layer). In this case, by pre-forming a phase distribution based on an optical image of arbitrary shape in the diffractive optical element, the laser light in the second wavelength region that has passed through the second light confinement layer (output) can be converted into an optical image of arbitrary shape. Therefore, an optical image of arbitrary shape in the second wavelength region can be output.

[0087] (7) As one aspect of the invention, it may also include a spatial light modulator disposed on the opposite side of the UC layer relative to the second light confinement layer (i.e., the second light confinement layer is located between the spatial light modulator and the UC layer). In this case, by presenting a phase pattern based on an optical image of arbitrary shape in the spatial light modulator, the laser light in the second wavelength region output through the second light confinement layer can be converted into an optical image of arbitrary shape. Therefore, an optical image of arbitrary shape in the second wavelength region can be output.

[0088] (8) As one aspect of the present invention, it may also include a dichroic mirror disposed on the opposite side of the UC layer relative to the second light-confining layer (i.e., the second light-confining layer is located between the dichroic mirror and the UC layer). The dichroic mirror has a light transmittance in the second wavelength region that is greater than that in the first wavelength region. In this case, even if a portion of the excitation light passes through the second light-confining layer without being absorbed by the UC layer and mixes with the light in the second wavelength region, the excitation light component in the light after passing through the dichroic mirror is reduced because the excitation light is less likely to pass through the dichroic mirror than the light in the second wavelength region. Therefore, it is possible to suppress the mixing of excitation light with the light in the second wavelength region output from the optical device.

[0089] (9) As an embodiment of the present invention, the first wavelength region may be the near-infrared region and the second wavelength region may be the visible region. As mentioned above, light in the near-infrared region can be easily obtained by light-emitting devices, for example, those mainly comprising GaAs-based semiconductors. In contrast, light in the visible region, especially the green to blue regions, can be obtained by light-emitting devices, for example, those mainly comprising nitride semiconductors such as GaN, but due to the characteristics of the materials, it is difficult to obtain practical light output characteristics in photonic crystal surface-emitting lasers or phase-modulated light-emitting elements. In this regard, the optical device according to the present invention does not require the use of nitride semiconductors such as GaN in the resonant mode forming layer, and the material selection of the resonant mode forming layer is highly flexible. Therefore, it is possible to provide practical photonic crystal surface-emitting lasers and phase-modulated light-emitting elements capable of outputting light in the visible region. As a result, rich color display in the visible region is possible.

[0090] (10) Furthermore, the light-emitting device of the present invention, as one embodiment, includes: an optical device comprising the structure described above; and an excitation source integrated with the optical device via a first light confinement layer. Through this structure, excitation light output from the excitation source can be supplied to the UC layer. According to this light-emitting device, a practical surface-emitting self-emissive device capable of emitting light in a relatively short wavelength region, such as the visible region, can be provided.

[0091] (11) As an embodiment of the present invention, the excitation source may also include a photonic crystal surface-emitting laser disposed on the opposite side of the UC layer relative to the first optical confinement layer (i.e., the first optical confinement layer is disposed between the UC layer and the photonic crystal surface-emitting laser). Furthermore, it is preferable that the light transmittance in the first wavelength region of the first optical confinement layer is greater than the light transmittance in the second wavelength region of the first optical confinement layer. In this case, the excitation light output from the photonic crystal surface-emitting laser is supplied to the UC layer after passing through the first optical confinement layer. Therefore, light in the second wavelength region can be appropriately output from the optical device. Furthermore, according to this light-emitting device, the optical device is formed on the light output surface of the photonic crystal surface-emitting laser with the same stacking direction, thus it is easy to manufacture a light-emitting device that integrates the optical device and the excitation source.

[0092] (12) As one aspect of the present invention, in a photonic crystal surface-emitting laser or a phase-modulated light-emitting element, a PC layer larger than the light-emitting region is provided to suppress reflections at the region ends. In this case, in the aforementioned light-emitting device, the area of ​​the PC layer of the photonic crystal surface-emitting laser, viewed from the stacking direction of the photonic crystal surface-emitting laser, is larger than the area of ​​the UC layer, viewed from the stacking direction of the optical device. Furthermore, in this case, as one aspect of the present invention, the photonic crystal surface-emitting laser includes a semiconductor substrate, a semiconductor laminate, a first electrode, and a second electrode. The semiconductor substrate has a main surface and a back surface. The semiconductor laminate is disposed on the main surface of the semiconductor substrate and includes an active layer and a PC layer. The first electrode is made of a metallic material and is disposed on the back surface of the semiconductor substrate. The second electrode is disposed on the semiconductor laminate. Thus, the first electrode may also have an opening for allowing excitation light to pass through, and at least a portion of the first light-confining layer is disposed within the opening of the first electrode. By making the first electrode disposed on the back side of the semiconductor substrate metallic, a larger current can be supplied compared to a transparent electrode, thereby improving the luminous intensity of the photonic crystal surface-emitting laser. Furthermore, by disposing at least a portion of the first light-confining layer within the opening of the first electrode, the first light-confining layer and the back side of the semiconductor substrate can be brought close together. Additionally, in the light-emitting device of the present invention, the active layer, the PC layer, and the phase modulation layer can all be sandwiched between capping layers with lower refractive indices. This effectively confines light to the active layer and the PC layer.

[0093] (13) As one aspect of the present invention, the excitation source may also include a plurality of photonic crystal surface-emitting lasers disposed on the opposite side of the UC layer relative to the first optical confinement layer (i.e., the first optical confinement layer is disposed between the UC layer and the plurality of photonic crystal surface-emitting lasers). Furthermore, the plurality of photonic crystal surface-emitting lasers are arranged in a one-dimensional or two-dimensional configuration along the surface of the first optical confinement layer. The light transmittance in the first wavelength region of the first optical confinement layer is greater than the light transmittance in the second wavelength region of the first optical confinement layer. In this case, the excitation light output from the plurality of photonic crystal surface-emitting lasers is supplied to the UC layer through the first optical confinement layer, thus enabling the appropriate output of light in the second wavelength region from the optical device. Furthermore, according to this light-emitting device, since the excitation light is generated using a plurality of photonic crystal surface-emitting lasers arranged in a one-dimensional or two-dimensional configuration, the area of ​​the optical device viewed from the light output direction can be made larger. Therefore, for example, the area of ​​the optical image output from the light-emitting device can be made larger.

[0094] (14) As an embodiment of the present invention, a structure comprising multiple photonic crystal surface-emitting lasers may be provided, each photonic crystal surface-emitting laser including a semiconductor substrate, a semiconductor laminate, a first electrode, and a second electrode. The semiconductor substrate has a main surface and a back surface. The semiconductor laminate is disposed on the main surface of the semiconductor substrate and includes an active layer and a PC. The first electrode is disposed on the back surface of the semiconductor substrate and is composed of a transparent conductive film. The second electrode is disposed on the semiconductor laminate. Furthermore, the excitation light passes through the first electrode and reaches the first light confinement layer. In this case, compared to the case where the first electrode is a metal electrode with an opening, the current density distribution supplied to the active layer of the photonic crystal surface-emitting laser can be made nearly uniform. Therefore, the light intensity distribution in the plane perpendicular to the output direction of the excitation light can be made nearly uniform, and the excitation uniformity of the UC layer can be improved.

[0095] (15) As one aspect of the present invention, the area of ​​the PC layer of the photonic crystal surface-emitting laser, viewed from the stacking direction of the photonic crystal surface-emitting laser, can also be smaller than the area of ​​the UC layer, viewed from the stacking direction of the optical device. Furthermore, in this case, as one aspect of the present invention, the photonic crystal surface-emitting laser includes a semiconductor substrate, a semiconductor laminate, a first electrode, and a second electrode. The semiconductor substrate has a main surface and a back surface. The semiconductor laminate is disposed on the main surface of the semiconductor substrate and includes an active layer and a PC layer. The first electrode is disposed on an area of ​​the main surface of the semiconductor substrate that is exposed and not covered by the semiconductor laminate. The second electrode is disposed on the semiconductor laminate. In this structure, the first light-confining layer is disposed on the back surface of the semiconductor substrate. Thus, since both the first electrode and the second electrode are disposed on the main surface side of the semiconductor substrate, mounting the light-emitting device of the present invention to the substrate becomes easier. Furthermore, as an embodiment of the present invention, the excitation source may also include a plurality of photonic crystal surface-emitting lasers disposed on the opposite side of the UC layer relative to the first optical confinement layer (i.e., the first optical confinement layer is disposed between the UC layer and the plurality of photonic crystal surface-emitting lasers). Moreover, the plurality of photonic crystal surface-emitting lasers are arranged in a one-dimensional or two-dimensional configuration along the surface of the first optical confinement layer. The light transmittance in the first wavelength region of the first optical confinement layer is greater than the light transmittance in the second wavelength region of the first optical confinement layer.

[0096] The methods listed above in the "[Description of Embodiments of the Invention]" section can be applied to each of the remaining methods, or to all combinations of the remaining methods.

[0097] [Details of embodiments of the present invention]

[0098] Hereinafter, with reference to the accompanying drawings, the specific structures of the optical and light-emitting devices of the present invention will be described in detail. Furthermore, the present invention is not limited to these illustrations and is intended to include all modifications within the meaning and scope of the claims and their equivalents. In addition, in the description of the drawings, the same reference numerals are used for the same elements, and repeated descriptions are omitted.

[0099] (First Embodiment)

[0100] Figure 1This is a cross-sectional view showing the structure of the light-emitting device 1A according to the first embodiment of the present invention. The light-emitting device 1A includes an optical device 10A and an excitation light source 20A. The excitation light source 20A generates excitation light encompassed in a first wavelength region. The first wavelength region is, for example, the near-infrared region (0.75 μm to 1.4 μm). In one example, the wavelength of the excitation light is 940 nm. The optical device 10A and the excitation light source 20A of the first embodiment are both photonic crystal surface emitting lasers (PCSELs). The optical device 10A receives excitation light from the excitation light source 20A and outputs light Lout in a second wavelength region shorter than the first wavelength region. The second wavelength region is encompassed in the visible light region, for example, the red region (620 nm to 750 nm), the green region (495 nm to 570 nm), or the blue region (450 nm to 495 nm). Hereinafter, the optical device 10A and the excitation light source 20A will be described in detail. Furthermore, for ease of understanding, an XYZ Cartesian coordinate system is defined in the diagram as needed. The light-emitting device 1A forms a standing wave along a specified direction (in-plane direction) on a reference plane parallel to the XY plane, causing the light source Lout to be output in a direction perpendicular to the light output surface (Z direction).

[0101] The optical device 10A of the first embodiment includes a UC layer 11 (upconversion layer), a PC layer 12A (photonic crystal layer), a first light-reflecting layer 13 serving as a first light confinement layer, and a second light-reflecting layer 14 serving as a second light confinement layer. These layers are parallel to the XY plane and are stacked along the Z direction (consistent with the thickness direction of each layer). Light Lout passes through the second light-reflecting layer 14 (output from the second light-reflecting layer 14). Details regarding the upconversion material are described, for example, in the aforementioned Non-Patent Document 1.

[0102] According to the aforementioned Non-Patent Document 1, the UC layer 11 is a layer containing an upconversion material. The UC layer 11 may consist solely of the upconversion material, or the upconversion material may be dispersed within the resin. The upconversion material is a material that receives excitation light contained in a first wavelength region and outputs light in a second wavelength region. Unlike the usual phenomenon of light emission where high-energy (short-wavelength) photons are excited to produce low-energy (long-wavelength) photons, upconversion is the phenomenon of high-energy (short-wavelength) photons being excited by low-energy (long-wavelength) photons. Furthermore, as phenomena of generating shorter-wavelength light from a certain wavelength of light, there are light emission based on two-photon absorption and second harmonic generation, but upconversion differs from these phenomena.

[0103] In upconversion, there exists: based on lanthanide ions (Er 3+ Ho 3+ Tm 3+Upconversion occurs through lanthanides and is based on so-called triplet-triplet annihilation (TTA). According to the aforementioned non-patent literature 1, almost all known upconversion materials contain lanthanide ions as sensitizers and luminescent agents. This is because lanthanide ions have large f-electrons with long lifetimes (~ms). The mechanisms of lanthanide upconversion are classified into three main processes: absorption of excited states, energy-shifting upconversion, and photon avalanche.

[0104] Among these, the main raw material (upconversion material) of the resin (UV-curable resin) applicable to UC layer 11, preferably selected from at least one of acrylates and methacrylates, is the photopolymerizable monomer. Furthermore, the selected photopolymerizable monomer can be either a monofunctional monomer or a polyfunctional monomer. Examples of monofunctional monomers include carboxyethyl acrylate, isosorbide acrylate, octyl acrylate, lauryl acrylate, stearyl acrylate, nonylphenoxy polyethylene glycol acrylate, dicyclopentenyl acrylate, dicyclopentenoxyethyl acrylate, dicyclopentyl acrylate, benzyl acrylate, phenoxyethyl acrylate, dicyclopentenoxyethyl methacrylate, dicyclopentyl methacrylate, benzyl methacrylate, octyl methacrylate, and 2-ethylhexyl-diethylene glycol acrylate. Examples of multifunctional monomers include diethylene glycol acrylate, 1,4-butanediol diacrylate, 1,6-hexanediol acrylate, 1,9-nonanediol diacrylate, polypropylene glycol diacrylate, EO-modified bisphenol A diacrylate, dicyclopentyl acrylate diacrylate, neopentyl glycol-modified trimethylolpropane diacrylate, 4,4'-disacryloyloxystilbene, diethylene glycol methacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol methacrylate, 1,9-nonanediol dimethacrylate, dicyclopentyl dimethacrylate, neopentyl glycol dimethacrylate, EO-modified bisphenol A dimethacrylate, tris(2-acryloyloxyethyl) isocyanurate, and caprolactone-modified dipentaerythritol hexaacrylate.

[0105] PC layer 12A, serving as a diffraction lattice layer, functions as a resonant mode forming layer in the first embodiment. PC layer 12A is disposed between the first light-reflecting layer 13 or the second light-reflecting layer 14 and the UC layer 11 (in the example shown, it is disposed between the first light-reflecting layer 13 and the UC layer 11). In the example shown, PC layer 12A is adjacent to the UC layer 11.

[0106] PC layer 12A includes a base layer 12a and multiple regions 12b with different refractive indices. The base layer 12a is composed of a first refractive index medium. The multiple regions 12b with different refractive indices are composed of a second refractive index medium having a refractive index different from that of the first refractive index medium, and are located within the base layer 12a. The base layer 12a can be composed of, for example, an inorganic material such as SiO2, or an organic material such as resin. The constituent material of the base layer 12a can be insulating, semiconductor, or conductive. The regions 12b with different refractive indices can be vacancies or structures in which a solid medium is embedded within the vacancies. When the regions 12b with different refractive indices are vacancies, PC layer 12A may also have a layer on the base layer 12a for covering the vacancies. The constituent material of this layer can be the same as or different from that of the base layer 12a.

[0107] Multiple regions 12b with different refractive indices are arranged in a two-dimensional and periodic manner in a plane perpendicular to the thickness direction (Z direction) of the PC layer 12A (a plane parallel to the XY plane). With an effective refractive index (equivalent refractive index) of n1, the wavelength λ1 selected by the PC layer 12A (=a1×n1, where a1 is the lattice spacing) is included within the emission wavelength range of the UC layer 11 (the second wavelength region). The PC layer 12A forms a resonant mode of light with wavelength λ1 on a plane perpendicular to its thickness direction. The arrangement period of the multiple regions 12b with different refractive indices is set such that light with wavelength λ1 oscillates at the Γ point or M point. Therefore, the PC layer 12A can select wavelength λ1 from the emission wavelength of the UC layer 11 and output it externally.

[0108] Figure 2 This is a top view of PC layer 12A. Here, in PC layer 12A, an imaginary square lattice is set on a plane (reference plane) parallel to the XY plane. One side of the square lattice is parallel to the X-axis, and the other side is parallel to the Y-axis. At this time, a square unit constitutive region R centered on the lattice point O of the square lattice can be set in a two-dimensional shape, covering multiple columns (x = 0, 1, 2, 3) along the X-axis and multiple rows (y = 0, 1, 2) along the Y-axis. The unit constitutive region R is a region enclosed by straight lines that bisect the lattice points of the imaginary square lattice. Multiple regions 12b with different refractive indices are set in a determined number of one or more within each unit constitutive region R. The planar shape of the different refractive index regions 12b is, for example, circular. Within the unit constitutive region R(x, y), the centroid G of the different refractive index regions 12b overlaps (aligns) with the lattice point O(x, y). The periodic structure of multiple refractive index regions 12b is not limited to this; for example, a triangular lattice can be set instead of a square lattice.

[0109] Figure 2This example illustrates that the shapes of the different refractive index regions 12b on the reference plane are circular, but these regions can also have shapes other than circular. For example, the shapes of the different refractive index regions 12b can also exhibit mirror symmetry (linear symmetry). Here, mirror symmetry (linear symmetry) means that, separated by a straight line on a reference plane parallel to the XY plane, the planar shapes of the different refractive index regions 12b on one side of that line and the planar shapes of the different refractive index regions 12b on the other side of that line can be mirror symmetric (linear symmetric). An example of a shape with mirror symmetry (linear symmetry) is, for example... Figure 3 (a) shows a perfect circle. Figure 3 (b) shows a square. Figure 3 (c) shows a regular hexagon. Figure 3 (d) shows a regular octagon. Figure 3 (e) shows a regular 16-sided polygon. Figure 3 (f) shows a rectangle. Figure 3 (g) shows an ellipse.

[0110] The shape of the different refractive index regions 12b defined on a reference plane parallel to the XY plane can also be a shape that does not have 180° rotational symmetry. As an example of such a shape, for example... Figure 4 (a) shows an equilateral triangle. Figure 4 (b) shows an isosceles right triangle. Figure 4 (c) shows the shape of two circles or a portion of an ellipse overlapping. Figure 4 (d) shows an oval shape (a shape deformed in such a way that the dimension along the minor axis near one end of the major axis of the ellipse is smaller than the dimension along the minor axis near the other end). Figure 4 (e) shows a teardrop shape (a shape in which one end along the major axis of an ellipse is deformed into a pointed end that protrudes along the major axis). Figure 4 (f) shows an isosceles triangle. Figure 4 (g) shows an arrow-shaped rectangle (one side of which is concave in a triangular shape, and the opposite side is a tapered triangular shape). Figure 4 (h) shows a trapezoid. Figure 4 (i) shows a pentagon, Figure 4 (j) shows the shape of two rectangles partially overlapping each other. Figure 4 (k) shows a shape in which parts of two rectangles overlap each other and do not have mirror symmetry. In this way, by using the shape of different refractive index regions 12b, which does not have 180° rotational symmetry, higher light output can be obtained.

[0111] Figure 5 (a)~ Figure 5(k) is a top view showing another example of the shape of different refractive index regions defined on a reference plane parallel to the XY plane. In this example, multiple different refractive index regions 12c, different from the multiple different refractive index regions 12b, are also provided. Each different refractive index region 12c is composed of a second refractive index medium with a refractive index different from the first refractive index medium of the base layer 12a. The different refractive index regions 12c and 12b can similarly be vacancies or formed by embedding a solid medium in the vacancies. The different refractive index regions 12c and 12b are provided in a one-to-one correspondence. Thus, the centroid G of the combined different refractive index regions 12b and 12c is located at a lattice point of the unit constitutive region R of the imaginary cubic lattice. Each different refractive index region 12b or 12c is contained within the unit constitutive region R of the imaginary cubic lattice.

[0112] The planar shape of region 12c with different refractive indices is, for example, circular, but like region 12b with different refractive indices, it can have various shapes. Figure 5 (a)~ Figure 5 (k) represents an example of the shape and relative relationship of different refractive index regions 12b and 12c in the XY plane. Figure 5 (a) and Figure 5 (b) A way of representing the same shape in regions 12b and 12c with different refractive indices. Figure 5 (c) and Figure 5 (d) represents the pattern with the same shape in different refractive index regions 12b and 12c, in a way that a part of each other overlaps. Figure 5 (e) represents a pattern in which regions 12b and 12c with different refractive indices have the same shape, and regions 12b and 12c with different refractive indices are rotated relative to each other. Figure 5 (f) represents a graphical representation of regions 12b and 12c with different shapes. Figure 5 (g) represents a graphic showing that the different refractive index regions 12b and 12c have different shapes from each other, and that the different refractive index regions 12b and 12c are rotated relative to each other.

[0113] In addition, it can also be like Figure 5 (h)~ Figure 5 As shown in (k), the different refractive index regions 12b are configured as two regions 12b1 and 12b2 separated from each other. Therefore, the distance between the centroid of regions 12b1 and 12b2 combined (equivalent to the centroid of a single different refractive index region 12b) and the centroid of the different refractive index region 12c can be arbitrarily set within the unit constitutive region R. Furthermore, in this case, it is also possible to... Figure 5As shown in (h), regions 12b1, 12b2, and regions 12c with different refractive indices have the same shape. Alternatively, they can be as follows: Figure 5 As shown in (i), two patterns in regions 12b1, 12b2, and the region 12c with different refractive indices differ from the other patterns. Furthermore, it is also possible to... Figure 5 As shown in (j), besides the angle of the straight line connecting regions 12b1 and 12b2 relative to the X-axis, the angles of different refractive index regions 12c relative to the X-axis can also be arbitrarily set within the unit constitutive region R. Furthermore, it can also be as follows... Figure 5 As shown in (k), while regions 12b1, 12b2 and regions 12c with different refractive indices maintain the same relative angle to each other, the angle of the straight line connecting regions 12b1 and 12b2 relative to the X-axis is arbitrarily set within the unit constitutive region R.

[0114] In this configuration, multiple regions 12b with different refractive indices can be arranged for each unit constituting region R. Here, a unit constituting region R is defined as the region with the smallest area, enclosed by perpendicular bisecting lines between the lattice points of a given unit constituting region R and the lattice points of other periodically arranged unit constituting regions, corresponding to the Wigner-Seitz cell in solid-state physics. Alternatively, multiple regions 12b with different refractive indices within a single unit constituting region R can have identical shapes, separated by their centroids. Furthermore, the shapes of the different refractive index regions 12b can be identical within the unit constituting region R, and can be overlapped between them through translation operations, or through a combination of translation and rotation operations. In this case, fluctuations in the photonic band structure are reduced, resulting in a narrower linewidth spectrum. Alternatively, the shapes of the different refractive index regions may not necessarily be identical within the unit constituting region R, and their shapes may differ between adjacent unit constituting regions R.

[0115] In the above structure, the regions 12b with different refractive indices are vacancies. However, the regions 12b with different refractive indices can also be formed by embedding inorganic materials with refractive indices different from those of the base layer 12a within the vacancies. In this case, for example, inorganic materials can be embedded within the vacancies of the base layer 12a after etching. Alternatively, after forming regions 12b with different refractive indices by embedding inorganic materials within the vacancies of the base layer 12a, the same inorganic materials as the regions 12b with different refractive indices can be deposited on top of them. When the regions 12b with different refractive indices are vacancies, inert gases such as argon and nitrogen, or gases such as hydrogen and air, can also be sealed into these vacancies.

[0116] Refer again Figure 1The first light-reflecting layer 13 has light-reflecting properties that reflect at least a portion of light in the second wavelength region containing the emission wavelength of the UC layer 11. The first light-reflecting layer 13 is located on the excitation source 20A side relative to the UC layer 11 and the PC layer 12A. The first light-reflecting layer 13 is, for example, made of a dielectric multilayer film (multilayer stacked structure). The first light-reflecting layer 13 of the first embodiment is a dichroic mirror that reflects light in the second wavelength region containing the emission wavelength of the UC layer 11 and allows light in the first wavelength region containing the wavelength of the excitation light output from the excitation source 20A to pass through. In the example shown, the first light-reflecting layer 13 is adjacent to the PC layer 12A. However, not limited to the example shown, other layers or gaps may be provided between the first light-reflecting layer 13 and the PC layer 12A (or, if the UC layer 11 is located between the first light-reflecting layer 13 and the PC layer 12A, other layers or gaps may be provided between the first light-reflecting layer 13 and the UC layer 11).

[0117] The second light-reflecting layer 14 has the light-reflecting characteristic of reflecting a portion of the light emitted by the UC layer 11 (the second wavelength region) while allowing the remainder to pass through. The second light-reflecting layer 14 is located on the opposite side of the excitation light source 20A relative to the UC layer 11 and the PC layer 12A, with the UC layer 11 and PC layer 12A sandwiched between it and the first light-reflecting layer 13. The second light-reflecting layer 14 is, for example, composed of a dielectric multilayer film (multilayer stacked structure). Figure 1 In this example, the second light-reflecting layer 14 is adjacent to the UC layer 11. This is not limited to... Figure 1 Alternatively, other layers or gaps may be provided between the second light-reflecting layer 14 and the UC layer 11 (or, in the case where the PC layer 12A is located between the UC layer 11 and the second light-reflecting layer 14, other layers or gaps may be provided between the second light-reflecting layer 14 and the PC layer 12A).

[0118] The light-emitting device 1A according to the first embodiment further includes a substrate 15 and a dichroic mirror 16. The substrate 15 is formed of a material, such as a quartz plate, that allows light of the emission wavelength (second wavelength region) of the UC layer 11 to pass through. A second light-reflecting layer 14 is formed on one side of the substrate 15, and a dichroic mirror 16 is formed on the other side. The dichroic mirror 16 is disposed on the opposite side of the UC layer 11 relative to the second light-reflecting layer 14. The dichroic mirror 16 reflects light of the first wavelength region containing the wavelength of the excitation light, and allows light of the second wavelength region containing the emission wavelength of the UC layer 11 to pass through. In other words, the light transmittance in the second wavelength region of the dichroic mirror 16 is greater than the light transmittance in the first wavelength region. The dichroic mirror 16 is, for example, made of a dielectric multilayer film.

[0119] The dielectric multilayer film constituting the first light-reflecting layer 13, the second light-reflecting layer 14, and the dichroic mirror 16 is formed by alternately stacking a first layer having a first refractive index and a second layer having a second refractive index different from the first refractive index. The wavelength-light reflection (or transmission) characteristics of the dielectric multilayer film are determined based on the refractive index difference between the first and second refractive indices, the thicknesses of the first and second layers, and the number of layers stacked. Materials constituting the first and second layers, such as titanium oxide (TiO2), silicon dioxide (SiO2), silicon monoxide (SiO), niobium oxide (Nb2O5), tantalum pentoxide (Ta2O5), magnesium fluoride (MgF2), titanium oxide (TiO2), aluminum oxide (Al2O3), cerium oxide (CeO2), indium oxide (In2O3), and zirconium oxide (ZrO2), can be used.

[0120] The thickness of UC layer 11 is, for example, 0.1 μm to 50 μm. The thickness of PC layer 12A is, for example, 70 nm. The thickness of the first light-reflecting layer 13 is, for example, 10 μm. The thickness of the second light-reflecting layer 14 is, for example, 10 μm.

[0121] Next, the excitation light source 20A of the first embodiment will be described. The excitation light source 20A is integrated with the optical device 10A via the first light-reflecting layer 13 and supplies excitation light to the UC layer 11. As described above, the excitation light source 20A of the first embodiment is a PCSEL and is disposed at a position where the first light-reflecting layer 13 is sandwiched between it and the UC layer 11.

[0122] The excitation light source 20A includes: a semiconductor substrate 21 having a main surface 21a and a back surface 21b; a semiconductor stack disposed on the main surface 21a of the semiconductor substrate 21; a first electrode 27 (n-electrode) and a second electrode 28 (p-electrode). The semiconductor stack includes an active layer 22, a PC layer 23 (photonic crystal layer), a first capping layer 24, a second capping layer 25, and a contact layer 26. The first capping layer 24 is disposed on the main surface 21a of the semiconductor substrate 21, and in one example, is in contact with the main surface 21a of the semiconductor substrate 21. The second capping layer 25 is disposed on the first capping layer 24. The active layer 22 is disposed between the first capping layer 24 and the second capping layer 25. The band gap of the first capping layer 24 and the band gap of the second capping layer 25 are wider than the band gap of the active layer 22. The PC layer 23 is disposed between the first capping layer 24 and the active layer 22, or between the active layer 22 and the second capping layer 25. Figure 1 In this example, the PC layer 23 is disposed between the active layer 22 and the second capping layer 25, and is in contact with both the second capping layer 25 and the active layer 22. The contact layer 26 is disposed on the second capping layer 25. The thickness directions of the semiconductor substrate 21, the active layer 22, the PC layer 23, the first capping layer 24, the second capping layer 25, and the contact layer 26 are aligned with the Z-direction.

[0123] Alternatively, a light guiding layer for adjusting light distribution can be disposed between at least one of the first capping layer 24 and the active layer 22, and between the active layer 22 and the second capping layer 25, as needed. The light guiding layer may also include a carrier barrier layer for effectively confining carriers within the active layer 22. When the light guiding layer is disposed between the active layer 22 and the second capping layer 25, the PC layer 23 is disposed between the second capping layer 25 and the light guiding layer.

[0124] The PC layer 23 (diffraction lattice layer) is configured to include a base layer 23a and multiple regions 23b with different refractive indices. The base layer 23a is a semiconductor layer composed of a third refractive index medium. The multiple regions 23b with different refractive indices are composed of a fourth refractive index medium with a refractive index different from that of the third refractive index medium and are located within the base layer 23a. The multiple regions 23b with different refractive indices are arranged in a two-dimensional and periodic manner on a reference plane (a plane parallel to the XY plane) perpendicular to the thickness direction of the PC layer 23. With the effective refractive index (equivalent refractive index) set to n2, the wavelength λ2 (=a2×n2, where a2 is the lattice spacing) selected by the PC layer 23 is included in the emission wavelength range of the active layer 22 (the first wavelength region). The arrangement period of the multiple regions 23b with different refractive indices is set so that light of wavelength λ2 oscillates at the Γ point. Therefore, the PC layer 23 can perform diffraction in the Z direction by selecting wavelength λ2 in the emission wavelength of the active layer 22. The arrangement (except for the arrangement period) and shape variation of the multiple regions 23b with different refractive indices are the same as those of the PC layer 12A mentioned above (see reference). Figure 2 , Figure 3 (a)~ Figure 3 (g) Figure 4 (a)~ Figure 4 (k) and Figure 5 (a)~ Figure 5 (k)).

[0125] The first electrode 27 is a metal electrode disposed on the back surface 21b of the semiconductor substrate 21. The first electrode 27 is in ohmic contact with the semiconductor substrate 21. When viewed along a direction perpendicular to the back surface 21b of the semiconductor substrate 21, the first electrode 27 has a rectangular frame shape with an opening 27a for allowing excitation light to pass through. The back surface 21b of the semiconductor substrate 21 is exposed from the first electrode 27 through the opening 27a, and the exposed portion is opposite to the first light-reflecting layer 13 of the optical device 10A. In one example, at least a portion of the first light-reflecting layer 13 in the thickness direction is disposed within the opening 27a and is in contact with the back surface 21b of the semiconductor substrate 21.

[0126] The planar shape and dimensions of the first light-reflecting layer 13 are consistent with those of the UC layer 11. On the other hand, the planar shape and dimensions of the outer edge of the first electrode 27 are consistent with those of the PC layer 23. Therefore, the area of ​​the PC layer 23, viewed along the stacking direction (Z direction) of the excitation light source 20A, is at least as large as the area of ​​the UC layer 11, viewed from the stacking direction (Z direction) of the optical device 10A, by the amount of the first electrode 27. In other words, when viewed from the Z direction, the outline of the UC layer 11 is located inside the outline of the PC layer 23.

[0127] The second electrode 28 is on the semiconductor laminate (in Figure 1 In this example, at least one metal electrode is disposed on the contact layer 26 in the region (central region of the semiconductor stack) that projects the opening 27a of the first electrode 27. The second electrode 28 is in ohmic contact with the contact layer 26. The portion of the contact layer 26 that is not in contact with the second electrode 28 may also be removed. The second electrode 28 also has the function of reflecting light generated in the active layer 22.

[0128] As an example, the semiconductor substrate 21 is a GaAs substrate, and the first capping layer 24, active layer 22, PC layer 23, second capping layer 25, and contact layer 26 are made of GaAs-based semiconductors. Furthermore, the first capping layer 24 is an AlGaAs layer. The active layer 22 has a multi-quantum-well structure (barrier layer: AlGaAs / quantum well layer: InGaAs, the number of well layers is, for example, 3). The basic layer 23a of the PC layer 23 is an AlGaAs layer or a GaAs layer, and the regions 23b with different refractive indices are vacancies. The second capping layer 25 is an AlGaAs layer. The contact layer 26 is a GaAs layer. In this case, the thickness of the semiconductor substrate 21 is, for example, 150 μm. The thickness of the first capping layer 24 is, for example, 2000 nm. The thickness of the active layer 22 is, for example, 140 nm. The thickness of the PC layer 23 is, for example, 300 nm. The thickness of the second capping layer 25 is, for example, 2000 nm. The thickness of the contact layer 26 is, for example, 200 nm. Assuming the emission wavelength is 980nm, the refractive index of the first capping layer 24 is, for example, about 3.11, the refractive index of the active layer 22 is, for example, about 3.49, the refractive index of the second capping layer 25 is, for example, about 3.27, and thus the refractive index of the contact layer 26 is, for example, about 3.52.

[0129] The first capping layer 24 is given the same conductivity type as the semiconductor substrate 21, while the second capping layer 25 and contact layer 26 are given the opposite conductivity type to the semiconductor substrate 21. In one example, the semiconductor substrate 21 and the first capping layer 24 are n-type, and the second capping layer 25 and contact layer 26 are p-type. When the PC layer 23 is disposed between the active layer 22 and the first capping layer 24, the PC layer 23 has the same conductivity type as the semiconductor substrate 21. Conversely, when the PC layer 23 is disposed between the active layer 22 and the second capping layer 25, the PC layer 23 has the opposite conductivity type to the semiconductor substrate 21. The impurity concentration is, for example, 1 × 10⁻⁶. 16 ~1×10 21 / cm 3 In the absence of any intentionally added impurities, the intrinsic (type i) impurity concentration is 1 × 10⁻⁶. 16 / cm 3 The active layer 22 is not limited to intrinsic (type i) and may also be doped. Regarding the impurity concentration of the PC layer 23, it may also be set to intrinsic (type i) when it is necessary to suppress the effects of light absorption through impurity energy levels.

[0130] The material of the first electrode 27 is appropriately selected based on the constituent material of the semiconductor substrate 21. In the case where the semiconductor substrate 21 is an n-type GaAs substrate, the first electrode 27 may, for example, contain a mixture of Au and Ge. In one example, the first electrode 27 has a single AuGe layer or a stacked structure of AuGe layers and Au layers. The material of the second electrode 28 can be appropriately selected based on the constituent material of the contact layer 26. In the case where the contact layer 26 is made of p-type GaAs, the second electrode 28 may, for example, be made of a material containing at least one of Cr, Ti, and Pt and Au, for example, a stacked structure of Cr and Au layers. However, the materials of the first electrode 27 and the second electrode 28 are not limited to these, as long as ohmic bonding can be achieved.

[0131] The light-emitting device 1A of the first embodiment having the above structure operates as follows. When a driving current is supplied between the first electrode 27 and the second electrode 28, electron-hole recombination occurs within the active layer 22, and light in a first wavelength region (e.g., the near-infrared region) is emitted from the active layer 22. The electrons and holes contributing to this light emission, as well as the generated light, are efficiently distributed between the first capping layer 24 and the second capping layer 25. Because the light emitted from the active layer 22 is distributed between the first capping layer 24 and the second capping layer 25, it enters the interior of the PC layer 23, forming a resonant mode in the direction along the main surface 21a of the semiconductor substrate 21, corresponding to the lattice structure inside the PC layer 23. Thus, the light oscillates at a wavelength corresponding to the arrangement period of the plurality of regions 23b with different refractive indices, generating laser light as excitation light. Excitation light diffracted from PC layer 23 in the Z direction travels in a direction perpendicular to the main surface 21a of semiconductor substrate 21 and is output directly from back surface 21b through opening 27a to optical device 10A, or after being reflected by the second electrode 28, it is output from back surface 21b through opening 27a to optical device 10A.

[0132] In the optical device 10A, when the UC layer 11 receives excitation light contained in the first wavelength region, light in a second wavelength region (e.g., a visible region such as a red, green, or blue region) shorter than the first wavelength region is generated in the UC layer 11. This light in the second wavelength region is confined between the first light-reflecting layer 13 and the second light-reflecting layer 14 and undergoes diffraction based on the PC layer 12A. In the PC layer 12A, a resonant mode is formed along a predetermined direction (in-plane direction) on a plane perpendicular to the thickness direction (Z direction) of the PC layer 12A, and the light oscillates at a wavelength corresponding to the arrangement period of multiple regions 12b with different refractive indices (generating a laser Lout). The laser Lout travels along the thickness direction of the PC layer 12A, passes through the second light-reflecting layer 14, and is output to the outside of the optical device 10A.

[0133] Thus, according to the optical device 10A of the first embodiment, it is possible to output laser light with relatively short wavelengths such as green light and blue light based on relatively long wavelength excitation light such as near-infrared light and red light. Furthermore, since the PC layer 12A does not require the use of nitride semiconductors such as GaN, the material selection for the PC layer 12A is highly flexible, making it easy to improve the light confinement factor of the PC layer 12A. Moreover, it is not necessary to use a high-cost GaN substrate. Therefore, according to the first embodiment, a practical and low-cost optical device 10A as a PCSEL can be provided, for example, capable of outputting light in a relatively short wavelength region such as the visible region.

[0134] The layer forming the resonant mode in the optical device 10A, as in the first embodiment, can also be a PC layer 12A with multiple regions 12b of different refractive indices arranged periodically. In this case, a practical PCSEL can be provided, for example, capable of outputting light in a relatively short wavelength region such as the visible region.

[0135] As in the first embodiment, the optical device 10A may also include a dichroic mirror 16 disposed on the opposite side of the UC layer 11 relative to the second light-reflecting layer 14, wherein the light transmittance in the second wavelength region is greater than that in the first wavelength region. In this case, even if a portion of the excitation light passes through the second light-reflecting layer 14 without being absorbed by the UC layer 11 and mixes with the light in the second wavelength region, this excitation light is less likely to pass through the dichroic mirror 16 compared to the light in the second wavelength region, thus reducing the excitation light component in the light Lout after passing through the dichroic mirror 16. Therefore, it is possible to effectively suppress the mixing of excitation light into the light Lout in the second wavelength region output from the optical device 10A.

[0136] As in the first embodiment, the first wavelength region can be the near-infrared region, and the second wavelength region can be the visible region. Near-infrared light can be easily obtained, for example, using a light-emitting element that primarily comprises GaAs-based semiconductors. In contrast, while light in the visible region, such as the green and blue regions, can be obtained using light-emitting elements that primarily comprise nitride semiconductors such as GaN, practical light output characteristics are difficult to achieve in a PCSEL due to the material properties. Therefore, in the optical device 10A according to the first embodiment, it is not necessary to use nitride semiconductors such as GaN in the PC layer 12A, and the material selection for the PC layer 12A is highly flexible, thus providing a practical PCSEL capable of outputting light in the visible region. This allows for richer color display in the visible region.

[0137] The light-emitting device 1A of the first embodiment includes an optical device 10A and an excitation light source 20A integrated with the optical device 10A, which supplies excitation light to the UC layer 11. According to this light-emitting device 1A, a practical surface-emitting self-emissive device that can output light in a relatively short wavelength region, such as the visible region, can be provided.

[0138] As in the first embodiment, the excitation light source 20A may include a PCSEL disposed at a position where the first light-reflecting layer 13 is sandwiched between the excitation light source 20A and the UC layer 11, wherein the light transmittance in the first wavelength region of the first light-reflecting layer 13 is greater than the light transmittance in the second wavelength region of the first light-reflecting layer 13. In this case, since the excitation light output from the excitation light source 20A is supplied to the UC layer 11 through the first light-reflecting layer 13, light Lout in the second wavelength region can be appropriately output from the optical device 10A. Furthermore, according to this light-emitting device 1A, since the optical device 10A is formed on the light output surface (back surface 21b of the semiconductor substrate 21) of the excitation light source 20A with the same stacking direction, it is easy to manufacture a light-emitting device 1A that integrates the optical device 10A and the excitation light source 20A.

[0139] As in the first embodiment, the area of ​​the PC layer 23 viewed from the stacking direction of the excitation light source 20A may be larger than the area of ​​the UC layer 11 viewed from the stacking direction of the optical device 10A. In the PCSEL, a photonic crystal larger than the light-emitting area may be provided to suppress reflections at the edge of the region. In this case, the area of ​​the PC layer 23 of the PCSEL viewed from the stacking direction of the PCSEL is larger than the area of ​​the UC layer 11 viewed from the stacking direction of the optical device 10A.

[0140] As in the first embodiment, the excitation source 20A, which serves as a photonic crystal surface-emitting laser, may include a semiconductor substrate 21, a semiconductor laminate, a first electrode 27 made of metal, and a second electrode 28. The semiconductor laminate includes an active layer 22 and a PC layer 23 disposed on the main surface 21a of the semiconductor substrate 21. The first electrode 27 is disposed on the back surface 21b of the semiconductor substrate 21. The second electrode 28 is disposed on the semiconductor laminate. Thus, the first electrode 27 has an opening 27a for allowing excitation light to pass through, and at least a portion of the first light-reflecting layer 13 in the thickness direction may also be disposed within the opening 27a of the first electrode 27. By making the first electrode 27 disposed on the back surface 21b of the semiconductor substrate 21 metallic, a larger current can be supplied compared to a transparent electrode, resulting in an increase in the luminous intensity of the excitation source 20A. Therefore, the output intensity of light from the second wavelength region of the UC layer 11 can be increased, and the laser oscillation in the optical device 10A can be performed more stably. Furthermore, by disposing at least a portion of the first light-reflecting layer 13 in the thickness direction within the opening 27a of the first electrode 27, the first light-reflecting layer 13 and the back surface 21b of the semiconductor substrate 21 can be brought close to each other.

[0141] Here, the manufacturing method of the light-emitting device 1A according to the first embodiment will be described. First, on the main surface 21a of the semiconductor substrate 21, a base layer 23a consisting of a first capping layer 24, an active layer 22, and a PC layer 23 is grown sequentially by, for example, metal-organic vapor deposition (MOCVD). Next, an electron beam resist is coated on the surface of the base layer 23a, and regions 23b with different refractive indices are patterned using an electron beam scanning method. For example, the pattern of the electron beam resist is transferred to the base layer 23a by inductively coupled plasma (ICP) etching to form the PC layer 23. After removing the electron beam resist, a second capping layer 25 and a contact layer 26 are grown sequentially on the PC layer 23 by, for example, MOCVD.

[0142] Next, to thin the semiconductor substrate 21, the back surface 21b of the semiconductor substrate 21 is polished, and then mirror polishing is performed on the back surface 21b. Then, a first electrode 27 with an opening 27a is formed on the back surface 21b by photolithography, vacuum evaporation, and lift-off. Furthermore, a second electrode 28 is formed on the surface of the contact layer 26 by photolithography, vacuum evaporation, and lift-off. Either the formation of the first electrode 27 or the formation of the second electrode 28 can be performed first.

[0143] Furthermore, for example, a dielectric multilayer film serving as the first light-reflecting layer 13 is formed on the back surface 21b within the opening 27a of the first electrode 27 using vacuum evaporation. Then, continuously with the formation of the first light-reflecting layer 13, a base layer 12a (e.g., a SiO2 film) of a PC layer 12A is formed on the first light-reflecting layer 13 using vacuum evaporation. An electron beam resist is coated on the surface of the base layer 12a, and different refractive index regions 12b are patterned using an electron beam scanning method. Then, for example, the pattern of the electron beam resist is transferred to the base layer 12a by inductively coupled plasma (ICP) etching (formation of the PC layer 12A).

[0144] Next, the first electrode 27 is exposed by photolithography and wet etching. Then, an upconversion material is coated on the PC layer 12A by methods such as spin coating or screen printing to form the UC layer 11. Afterward, the layers formed on the semiconductor substrate 21 are cut into a chip shape by dicing.

[0145] Next, a substrate 15 is prepared, and a dielectric multilayer film serving as a second light-reflecting layer 14 is formed on one side of the substrate 15, for example, by vacuum evaporation. Furthermore, a dielectric multilayer film serving as a dichroic mirror 16 is formed on the other side of the substrate 15, for example, by vacuum evaporation. The formation order of the second light-reflecting layer 14 and the dichroic mirror 16 can be performed either way. Then, the second light-reflecting layer 14 and the UC layer 11 are bonded. Alternatively, the substrate 15 is fixed to the UC layer 11 such that the second light-reflecting layer 14 is adjacent to the UC layer 11. After the above steps, the light-emitting device 1A of the first embodiment can be manufactured.

[0146] (Second Implementation)

[0147] In the first embodiment described above, an optical device 10A comprising a PC layer 12A with periodically arranged regions 12b of different refractive indices was described. However, the optical device of the present invention is not limited to a PC layer (photonic crystal layer) with periodically arranged regions of different refractive indices, and can have various resonant mode forming layers. In recent years, phase-modulated light-emitting elements that output arbitrary optical images by controlling the phase and intensity spectra of light output from multiple light-emitting points arranged in a two-dimensional pattern have been investigated. Such phase-modulated light-emitting elements are called S-iPM (Static-integrable Phase Modulating) lasers, which output optical images of arbitrary shapes in space. The resonant mode forming layer may also contain a structure for such an S-iPM laser.

[0148] Figure 6 This is a cross-sectional view showing the structure of the light-emitting device 1B according to the second embodiment. The light-emitting device 1B of the second embodiment includes an optical device 10B instead of the optical device 10A of the first embodiment. The structure of the excitation light source 20A included in the light-emitting device 1B is the same as in the first embodiment. The difference between the optical device 10B of the second embodiment and the optical device 10A of the first embodiment lies in the structure of the resonant mode forming layer. In this second embodiment, the optical device 10B has a phase modulation layer 12B as the resonant mode forming layer instead of the PC layer 12A of the above embodiment.

[0149] Figure 7This is a top view of the phase modulation layer 12B. The phase modulation layer 12B includes: a base layer 12a composed of a first refractive index medium; and different refractive index regions 12b composed of a second refractive index medium with a refractive index different from that of the first refractive index medium. Here, in the phase modulation layer 12B, an imaginary square lattice is set on a reference plane parallel to the XY plane. One side of the square lattice is parallel to the X-axis, and the other side is parallel to the Y-axis. At this time, a square unit constituting region R centered on the lattice point O of the square lattice can be set in a two-dimensional shape, covering multiple columns (x = 0, 1, 2, 3) along the X-axis and multiple rows (y = 0, 1, 2) along the Y-axis. Multiple different refractive index regions 12b are each provided in each unit constituting region R. The planar shape of the different refractive index regions 12b can be various shapes such as circles, similar to the first embodiment described above. Within a unit constitutive region R(x,y), the centroid G of regions 12b with different refractive indices is arranged separately from its corresponding lattice point O(x,y).

[0150] like Figure 8 As shown, the positions within the unit constitutive region R(x,y) are defined by the s-axis parallel to the X-axis and the t-axis parallel to the Y-axis, with the intersection of the s-axis and the t-axis (origin) being the lattice point O(x,y). In the unit constitutive region R(x,y), let φ(x,y) be the angle between the direction from the lattice point O(x,y) towards the centroid G and the s-axis. The x-component represents the position of the x-th lattice point O along the X-axis, and the y-component represents the position of the y-th lattice point O along the Y-axis. When the rotation angle φ(x,y) is 0°, the direction of the vector connecting the lattice point O(x,y) and the centroid G is aligned with the positive direction of the s-axis. Furthermore, let the length of the vector connecting the lattice point O(x,y) and the centroid G be r(x,y). In one example, r(x,y) is constant regardless of x and y (throughout the entire phase modulation layer 12B).

[0151] like Figure 7 As shown, in the phase modulation layer 12B, the rotation angle φ around the lattice point O of the centroid G of different refractive index regions 12b can be individually set for each unit constitutive region R according to the desired optical image. The rotation angle φ(x,y) in each unit constitutive region R(x,y) has a specific value for each position (unit constitutive region R) determined by the values ​​of the x and y components, but is not necessarily limited to being expressed by a specific function. That is, the rotation angle distribution φ(x,y) is determined by extracting the phase distribution from the complex amplitude distribution obtained by inverse Fourier transform of the desired optical image. In obtaining the complex amplitude distribution from the desired optical image, the reproducibility of the beam pattern can be improved by applying a repetitive algorithm such as the Gerchberg-Saxton (GS) method, which is commonly used in hologram generation calculations.

[0152] In this second embodiment, the light output from the UC layer 11 is confined between the first light-reflecting layer 13 and the second light-reflecting layer 14 and undergoes diffraction based on the phase modulation layer 12B, forming a predetermined pattern corresponding to the internal lattice structure of the phase modulation layer 12B. The laser light scattered within the phase modulation layer 12B is output to the outside via the second light-reflecting layer 14. At this time, the 0th order light is output in the thickness direction (Z direction) of the phase modulation layer 12B. In contrast, the +1 and -1 order lights are output in any direction in space, including the Z direction and directions inclined relative to the Z direction.

[0153] Figure 9 This is a diagram illustrating the relationship between an optical image obtained by imaging the output beam pattern of the optical device 10B according to the second embodiment and the rotation angle distribution φ(x,y) of the phase modulation layer 12B. The center Q of the output beam pattern is located in the Z direction from the center of the light output surface of the optical device 10B. Figure 9 This represents the four quadrants with center Q as the origin. Figure 9 In this example, the optical image is obtained in the first and third quadrants, but images can also be obtained in the second and fourth quadrants or all quadrants. In this second embodiment, as... Figure 9 As shown, an optical image that is point-symmetric about the origin can be obtained. For example, Figure 9 This indicates the case where the character "A" is diffracted as +1 order light in the 3rd quadrant, and the case where the pattern obtained by rotating the character "A" 180 degrees in the 1st quadrant is diffracted as -1 order light. In the case of rotationally symmetric optical images (e.g., cross, circle, double circle, etc.), they are observed as a single optical image when superimposed.

[0154] The optical image obtained by imaging the output beam pattern of the optical device 10B in the second embodiment includes at least one of the following: dots, straight lines, crosses, line drawings, lattice patterns, photographs, bar patterns, CG (computer graphics), and characters. Here, in order to obtain the desired optical image, the rotation angle distribution φ(x, y) of the different refractive index regions 12b of the phase modulation layer 12B is determined in the following order.

[0155] First, as a first prerequisite, in the XYZ Cartesian coordinate system defined by the Z-axis aligned with the normal direction and the XY plane, which includes mutually orthogonal X-axis and Y-axis aligned with a surface of the phase modulation layer 12B comprising multiple regions 12b with different refractive indices, an imaginary square lattice is set on the XY plane, consisting of regions R each having a square shape of M1 (an integer greater than 1) × N1 (an integer greater than 1).

[0156] As a second prerequisite, the coordinates (ξ, η, ζ) in the XYZ rectangular coordinate system are as follows: Figure 10 As shown, relative to the length r of the vector path and the tilt angle θ from the Z-axis tilt The rotation angle θ from the X-axis, determined in the XY plane. rot Defined spherical coordinates (r, θ) rot ,θ tilt ), satisfying the relationships expressed by the following equations (1) to (3). Wherein, Figure 10 It is used to explain the relationship between spherical coordinates (r, θ) rot ,θ tilt A graph showing the coordinate transformation from (ξ, η, ζ) to the XYZ Cartesian coordinate system. Through the coordinates (ξ, η, ζ), an optical image of the design can be represented on a specified plane set in the XYZ Cartesian coordinate system as real space.

[0157] [Number 1]

[0158] ξ=r sinθ tilt cosθ rot …(1)

[0159] [Number 2]

[0160] η = r sinθ tilt sinθ rot …(2)

[0161] [Number 3]

[0162] ζ=r cosθ tilt …(3)

[0163] The beam pattern corresponding to the optical image output from the optical device 10B is oriented towards an angle θ. tilt and θ rot When a set of bright spots in a specified direction is formed, the angle θ tilt and θ rot The coordinate values ​​kx on the Kx axis corresponding to the X-axis are converted into normalized wavenumbers as defined by the following equation (4), and the coordinate values ​​ky on the Ky axis corresponding to the Y-axis and orthogonal to the Kx axis are converted into normalized wavenumbers as defined by the following equation (5). The normalized wavenumber is the wavenumber that is normalized to 1.0, which corresponds to the lattice spacing of the imaginary square lattice. At this time, in the wavenumber space defined by the Kx axis and the Ky axis, a specific wavenumber range containing the beam pattern corresponding to the optical image is formed by M2 (an integer greater than or equal to 1) × N2 (an integer greater than or equal to 1) image regions FR, each of which is square. Here, the integer M2 does not necessarily have to be the same as the integer M1. Similarly, the integer N2 does not necessarily have to be the same as the integer N1. Furthermore, equations (4) and (5) are disclosed, for example, by the aforementioned non-patent document 2.

[0164] [Number 4]

[0165]

[0166] [Number 5]

[0167]

[0168] a: The lattice constant of a hypothetical square lattice

[0169] λ: Oscillation wavelength of optical device 10B

[0170] As a third prerequisite, in wavenumber space, the complex amplitude F(x,y) is obtained by performing a two-dimensional discrete Fourier inverse transform on the image region FR(kx,ky) specific to the coordinate components kx (integers above M2-1) in the Kx-axis direction and ky (integers above N2-1) in the Ky-axis direction, respectively, into a unit region R(x,y) on the XY plane specific to the coordinate components x (integers above M1-1) in the X-axis direction and y (integers above N1-1) in the Y-axis direction. The complex amplitude F(x,y) is given by equation (6) with j as the imaginary unit. Furthermore, this complex amplitude F(x,y) is defined by equation (7) with the amplitude term A(x,y) and the phase term P(x,y). Furthermore, as a fourth prerequisite, the unit constitutive region R(x,y) is defined by the s-axis and t-axis, which are parallel to the X-axis and Y-axis respectively and orthogonal to the lattice point O(x,y) that is the center of the unit constitutive region R(x,y).

[0171] [Number 6]

[0172]

[0173] [Number 7]

[0174] F(x,y)=A(x,y)×exp[jP(x,y)]…(7)

[0175] Under the aforementioned first to fourth conditions, the phase modulation layer 12B is configured to satisfy the following first and second conditions. Specifically, the first condition is that within a unit constitutive region R(x,y), the centroid G is arranged in a state separated from the lattice point O(x,y). Furthermore, the second condition is that, in a state where the length r(x,y) of the line segment from the lattice point O(x,y) to the corresponding centroid G is set to a common value in each of the M1 × N1 unit constitutive regions R, the angle φ(x,y) formed by the line segment connecting the lattice point O(x,y) and the corresponding centroid G with the s-axis satisfies the following relationship, corresponding regions 12b with different refractive indices are arranged within the unit constitutive region R(x,y).

[0176] φ(x,y)=C×P(x,y)+B

[0177] C: Proportionality constant, for example, 180 / π

[0178] B: is any constant, for example, 0.

[0179] Figure 11 This indicates that it is applied only within a specific region of the phase modulation layer. Figure 7 A top view of an example of a refractive index structure. Figure 11 In the example shown, a refractive index structure (e.g., for outputting the desired beam pattern) is formed inside the inner region RIN of the square. Figure 7 (Structure of the inner region RIN). On the other hand, in the outer region ROUT surrounding the inner region RIN, circular regions of different refractive indices with the same centroid are arranged at the lattice point positions of the square lattice. The lattice spacing of the imaginary square lattice is the same both inside the inner region RIN and in the outer region ROUT. In this structure, by distributing light within the outer region ROUT, it has the advantage of suppressing the generation of high-frequency noise (so-called window function noise) caused by abrupt changes in light intensity at the periphery of the inner region RIN. Furthermore, because light leakage in the in-plane direction can be suppressed, the conversion efficiency from excitation light to light Lout can be improved.

[0180] As a method to obtain the intensity distribution and phase distribution from the complex amplitude distribution obtained by performing a two-dimensional inverse Fourier transform, for example, the intensity (amplitude) distribution I(x,y) can be calculated using the abs function of the numerical analysis software "MATLAB" of MathWorks, and the phase distribution P(x,y) can be calculated using the angle function of MATLAB.

[0181] Here, we explain the points to note when using the commonly used Discrete Fourier Transform (or Fast Fourier Transform) for calculations when determining the configuration of different refractive index regions 12b by obtaining the rotation angle distribution φ(x,y) from the inverse Fourier transform result of the optical image. This is based on the desired optical image... Figure 12 The output beam pattern is calculated from the complex amplitude distribution obtained by the inverse Fourier transform of (a), as shown in... Figure 12 As shown in (b). When as Figure 12 (a) Figure 12 (b) When the space is divided into four quadrants, A1, A2, A3, and A4, in that way, Figure 12 (b) The first quadrant of the output beam pattern shows that Figure 12 (a) The pattern rotated 180 degrees in the first quadrant and Figure 12(a) The pattern after overlapping the patterns in the third quadrant. In the second quadrant of the beam pattern, the appearance is... Figure 12 (a) The pattern in the second quadrant rotated 180 degrees and Figure 12 (a) The pattern after overlapping the patterns in the fourth quadrant. The beam pattern appears in the third quadrant. Figure 12 (a) The pattern in the third quadrant rotated 180 degrees and Figure 12 (a) The pattern after overlapping the patterns in the first quadrant. The beam pattern appears in the fourth quadrant. Figure 12 (a) The pattern in quadrant 4 rotated 180 degrees and Figure 12 (a) The pattern after the patterns in the second quadrant overlap. At this time, the pattern rotated 180 degrees is the pattern formed by the -1 light component.

[0182] Therefore, when using an optical image that has a value only in the first quadrant as the optical image before the inverse Fourier transform (original optical image), the first quadrant of the original optical image is displayed in the third quadrant of the obtained beam pattern, and a pattern that rotates the first quadrant of the original optical image by 180 degrees is displayed in the first quadrant of the obtained beam pattern.

[0183] Figure 13 (a)~ Figure 13 (d) shows an example of a beam pattern (optical image) output from a GaAs-based S-iPM laser in the near-infrared band that utilizes the same principle as in the second embodiment. Figure 13 (a)~ Figure 13 (d) Their respective centers are located in the Z direction from the center of the output surface of the S-iPM laser. For example, these... Figure 13 (a)~ Figure 13 As shown in (d), the S-iPM laser outputs: a +1 order light comprising a first optical image portion E1 output in a first direction inclined relative to an axis extending along the Z direction from the center of the light output surface; a -1 order light comprising a second optical image portion E2 output in a second direction symmetrical about the first direction and rotationally symmetrical about the first optical image portion E1 about the same axis; and a 0 order light E3 traveling along the same axis. This is also true in the optical device 10B of this second embodiment.

[0184] In the second embodiment, light in the second wavelength region output from the UC layer 11 is confined between the first light-reflecting layer 13 and the second light-reflecting layer 14 and subjected to diffraction based on the phase modulation layer 12B. As a result, a predetermined pattern corresponding to the internal lattice structure of the phase modulation layer 12B is formed. In the phase modulation layer 12B, the centroids of multiple regions 12b with different refractive indices have rotation angles φ(x,y) around the lattice points of an imaginary square lattice, set according to each region 12b with different refractive indices. In this case, the centroids G of the multiple regions 12b with different refractive indices are located at the lattice points of the square lattice (see the case where the centroids G of the multiple regions 12b with different refractive indices are located at the lattice points of the square lattice). Figure 2 Compared to the previous method, the light intensity of the 0th order light output in the thickness direction of the phase modulation layer 12B (in other words, the Z direction perpendicular to the light output surface of the optical device 10B) is reduced, while the light intensity of the higher order light output in the direction inclined relative to this direction, such as the +1st and -1st order light, is increased. Furthermore, by individually setting the rotation angle φ(x,y) around the lattice point of the centroid G of each different refractive index region 12b according to the desired optical image, the phase of the light can be independently modulated for each different refractive index region 12b. As a result, optical images of arbitrary spatial shapes can be output in the Z direction perpendicular to the light output surface and in the direction inclined relative to the Z direction. This optical image (output light Lout) is output to the outside of the optical device 10B through the second light reflection layer 14 and the dichroic mirror 16.

[0185] In the optical device 10B of the second embodiment, similar to the first embodiment described above, it can output light Lout of shorter wavelengths, such as green and blue, based on excitation light of relatively long wavelengths, such as near-infrared light and red light. Furthermore, since it is not necessary to use nitride semiconductors such as GaN in the phase modulation layer 12B, the material selection for the phase modulation layer 12B is highly flexible, thus improving the light confinement coefficient of the phase modulation layer 12B. Therefore, according to this second embodiment, an optical device 10B can be provided as a practical phase-modulated light-emitting element capable of outputting two-dimensional optical images in a relatively short wavelength region, such as the visible region. The optical device 10B of the second embodiment can be manufactured using the same process as the optical device 10A of the first embodiment.

[0186] (Third Implementation)

[0187] The S-iPM laser is not limited to the structure of the second embodiment described above. For example, even the structure of the phase modulation layer in the third embodiment can be appropriately implemented as an S-iPM laser. Figure 14 This is a top view of the phase modulation layer 12C, which serves as a resonant mode forming layer, in the optical device of the third embodiment. Furthermore, Figure 15This is a diagram showing the positional relationship of different refractive index regions 12b in the phase modulation layer 12C.

[0188] like Figure 14 and Figure 15 As shown, in the unit constitutive region R(x,y) of the phase modulation layer 12C, the centroids G of each region 12b with different refractive indices are arranged on a straight line D. Straight line D passes through the corresponding lattice point O(x,y) of the unit constitutive region R(x,y) and is inclined relative to each edge of the square lattice. In other words, straight line D is inclined relative to both the X-axis and Y-axis. The inclination angle of straight line D relative to one side (X-axis) of the square lattice is θ. The inclination angle θ is constant within the phase modulation layer 12C. The inclination angle θ satisfies 0° < θ < 90°, and in one example θ = 45°. Alternatively, the inclination angle θ satisfies 180° < θ < 270°, and in one example θ = 225°. When the inclination angle θ satisfies 0° < θ < 90° or 180° < θ < 270°, straight line D extends from the first quadrant to the third quadrant of the coordinate plane defined by the X-axis and Y-axis. Alternatively, the tilt angle θ satisfies 90° < θ < 180°, in one example θ = 135°. Or, the tilt angle θ satisfies 270° < θ < 360°, in one example θ = 315°. When the tilt angle θ satisfies 90° < θ < 180° or 270° < θ < 360°, the straight line D extends from the second quadrant to the fourth quadrant of the coordinate plane defined by the X and Y axes. Thus, the tilt angle θ is an angle other than 0°, 90°, 180°, and 270°. By employing such a tilt angle θ, it is possible to facilitate both the light waves traveling in the X-axis direction and the light waves traveling in the Y-axis direction within the light output beam. Here, let the distance between the lattice point O(x,y) of the unit constituting region R(x,y) and the centroid G be r(x,y). The x-component represents the position of the x-th lattice point O on the X-axis, and the y-component represents the position of the y-th lattice point O on the Y-axis. When the distance r(x,y) is positive, the barycenter G is located in the first quadrant (or the second quadrant). When the distance r(x,y) is negative, the barycenter G is located in the third quadrant (or the fourth quadrant). When the distance r(x,y) is 0, the lattice point O coincides with the barycenter G.

[0189] Figure 14The distance r(x,y) between the centroid G of each of the different refractive index regions 12b and the corresponding lattice point O(x,y) in the unit constitutive region R(x,y) is individually set for each different refractive index region 12b according to the desired optical image. The distribution of distance r(x,y) has a specific value at each position (unit constitutive region) determined by the values ​​of the x and y components, but is not necessarily limited to being represented by a specific function. The distribution of distance r(x,y) is determined by extracting the phase distribution value from the complex amplitude distribution obtained by performing an inverse Fourier transform on the desired optical image. That is, in Figure 15 When the phase P(x,y) at a certain coordinate (x,y) is P0, the distance r(x,y) is set to 0. When the phase P(x,y) is π+P0, the distance r(x,y) is set to its maximum value R0. When the phase P(x,y) is -π+P0, the distance r(x,y) is set to its minimum value -R0. Thus, relative to the intermediate phase P(x,y), the distance r(x,y) is set as r(x,y) = {P(x,y)-P0}×R0 / π. Here, the initial phase P0 can be arbitrarily set. When the lattice spacing of the square lattice is a, the maximum value R0 of r(x,y) is, for example, within the range of the following formula.

[0190] [Number 8]

[0191]

[0192] In particular, when determining the complex amplitude distribution based on the desired optical image, the reproducibility of the beam pattern can be improved by applying an iterative algorithm such as the GS method, which is commonly used in hologram generation calculations.

[0193] In this third embodiment, the desired optical image can be obtained by determining the distribution of the distances r(x,y) of the different refractive index regions 12b of the phase modulation layer 12C in the following order. That is, under the first to fourth prerequisites described in the second embodiment above, the phase modulation layer 12C is configured to satisfy the following condition: The corresponding different refractive index regions 12b are arranged within a unit constitutive region R(x,y) such that the distance r(x,y) from the lattice point O(x,y) to the centroid G of the corresponding different refractive index region 12b satisfies the following formula.

[0194] r(x,y)=C×(P(x,y)-P0)

[0195] C: Proportioning constant, for example, R0 / π

[0196] P0: Any constant, for example, 0.

[0197] That is, the distance r(x,y) is set to 0 when the phase P(x,y) at a certain coordinate (x,y) is P0, set to the maximum value R0 when the phase P(x,y) is π+P0, and set to the minimum value -R0 when the phase P(x,y) is -π+P0. To obtain the desired optical image, an inverse discrete Fourier transform is performed on the optical image, and the distribution of distances r(x,y) corresponding to the phase P(x,y) with its complex amplitude is assigned to multiple regions 12b with different refractive indices. Alternatively, the phase P(x,y) and the distance r(x,y) can be proportional to each other.

[0198] In this third embodiment, it may also be applied only in a specific region of the phase modulation layer 12C. Figure 14 The refractive index structure. For example, it can also be like... Figure 11 As shown in the example, a refractive index structure for outputting the target beam pattern is formed inside the inner region RIN of the square (e.g., Figure 14 (Structure of the structure). In this case, in the outer region ROUT surrounding the inner region RIN, circular regions of different refractive indices with the same centroid are arranged at the lattice point positions of the square lattice. The lattice spacing of the imaginary square lattice is the same both inside the inner region RIN and in the outer region ROUT. With this structure, by distributing light also in the outer region ROUT, the generation of high-frequency noise (so-called window function noise) caused by the abrupt change in light intensity at the periphery of the inner region RIN can be suppressed. Furthermore, light leakage in the in-plane direction can be suppressed, thus improving the conversion efficiency from excitation light to light Lout.

[0199] As a method for obtaining the intensity and phase distributions based on the complex amplitude distribution obtained through the inverse Fourier transform, for example, the intensity distribution I(x,y) can be calculated using the abs function of the numerical analysis software "MATLAB" from MathWorks, and the phase distribution P(x,y) can be calculated using the angle function of MATLAB. When determining the distance r(x,y) of each different refractive index region 12b based on the phase distribution P(x,y) obtained from the inverse Fourier transform result of the optical image, the points to note when using the commonly used discrete Fourier transform (or fast Fourier transform) for calculation are the same as in the second embodiment described above.

[0200] In the third embodiment, light in the second wavelength region output from the UC layer 11 is confined between the first light-reflecting layer 13 and the second light-reflecting layer 14 and subjected to diffraction based on the phase modulation layer 12C. As a result, a predetermined pattern corresponding to the internal lattice structure of the phase modulation layer 12C is formed. In the phase modulation layer 12C, the centroids G of multiple regions 12b with different refractive indices are arranged on a straight line D that passes through the lattice point O of an imaginary square lattice and is inclined relative to the square lattice. Thus, for each unit constituting region R(x,y), the distance r(x,y) between the centroid G of the different refractive index regions 12b and the corresponding lattice point O(x,y) is individually set according to the optical image. In this case, when the centroids G of multiple regions 12b with different refractive indices are located on the lattice point O of the square lattice (see...) Figure 2 Compared to the previous method, the light intensity of the 0th order light output in the thickness direction of the phase modulation layer 12C (in other words, the Z direction perpendicular to the light output surface of the optics) is reduced, while the light intensity of the higher order light output in the direction inclined relative to this direction, such as the +1st and -1st order light, is increased. Furthermore, by individually setting the distance r(x,y) between the centroid G of each different refractive index region 12b and the corresponding lattice point O according to the desired optical image, the phase of the light can be independently modulated for each different refractive index region 12b, outputting an optical image of arbitrary shape in the Z direction perpendicular to the light output surface and in the direction inclined relative to the Z direction. This optical image (output light Lout) is output to the outside of the optics through the second light reflection layer 14 and the dichroic mirror 16.

[0201] The optical device of the third embodiment, like those of the first and second embodiments described above, can output light (Lout) with shorter wavelengths, such as green and blue, based on excitation light with relatively long wavelengths, such as near-infrared and red light. Furthermore, since it is not necessary to use nitride semiconductors such as GaN in the phase modulation layer 12C, the material selection for the phase modulation layer 12C is highly flexible, thus improving the light confinement coefficient of the phase modulation layer 12C. Therefore, according to this third embodiment, an optical device can be provided as a practical phase-modulated light-emitting element capable of outputting two-dimensional optical images in a relatively short wavelength region, such as the visible region. The optical device of the third embodiment can be manufactured using the same process as the optical device 10A of the first embodiment.

[0202] (First variation)

[0203] Figure 16This is a diagram showing the cross-sectional structure of the light-emitting device 1C of the first modification. The light-emitting device 1C of this first modification has an optical device 10C instead of the optical device 10A of the first embodiment. The structure of the excitation light source 20A is the same as in the first embodiment. In addition to the structure of the optical device 10A of the first embodiment, the optical device 10C of the first modification also has a diffractive optical element (DOE) 17. The diffractive optical element 17 is disposed at a position where the second light-reflecting layer 14 is sandwiched between it and the UC layer 11. Figure 16 In this example, the diffractive optical element 17 is formed on the side opposite to the side of the substrate 15 where the second light-reflecting layer 14 is formed. Therefore, Figure 1 The dichroic mirror 16 shown cannot be formed on the surface of the substrate 15. However, the dichroic mirror 16 formed on other substrates can also be optically coupled to the diffractive optical element 17.

[0204] The diffractive optical element 17 is an optical device that spatially controls the phase distribution of transmitted light by utilizing the irregularities formed on the surface of a light-transmitting substrate (e.g., substrate 15). (In this case, the depth (height) of the irregularity is independently set for each unit constituting region R arranged in a two-dimensional shape.) In this first modification, for example, the diffractive optical element 17 can be provided by forming irregularities on the surface of substrate 15.

[0205] According to the first modification, by pre-forming a phase distribution based on an optical image of arbitrary shape in the diffractive optical element 17, the laser light output from the second wavelength region through the second light-reflecting layer 14 can be converted into an optical image of arbitrary shape. Therefore, according to the first modification, an optical image of arbitrary shape in the second wavelength region can be output. The optical device 10C of the first modification can be appropriately manufactured by performing the process of forming the diffractive optical element 17 on another surface of the substrate 15 instead of the process of forming a dielectric multilayer film as a dichroic mirror 16 in the manufacturing process of the optical device 10A of the first embodiment. The diffractive optical element 17 is formed, for example, by coating an electron beam resist on the surface of the substrate 15, patterning it by electron beam scanning, and then performing dry etching on the surface of the substrate 15. A substrate different from the substrate 15, i.e., a substrate on which the diffractive optical element 17 is formed, can also be attached to the substrate 15.

[0206] (Second variation)

[0207] Figure 17This is a cross-sectional view showing the manufacturing process of the light-emitting device 1D in the second modification. The light-emitting device 1D in this second modification includes an optical device 10A1 and an excitation light source 20A. The optical device 10A1 does not have a PC layer 12A; instead, different refractive index regions 11b are formed in the UC layer 11, whereby a portion of the UC layer 11 in the thickness direction functions as a PC layer, which differs from the optical device 10A in the first embodiment. However, the other structures of the optical device 10A1 are the same as those in the optical device 10A of the first embodiment. In this second modification, after forming a second light-reflecting layer 14 and a dichroic mirror 16 on both sides of the substrate 15, an upconversion material dispersed in resin is coated on the second light-reflecting layer 14. Next, a PC layer is formed by forming different refractive index regions 11b in the resin layer using nanoimprinting or the like. Then, a first light-reflecting layer 13 is formed on the back side 21b of the semiconductor substrate 21, and the first light-reflecting layer 13 and the PC layer are bonded together. As the excitation source, it is not limited to the excitation source 20A for PCSELs, but can also be used for various other surface-emitting excitation sources. The distribution of different refractive index regions 11b is not limited to the distribution of the first embodiment, but can also be the distribution of the second or third embodiment (see reference). Figure 7 or Figure 14 Furthermore, in this second variation, although the first light-reflecting layer 13 and the PC layer are bonded together, they can also be separated from each other. In this case, excitation light is spatially propagated from the first light-reflecting layer 13 and supplied to the UC layer 11.

[0208] (3rd variation)

[0209] Figure 18 This is a diagram showing the cross-sectional structure of the light-emitting device 1E in the third modification. The light-emitting device 1E in this third modification replaces the excitation source 20A of the first modification with an excitation source 20B. The structure of the optical device 10C is the same as in the first modification. The excitation source 20B of the third modification is a vertically cambered surface-emitting laser (VCSEL), having a semiconductor substrate 21, a first DBR layer 29, an active layer 22, a second DBR layer 30, a contact layer 26, a first electrode 27, and a second electrode 28.

[0210] The first DBR layer 29 and the second DBR layer 30 have a structure for a distributed Bragg reflector (DBR), specifically formed by alternately stacking a first semiconductor layer and a second semiconductor layer with a different refractive index. These first and second semiconductor layers can be configured with a thickness of λ / 4nd (nd: the refractive index of the corresponding semiconductor layer) relative to the laser wavelength λ, resulting in phase-consistent reflected light and high reflectivity. The first DBR layer 29 is disposed on the main surface 21a of the semiconductor substrate 21, and in one example, is in contact with the main surface 21a of the semiconductor substrate 21. The second DBR layer 30 is disposed on the first DBR layer 29. An active layer 22 is disposed between the first DBR layer 29 and the second DBR layer 30. The thickness of the active layer 22 can be set to an integer multiple of λ / 2na (na: the effective refractive index of the active layer). By positioning a quantum well with optical gain within the electric field, mode gain can be improved and oscillation threshold current can be reduced. Contact layer 26 is disposed on the second DBR layer 30. The band gaps of the first DBR layer 29 and the second DBR layer 30 are larger than the band gap of the active layer 22. The thickness directions of the semiconductor substrate 21, active layer 22, first DBR layer 29, second DBR layer 30 and contact layer 26 are aligned with the Z direction.

[0211] The first electrode 27 is a metal electrode disposed on the back surface 21b of the semiconductor substrate 21. The second electrode 28 is a metal electrode disposed on the contact layer 26. The materials and shapes of the first electrode 27 and the second electrode 28 are the same as those of the excitation light source 20A in the first embodiment. The contact layer 26 located outside the second electrode 28 can be removed when viewed from above. In this case, since it is possible to suppress current injection into unwanted areas, current can be efficiently injected into the light-emitting portion (active layer 22).

[0212] In one example, the semiconductor substrate 21 is a GaAs substrate. The first DBR layer 29, the active layer 22, the second DBR layer 30, and the contact layer 26 are made of GaAs-based semiconductors. Furthermore, the first DBR layer 29 is an AlGaAs layer. The active layer 22 has a multiple quantum well structure (barrier layer: AlGaAs / quantum well layer: InGaAs). The second DBR layer 30 is an AlGaAs layer. The contact layer 26 is a GaAs layer.

[0213] The first DBR layer 29 is given the same conductivity type as the semiconductor substrate 21, while the second DBR layer 30 and contact layer 26 are given the opposite conductivity type to the semiconductor substrate 21. In one example, the semiconductor substrate 21 and the first DBR layer 29 are n-type, and the second DBR layer 30 and contact layer 26 are p-type. The impurity concentration is, for example, 1 × 10⁻⁶. 16 ~1×1021 / cm 3 In the intrinsic (type i) form without the intentional addition of any impurities, the impurity concentration is 1 × 10⁻⁶. 16 / cm 3 The active layer 22 is not limited to intrinsic (type i) and can also be doped.

[0214] The excitation light source 20B of the third modification operates as follows. When a driving current is supplied between the first electrode 27 and the second electrode 28, electron and hole recombination occurs within the active layer 22, and light in the first wavelength region (e.g., the near-infrared region) is output from the active layer 22. This light resonates in the Z direction between the first DBR layer 29 and the second DBR layer 30, causing laser oscillation and generating laser light as excitation light. A portion of this laser light passes through the first DBR layer 29 and is output from the back surface 21b of the semiconductor substrate 21 through the opening 27a to the optical device 10C.

[0215] Alternatively, as in the third modification, the excitation source can be a VCSEL. In this case, excitation light can be appropriately supplied to the UC layer 11 of the optical device 10C. The light-emitting device 1E can also replace the optical device 10C and have the optical device 10A of the first embodiment, the optical device 10B of the second embodiment, or the optical device of the third embodiment. Furthermore, as in the second modification, the optical device can be separated from the excitation source and optically coupled.

[0216] (4th variation)

[0217] Figure 19 This is a diagram showing the cross-sectional structure of the light-emitting device 1F of the fourth modification. This fourth modification of the light-emitting device 1F includes an optical device 10D, an excitation light source 201, and a spatial light modulator 40. The optical device 10D has a structure that removes the dichroic mirror 16 from the optical device 10A of the first embodiment, but it may also include the dichroic mirror 16. Furthermore, the size of the optical device 10D viewed from the Z-direction is significantly larger than the size of the optical device 10A of the first embodiment viewed from the Z-direction.

[0218] The excitation light source 201 is integrated with the optical device 10D and supplies excitation light to the UC layer 11. The excitation light source 201 includes a plurality of excitation light sources 20A. Similar to the first embodiment, these excitation light sources 20A are PCSELs and are disposed at a position where the first light-reflecting layer 13 is sandwiched between the excitation light source 20A and the UC layer 11. Furthermore, these excitation light sources 20A are arranged in a one-dimensional or two-dimensional configuration along the surface 13a of the first light-reflecting layer 13. The back surface 21b of the semiconductor substrate 21 of these excitation light sources 20A faces the surface 13a of the first light-reflecting layer 13 through a gap formed by the opening 27a of the first electrode 27. A slit 33 for electrical separation is formed at the boundary of adjacent excitation light sources 20A. The semiconductor substrate 21 may also be common among the plurality of excitation light sources 20A. In this case, the excitation light source 201 is an array of laser elements consisting of a plurality of PCSELs formed on a common semiconductor substrate 21.

[0219] The spatial light modulator 40 is optically coupled to the optical device 10D and is positioned with the second light-reflecting layer 14 sandwiched between it and the UC layer 11. The spatial light modulator 40, for example, has a light-transmitting structure. Figure 19 In this example, the spatial light modulator 40 is disposed on the opposite side of the second light-reflecting layer 14 relative to the substrate 15. The spatial light modulator 40 can be integrated with the optical device 10D or disposed separately from the optical device 10D.

[0220] The spatial light modulator 40 has a plurality of pixels arranged in a two-dimensional pattern. By presenting a hologram on these pixels, the phase of the laser Lout1 output from the optical device 10D is modulated independently for each pixel. The spatial light modulator 40 has, for example, a liquid crystal type structure. When the spatial light modulator 40 is a liquid crystal type, individual voltages constituting the hologram are applied to the electrodes of the plurality of pixels arranged in a two-dimensional pattern. Thus, the magnitude of the electric field applied to the liquid crystal layer is controlled for each pixel. The optical path length in the liquid crystal layer of each pixel varies accordingly with the magnitude of the electric field. Therefore, the phase of the light can be modulated independently for each pixel. The spatial light modulator 40 is not limited to a liquid crystal type; various types of spatial light modulators can be used. The spatial light modulator 40 outputs an optical image Lout2 after phase modulation using a hologram.

[0221] According to the fourth modification, by presenting a phase pattern based on an optical image of arbitrary shape in the spatial light modulator 40, the laser Lout1 output through the second light reflection layer 14 in the second wavelength region can be converted into an optical image Lout2 of arbitrary shape. Therefore, according to the fourth modification, an optical image Lout2 of arbitrary shape in the second wavelength region can be output. Furthermore, by causing the phase pattern presented by the spatial light modulator 40 to change over time, the optical image Lout2 can also be dynamically changed.

[0222] Furthermore, as in the fourth modification, the excitation source 201 may include a plurality of excitation sources 20A, which are arranged in a one-dimensional or two-dimensional manner along the surface 13a of the first light-reflecting layer 13. Thus, the light transmittance of the first light-reflecting layer 13 in the wavelength region (first wavelength region) of the excitation light may be greater than the light transmittance of the first light-reflecting layer 13 in the emission wavelength region (second wavelength region) of the UC layer 11. In this case, since the excitation light output from the excitation source 201 is supplied to the UC layer 11 through the first light-reflecting layer 13, laser Lout1 in the second wavelength region can be appropriately output from the optical device 10D. Furthermore, according to the light-emitting device 1F of the fourth modification, since the excitation light is generated using a plurality of excitation sources 20A arranged in a one-dimensional or two-dimensional manner, the area of ​​the optical device 10D viewed from the light output direction can be made larger. Therefore, the area of ​​the optical image Lout2 output from the light-emitting device 1F can be made larger.

[0223] In the manufacture of the light-emitting device 1F of the fourth modification, after the steps of forming the first electrode 27 and the second electrode 28 of the first embodiment, the element is separated by forming a slit 33. Furthermore, instead of forming a dielectric multilayer film serving as a dichroic mirror 16 on the other side of the substrate 15, a step of configuring the spatial light modulator 40 is performed. Additionally, a first light-reflecting layer 13, a PC layer 12A, and a UC layer 11 are formed on one side of a light-transmitting substrate (e.g., a quartz substrate), and the back side of this substrate is bonded to the first electrode 27.

[0224] (5th variation)

[0225] Figure 20This is a cross-sectional view showing the manufacturing process of the light-emitting device 1G in the fifth modification. The light-emitting device 1G includes an optical device 10E and an excitation light source 201. The optical device 10E does not have a PC layer 12A; instead, different refractive index regions 11b are formed in the UC layer 11, thereby making a portion of the UC layer 11 in the thickness direction function as a PC layer, which differs from the optical device 10D in the fourth modification. The other structures of the optical device 10E are the same as those of the optical device 10D in the fourth modification. In the fifth modification, after forming a second light-reflecting layer 14 on one side of the substrate 15, an upconversion material dispersed in resin is coated on the second light-reflecting layer 14. Next, a PC layer is formed by forming different refractive index regions 11b in the resin layer using nanoimprinting or the like. Then, a first light-reflecting layer 13 is formed on one side of a light-transmitting substrate 18, and the first light-reflecting layer 13 and the PC layer are bonded. Furthermore, the other side of the substrate 18 is bonded to a first electrode 27. Finally, the spatial light modulator 40 is configured. The distribution of different refractive index regions 11b is not limited to the distribution in the first embodiment, but may also be the distribution in the second or third embodiment (see [reference]). Figure 7 or Figure 14 Furthermore, in this fifth variation, the first light-reflecting layer 13 is bonded to the PC layer, but they can also be separated from each other. In this case, excitation light is spatially propagated from the first light-reflecting layer 13 and supplied to the UC layer 11.

[0226] (Sixth variation)

[0227] Figure 21 This is a diagram showing the cross-sectional structure of the light-emitting device 1G in the sixth modification. In addition to the structure of the light-emitting device 1F in the fourth modification, the sixth modification 1G also includes a lens 41 disposed to the side of the optical device 10D (in the direction intersecting the Z direction). Thus, excitation light Lex1 is supplied to the UC layer 11 from the side of the optical device 10D via the lens 41. The excitation light Lex1 is light emitted from an excitation source (e.g., a laser diode or PCSEL) different from the excitation source 201. The wavelength of the excitation light Lex1 is equal to the wavelength of the excitation light emitted from the excitation source 201. Alternatively, as in this sixth modification, an excitation light Lex1 different from the excitation light supplied from the excitation source 201 may also be supplied to the UC layer 11. In this case, the density of the excitation light supplied to the UC layer 11 increases, and the luminous intensity of the light emitted from the UC layer 11 becomes greater, thus easily exceeding the oscillation threshold of the optical device 10D.

[0228] (Seventh variation)

[0229] Figure 22This is a diagram showing the cross-sectional structure of the light-emitting device 1H in the seventh modification. The light-emitting device 1H in this seventh modification replaces the excitation source 201 of the third modification by including an excitation source 202. The excitation source 202 is integrated with the optical device 10D and supplies excitation light to the UC layer 11. The excitation source 202 is configured to include a plurality of excitation sources 20C. These excitation sources 20C are PCSELs and are disposed on the opposite side of the UC layer 11 relative to the first light-reflecting layer 13. Furthermore, these excitation sources 20C are arranged in a one-dimensional or two-dimensional configuration along the surface 13a of the first light-reflecting layer 13.

[0230] The excitation light source 20C has a first electrode 31 instead of the first electrode 27 of the excitation light source 20A in the first embodiment. The other structures of the excitation light source 20C are the same as those of the excitation light source 20A. The first electrode 31 is made of a transparent conductive film that is transparent to at least the wavelength of the excitation light, and is disposed over the entire surface of the back surface 21b of the semiconductor substrate 21. Thus, the first light-reflecting layer 13 of the optical device 10D faces the first electrode 31 and, in one example, contacts the first electrode 31. Various materials can be used for the transparent conductive film, such as indium tin oxide (ITO), zinc oxide-based transparent conductive films, and tin oxide-based transparent conductive films.

[0231] In this seventh modification, a driving current is supplied between the first electrode 31 and the second electrode 28. The excitation light generated in each excitation source 20C then passes through the first electrode 31 to the first light-reflecting layer 13, and is further supplied to the UC layer 11 through the first light-reflecting layer 13. The semiconductor substrate 21 may also be common in the multiple excitation sources 20C. In this case, the excitation source 202 is an array of laser elements consisting of multiple PCSELs formed on a common semiconductor substrate 21.

[0232] (8th variation)

[0233] Figure 23 This is a cross-sectional view showing the structure of the light-emitting device 1J in the eighth modification. The light-emitting device 1J in this eighth modification includes an optical device 10A having the same structure as in the first embodiment, and an excitation light source 42. The excitation light source 42 is disposed separately from the optical device 10A, supplying excitation light Lex2 in the first wavelength region to the UC layer 11 of the optical device 10A. Therefore, the excitation light source 42 is spatially optically coupled to the UC layer 11 of the optical device 10A. Furthermore, by optically coupling with the side of the UC layer 11, the excitation light Lex2 is bypassed by the first light-reflecting layer 13 and the second light-reflecting layer 14, and supplied to the UC layer 11. Therefore, neither the first light-reflecting layer 13 nor the second light-reflecting layer 14 needs to have light transmittance characteristics for the excitation light Lex2; therefore, for example, other light-reflecting films such as metal films can be used instead of dielectric multilayer films as the first light-reflecting layer 13.

[0234] (9th variation)

[0235] A modified example of the phase modulation layer 12B according to the second embodiment described above will be described in detail. In this ninth modified example, the lattice spacing a of the hypothetical square lattice and the emission wavelength λ of the UC layer 11 satisfy the condition for M-point oscillation. Furthermore, when considering the inverted lattice space (wavenumber space) in the phase modulation layer 12B, phase modulation based on the rotation angle distribution φ(x,y) is received, forming in-plane wavenumber vectors representing standing waves that respectively contain wavenumber extensions corresponding to the angular extensions of the light forming the optical image. Thus, at least one of these in-plane wavenumber vectors has a magnitude less than 2π / λ (ray). These aspects will be described in detail below.

[0236] First, for comparison, a photonic crystal laser (PCSEL) oscillating at point Γ in inverted lattice space will be described. The PCSEL has an active layer and a PC layer with multiple regions of different refractive indices arranged periodically in a two-dimensional configuration. In a plane perpendicular to the thickness direction of the PC layer, the PCSEL forms a standing wave with an oscillation wavelength corresponding to the arrangement period of the different refractive index regions, and outputs laser light along the normal direction of the main surface of the semiconductor substrate. Furthermore, for Γ-point oscillation, the lattice spacing 'a' of the hypothetical square lattice, the emission wavelength λ of the UC layer 11, and the equivalent refractive index (effective refractive index) n of the mode must satisfy the condition: λ = na.

[0237] Figure 24 This is a top view representing the inverted lattice space (wavenumber space) of the PC layer of a PCSEL oscillating at point Γ. Figure 24 This represents the case where multiple regions with different refractive indices are located at lattice points in a square lattice. Figure 24 Point P in the diagram represents the inverted lattice point. Furthermore, Figure 24 Arrow B1 represents the fundamental reciprocal lattice vector, and arrow B2 represents twice the fundamental reciprocal lattice vector B1. Furthermore, arrows K1, K2, K3, and K4 represent four in-plane wavenumber vectors. These four in-plane wavenumber vectors K1, K2, K3, and K4 combine with each other through diffraction at 90° and 180°, forming a standing wave state. Here, mutually orthogonal Γ-X and Γ-Y axes are defined in the reciprocal lattice space. The Γ-X axis is parallel to one side of the square lattice, and the Γ-Y ​​axis is parallel to the other side. An in-plane wavenumber vector is a vector projected onto the Γ-X·Γ-Y plane. That is, in-plane wavenumber vector K1 faces the positive direction of the Γ-X axis, in-plane wavenumber vector K2 faces the positive direction of the Γ-Y ​​axis, in-plane wavenumber vector K3 faces the negative direction of the Γ-X axis, and in-plane wavenumber vector K4 faces the negative direction of the Γ-Y ​​axis. According to... Figure 24It is evident that in a PCSEL oscillating at the Γ point, the magnitudes of the in-plane wavenumber vectors K1 to K4 (i.e., the magnitudes of the standing waves in the in-plane direction) are equal to the magnitude of the fundamental inverted lattice vector B1. The magnitude k of the in-plane wavenumber vectors K1 to K4 is given by the following equation (9).

[0238] [Number 9]

[0239]

[0240] Figure 25 It is a three-dimensional observation Figure 24 The diagram shows a three-dimensional representation of the inverted lattice space. Figure 25 The Z-axis represents the direction orthogonal to the Γ-X and Γ-Y axes. This Z-axis is... Figure 1 The Z-axis shown is the same. For example... Figure 25 As shown, in a PCSEL oscillating at point Γ, the wavenumber in the in-plane direction becomes 0 due to diffraction, resulting in diffraction in the direction perpendicular to the plane (Z-axis direction) (arrow K5 in the figure). Therefore, the laser is essentially output in the Z-axis direction.

[0241] Next, the PCSEL oscillating at point M will be explained. For oscillation at point M, the lattice spacing a of the hypothetical square lattice, the emission wavelength λ of the UC layer 11, and the equivalent refractive index n of the mode satisfy the condition: λ = (2 1 / 2 )n×a is sufficient. Figure 26 This is a top view representing the inverted lattice space (wavenumber space) of the PC layer of a PCSEL oscillating at point M. Figure 26 It also indicates the case where multiple regions with different refractive indices are located at lattice points of a square lattice. Figure 26 Point P in the diagram represents the inverted lattice point. Furthermore, Figure 26 Arrow B1 in the image indicates that... Figure 24 Using the same fundamental reciprocal lattice vectors, arrows K6, K7, K8, and K9 represent four in-plane wavenumber vectors. Here, the Γ-M1 and Γ-M2 axes, orthogonal to each other, are defined in reciprocal lattice space. The Γ-M1 axis is parallel to one diagonal direction of the square lattice, and the Γ-M2 axis is parallel to the other diagonal direction of the square lattice. An in-plane wavenumber vector is a vector projected onto the Γ-M1·Γ-M2 plane. That is, in-plane wavenumber vector K6 points towards the positive direction of the Γ-M1 axis. In-plane wavenumber vector K7 points towards the positive direction of the Γ-M2 axis. In-plane wavenumber vector K8 points towards the negative direction of the Γ-M1 axis. In-plane wavenumber vector K9 points towards the negative direction of the Γ-M2 axis. Figure 26 It is evident that in the PCSEL oscillating at point M, the magnitudes of the in-plane wavenumber vectors K6 to K9 (i.e., the magnitudes of the standing waves in the in-plane direction) are smaller than the magnitude of the fundamental inverted lattice vector B1. The magnitude k of the in-plane wavenumber vectors K6 to K9 is given by the following equation (10).

[0242] [Number 10]

[0243]

[0244] Diffraction occurs in the direction of the sum of the wavenumber vectors K6 to K9 in the reciprocal lattice vectors (with a magnitude of 2mπ / a, where m is an integer). However, in a PCSEL with M-point oscillation, the wavenumber in the in-plane direction cannot be zero due to diffraction, and diffraction in the direction perpendicular to the plane (Z-axis direction) is not produced. Therefore, since no laser is output in the direction perpendicular to the plane, M-point oscillation is usually not used in PCSELs.

[0245] Next, the S-iPM laser oscillating at point Γ will be described. The conditions for oscillation at point Γ are the same as those for the PCSEL described above. Figure 27 This is a top view showing the inverted lattice space of the phase modulation layer of an S-iPM laser oscillating at the Γ point. The fundamental inverted lattice vector B1 is the same as that of the PCSEL oscillating at the Γ point (see reference). Figure 24 However, the in-plane wavenumber vectors K1 to K4 are subjected to phase modulation based on the rotation angle distribution φ(x,y), and each has a wavenumber spread SP corresponding to the spread angle of the optical image. The wavenumber spread SP is centered on the front end of each in-plane wavenumber vector K1 to K4 of the PCSEL oscillating at Γ point, and the lengths of the sides in the x-axis and y-axis directions can be expressed as 2Δkx. max 、2Δky max The rectangular region. Through this wavenumber extension SP, the wavenumber vectors K1 to K4 in each surface are extended in a rectangular range of (Kix + Δkx, Kiy + Δky) (i = 1 to 4, Kix is ​​the x-direction component of vector Ki, and Kiy is the y-direction component of vector Ki). Here, it is called -Δkx. max ≦Δkx≦Δkx max , -Δky max ≦Δky≦Δky max Where, Δkx max and Δky max The size of Δkx is determined by the spread angle of the optical image. In other words, Δkx max and Δky max The size depends on the optical image to be displayed.

[0246] Figure 28 It is a three-dimensional observation Figure 27 The diagram shows a three-dimensional representation of the inverted lattice space. Figure 28 This represents the Z-axis, which is orthogonal to both the Γ-X-axis and the Γ-Y-axis. This Z-axis is... Figure 1 The Z-axis shown is the same. For example... Figure 28As shown, in the case of an S-iPM laser oscillating at point Γ, the output has a two-dimensional extended optical image (beam pattern) LM that includes not only the 0th order light in the direction perpendicular to the plane (Z-axis direction), but also the +1 and -1 order light in the direction inclined relative to the Z-axis direction.

[0247] Next, the S-iPM laser oscillating at point M will be described. The conditions for oscillation at point M are the same as those for the PCSEL described above. Figure 29 This is a top view showing the inverted lattice space of the phase modulation layer of an S-iPM laser oscillating at point M. The fundamental inverted lattice vector B1 is the same as that of the PCSEL oscillating at point M (see reference). Figure 26 However, the in-plane wavenumber vectors K6 to K9 each have wavenumber extensions SP based on the rotation angle distribution φ(x,y). The shape and size of these wavenumber extensions SP are the same as in the case of the Γ-point oscillation described above. In the S-iPM laser, in the case of M-point oscillation, the magnitudes of the in-plane wavenumber vectors K6 to K9 (i.e., the magnitudes of the standing waves in the in-plane direction) are smaller than the magnitude of the basic reciprocal lattice vector B1 (due to diffraction, the wavenumber in the in-plane direction cannot be 0, and diffraction in the direction perpendicular to the plane (Z-axis direction) is not generated). Therefore, neither the 0th order light in the direction perpendicular to the plane (Z-axis direction) nor the +1 and -1 order light in directions tilted relative to the Z-axis direction are output.

[0248] Here, in this ninth variation, in the S-iPM laser oscillating at point M, by performing the following processing on the phase modulation layer 12B, a portion of the +1 and -1 orders of light are output without outputting the 0th order light. Specifically, as... Figure 30 As shown, by adding a diffraction vector V with a certain magnitude and direction to the in-plane wavenumber vectors K6 to K9, the magnitude of at least one of the in-plane wavenumber vectors K6 to K9 (K8 in the figure) is set to be less than 2π / λ. In other words, at least one of the in-plane wavenumber vectors K6 to K9 (K8) after adding the diffraction vector V converges within a circular region (ray) LL of radius 2π / λ. Figure 30 The dashed lines represent the in-plane wavenumber vectors K6 to K9 before the addition calculation of the diffraction vector V, while the solid lines represent the in-plane wavenumber vectors K6 to K9 after the addition calculation of the diffraction vector V. The ray LL corresponds to the total internal reflection condition and converges to the wavenumber vector of magnitude within the ray LL, having a component perpendicular to the plane (Z-axis direction). In one example, the direction of the diffraction vector V is along the Γ-M1 axis or the Γ-M2 axis, and its magnitude ranges from 2π / (2... 1 / 2 )a-π / λ to 2π / (2 1 / 2 Within the range of a+π / λ (as an example, 2π / (2 1 / 2 a).

[0249] The magnitude and direction of the diffraction vector V, which is used to converge at least one of the in-plane wavenumber vectors K6 to K9 into the ray LL, are studied. Equations (11) to (14) below represent the in-plane wavenumber vectors K6 to K9 before adding the diffraction vector V.

[0250] [Number 11]

[0251]

[0252] [Number 12]

[0253]

[0254] [Number 13]

[0255]

[0256] [Number 14]

[0257]

[0258] Among them, the expansions Δkx and Δky of the wavenumber vector satisfy the following equations (15) and (16), respectively, and the maximum value of the expansion of the wavenumber vector in the x-axis direction is Δkx. max The maximum value of the expansion in the y-axis direction Δky max The angle extension of light that forms the optical image in the design is specified.

[0259] [Number 15]

[0260] -Δkx max ≤Δkx≤Δkx max …(15)

[0261] [Number 16]

[0262] -Δky max ≤Δky≤Δky max …(16)

[0263] Here, when the diffraction vector V is expressed as in equation (17) below, the in-plane wavenumber vectors K6 to K9 after adding the diffraction vector V become equations (18) to (21) below.

[0264] [Number 17]

[0265] V = (Vx, Vy) …(17)

[0266] [Number 18]

[0267]

[0268] [Number 19]

[0269]

[0270] [Number 20]

[0271]

[0272] [Number 21]

[0273]

[0274] In the above equations (18) to (21), considering that any one of the wave number vectors K6 to K9 converges within the ray LL, the following relationship (22) holds.

[0275] [Number 22]

[0276]

[0277] That is, by adding the diffraction vector V that satisfies the above equation (22), any one of the wavenumber vectors K6 to K9 converges into the light LL, and outputs a portion of the +1 order light and the -1 order light.

[0278] The reason for making the size (radius) of the ray LL 2π / λ is as follows. Figure 31 This diagram schematically illustrates the peripheral structure of a light ray LL, showing the boundary between the device and air as viewed from a direction perpendicular to the Z-axis. The magnitude of the wavenumber vector of light in a vacuum is 2π / λ, but in... Figure 31 When light propagates through the device's medium, the magnitude of the wavenumber vector Ka within the medium with refractive index n becomes 2πn / λ. At this point, to ensure light propagates at the boundary between the device and air, the wavenumber component parallel to the boundary must be continuous (wavenumber conservation law). Figure 31 When the wavenumber vector Ka forms an angle θ with the Z-axis, the length of the wavenumber vector projected onto the plane (i.e., the in-plane wavenumber vector) Kb is (2πn / λ)sinθ. On the other hand, generally, based on the refractive index n > 1, the wavenumber conservation law does not hold when the in-plane wavenumber vector Kb within the medium is at an angle greater than 2π / λ. In this case, total internal reflection cannot be achieved, and the light cannot be extracted to the air side. The magnitude of the wavenumber vector corresponding to this total internal reflection condition is called the magnitude of the ray LL, which is 2π / λ.

[0279] As an example of a specific method of adding the diffraction vector V to the in-plane wavenumber vectors K6 to K9, it is possible to consider superimposing a rotation angle distribution φ1(x,y) (first phase distribution), which is the phase distribution used to form the desired optical image, with a rotation angle distribution φ2(x,y) (second phase distribution) that is unrelated to the optical image. In this case, the rotation angle distribution φ(x,y) of the phase modulation layer 12B is represented as:

[0280] φ(x,y)=φ1(x,y)+φ2(x,y).

[0281] φ1(x,y) corresponds to the phase of the complex amplitude when performing an inverse Fourier transform on the optical image as described above. Furthermore, φ2(x,y) is the rotation angle distribution used to add the diffraction vector V that satisfies equation (22) above. Figure 32 This is a diagram that conceptually represents an example of the rotation angle distribution φ2(x,y). For example... Figure 32 As shown, in this example, the first phase value φA and the second phase value φB, which are different from the first phase value φA, are arranged in a checkerboard pattern. That is, the second phase value φB, which is different from the first phase value φA, is arranged alternately along two orthogonal directions. In one example, the first phase value φA is 0 (rad) and the second phase value φB is π (rad). That is, the first phase value φA and the second phase value φB change by π each time. Through such an arrangement of phase values, a diffraction vector V along the Γ-M1 axis or the Γ-M2 axis can be appropriately realized. When the first phase value φA and the second phase value φB are arranged in a checkerboard pattern as described above, such as V = (±π / a, ±π / a), the diffraction vector V interacts with the first phase value φA and the second phase value φB in a checkerboard pattern each time. Figure 29 The wavenumber vectors K6 to K9 cancel each other out. Furthermore, by changing the arrangement direction of the first and second phase values ​​φA and φB from 45°, the orientation of the diffraction vector V can be adjusted to any orientation.

[0282] In this ninth variation, if the structure includes the UC layer 11 and the phase modulation layer 12B, the material system, film thickness, and layer structure can be varied. Here, for a so-called square lattice photonic crystal laser where the perturbation from the hypothetical square lattice is zero, the proportionality law holds. That is, when the wavelength is a constant α times, the same standing wave state can be obtained by making the entire square lattice structure α times larger. Similarly, in this variation, the structure of the phase modulation layer 12B can be determined using the proportionality law corresponding to the wavelength.

[0283] The effects obtained by the phase modulation layer 12B in the ninth modification example, as described above, will now be explained. In this ninth modification example, the lattice spacing a of the hypothetical square lattice and the emission wavelength λ of the UC layer 11 satisfy the condition for M-point oscillation. Normally, light propagating within the phase modulation layer 12B in the standing wave state of M-point oscillation will undergo total internal reflection, and the outputs of both the signal light (+1 and -1 orders) and the 0th order light will be suppressed. However, in the ninth modification example, at least one of the in-plane wavenumber vectors K6 to K9 formed in the inverted lattice space of the phase modulation layer 12B, i.e., the in-plane wavenumber vectors K6 to K9 that each contain a wavenumber extension Δk based on the rotation angle distribution φ(x,y), is smaller than 2π / λ (ray LL). In an S-iPM laser, such in-plane wavenumber vectors K6 to K9 can be adjusted, for example, by adjusting the rotation angle distribution φ(x,y). Therefore, when the magnitude of at least one in-plane wavenumber vector is smaller than 2π / λ, this in-plane wavenumber vector has a component in the Z-axis direction. As a result, a portion of the signal light is output from the phase modulation layer 12B. However, the zero-order light is still confined in-plane in the direction consistent with any of the four wavenumber vectors (±π / a, ±π / a) forming the standing wave at point M, and therefore is not output from the phase modulation layer 12B into the light beam. That is, according to this ninth modification, it is possible to remove the zero-order light contained in the output of the S-iPM laser from the light beam, and only the signal light is output into the light beam.

[0284] Furthermore, as in the 9th variation, the rotation angle distribution φ(x,y) can also be an overlap of the rotation angle distribution φ1(x,y) corresponding to the optical image and the rotation angle distribution φ2(x,y) unrelated to the optical image. In this case, the rotation angle distribution φ2(x,y) can also be a rotation angle distribution used to add a diffraction vector V with a certain magnitude and direction to the in-plane wavenumber vectors K6 to K9 in the four directions based on the rotation angle distribution φ1(x,y) in the inverted lattice space of the phase modulation layer 12B. Thus, the result of adding the diffraction vector V to the in-plane wavenumber vectors K6 to K9 in the four directions is that the magnitude of at least one of the in-plane wavenumber vectors K6 to K9 in the four directions can be smaller than 2π / λ. Therefore, it is easy to realize a structure in inverted lattice space containing at least one of the in-plane wavenumber vectors K6 to K9 in four directions based on the wavenumber extensions Δkx and Δky of the rotation angle distribution φ(x,y), which is smaller than 2π / λ (ray).

[0285] Furthermore, as in this ninth variation, the rotation angle distribution φ2(x,y) can also be a pattern in which phase values ​​φA and φB, which have different values, are arranged in a checkerboard pattern. With such a rotation angle distribution φ2(x,y), the diffraction vector V described above can be easily realized.

[0286] Figure 33 This is a diagram illustrating an example of the rotation angle distribution φ(x,y) of the phase modulation layer 12B. Furthermore, Figure 34 It is Figure 33 The diagram shown is a magnified representation of part S. Figure 33 and Figure 34 In this context, the magnitude of the rotation angle is represented by the color density; the denser the area, the larger the rotation angle (i.e., the larger the phase angle). (See reference...) Figure 34 It can be seen that the phase values ​​that are different from each other are arranged in a checkerboard pattern and are overlapped. Figure 35 Indicates from having Figure 33 The optical element outputs a beam pattern (optical image) with a rotation angle distribution φ(x,y). Furthermore, Figure 36 yes Figure 21 A schematic diagram of the beam pattern shown. Figure 35 and Figure 36 The center corresponds to the Z-axis. According to Figure 35 and Figure 36 It is evident that the optical element outputs: +1 order light, including the first optical image portion LM1, output in the first direction tilted relative to the Z-axis; and -1 order light, including the second optical image portion LM2, which is rotationally symmetrical about the Z-axis and the first direction, output in the second direction symmetrical about the Z-axis and the first optical image portion LM1, but does not output 0 order light traveling on the Z-axis.

[0287] In this ninth variation, a pattern containing and symmetrical about the Z-axis can also be output. Since there is no zero-order light, there is no intensity unevenness in the pattern along the Z-axis. Examples of such beam patterns include 5×5 multi-point, mesh, and 1D patterns. Schematic diagrams of these beam patterns are shown below. Figure 37 (a) Figure 38 (a) and Figure 39 As shown in (a), the phase distribution of the beam pattern is as follows: Figure 37 (b) Figure 38 (b) and Figure 39 As shown in (b). By outputting such a beam pattern in the visible area, it can be applied, for example, to display applications.

[0288] (Example 10)

[0289] In this tenth variation, in the phase modulation layer 12C of the third embodiment described above, similar to the ninth variation, the lattice spacing a of the hypothetical square lattice and the emission wavelength λ of the UC layer 11 satisfy the condition for M-point oscillation. Furthermore, when considering the inverted lattice space in the phase modulation layer 12C, at least one of the in-plane wavenumber vectors, which respectively contain wavenumber spreads based on the distance r(x,y), has a magnitude less than 2π / λ (ray).

[0290] In a detailed explanation, in the 10th variation, by performing the following operation on the phase modulation layer 12C in the S-iPM laser oscillating at the M point, a portion of the +1 and -1 orders of light are output without outputting the 0th order light into the beam. Specifically, as... Figure 30 As shown, by adding a diffraction vector V with a certain magnitude and direction to the in-plane wavenumber vectors K6 to K9, the magnitude of at least one of the in-plane wavenumber vectors K6 to K9 is set to be less than 2π / λ. In other words, after adding the diffraction vector V, at least one of the in-plane wavenumber vectors K6 to K9 converges within a circular region (ray) LL with a radius of 2π / λ. That is, by adding the diffraction vector V that satisfies the above equation (22), any one of the in-plane wavenumber vectors K6 to K9 converges within the ray LL, outputting a portion of the +1 order light and the -1 order light.

[0291] In the 10th variation, the lattice spacing 'a' of the hypothetical square lattice and the emission wavelength 'λ' of the UC layer 11 satisfy the condition for M-point oscillation. Furthermore, in the reciprocal lattice space of the phase modulation layer 12C, a plane wave forming a standing wave is phase-modulated by a distribution at distance r(x,y). At least one of the in-plane wavenumber vectors K6 to K9, each containing a wavenumber extension Δk based on the optical image's angle extension, has a magnitude less than 2π / λ (light ray). Alternatively, by adding the diffraction vector V to the in-plane wavenumber vectors K6 to K9 from the four in-plane wavenumber vectors after removing the wavenumber extension Δk, the magnitude of at least one in-plane wavenumber vector becomes less than the value {(2π / λ)-Δk} obtained by subtracting the wavenumber extension Δk from 2π / λ. Therefore, it is possible to remove the zero-order light contained in the output of the S-iPM laser from the light ray, outputting only the signal light.

[0292] The optical and light-emitting devices of the present invention are not limited to the embodiments described above and can be modified in various other ways. For example, in the above description, excitation light sources 20A and 20C are described as PCSELs, but excitation light sources 20A and 20C can also be S-iPMSELs.

[0293] (Fourth implementation)

[0294] In the first to third embodiments and the first to tenth variations described above, optical devices 10A to 10E and light-emitting devices 1A to 1H and 1J with electrodes disposed on the back side of excitation light sources 20A to 20C and having a UC layer (upconversion layer) were disclosed. However, in the manufacture of these light-emitting devices, high-precision electrode forming technology is required when forming electrodes on the back side of the excitation light sources 20A to 20C, which serve as the light source. That is, in optical devices where electrodes are disposed on the back side of the excitation light source, a high degree of flatness and parallelism is required for the surfaces of the two light confinement layers and the UC layer and PC layer (or phase modulation layer) sandwiched between these two light confinement layers in order not to disturb the in-plane waveguide mode. Especially in the embodiments and variations described above, ensuring the aforementioned flatness and parallelism is important in order to form the light confinement layer with an opening provided on the electrodes on the back side of the excitation light source. In this fourth embodiment, in order to alleviate such stringent manufacturing conditions, the device structure has an optical device disposed on the flat back side of the excitation light source by changing the electrode configuration of the excitation light source.

[0295] On the other hand, in optical devices 10A-10E and 10A1 that serve as resonators, a first light-reflecting layer and a second light-reflecting layer, both composed of dielectric multilayer films, are used as light confinement layers. However, in the fourth embodiment, instead of at least the second light-reflecting layer among these first and second light-reflecting layers, a light confinement layer is used, which is made of a single material having a substantially uniform refractive index distribution along the stacking direction of the optical device and a refractive index lower than that of the UC layer. In this case, the manufacturing process can be simplified compared to dielectric multilayer films, especially for the single-layer structure of the light confinement layer that replaces the second light-reflecting layer, the layer thickness can be suppressed to be thinner. By thinning the light confinement layer, it is expected that the formation of higher-order modes along the stacking direction of the optical device can be suppressed. Moreover, when a single-layer structure of the light confinement layer is used instead of the second light-reflecting layer, the PC layer (photonic crystal layer) adjacent to the UC layer can be buried inside or on the surface of the light confinement layer (ressonator structure that is prone to oscillation).

[0296] Furthermore, in the optical device of the fourth embodiment, the PC layer (or phase modulation layer) is disposed on the output side compared to the UC layer. By adopting this structure, even when the UC layer contains a scattering material, the influence on the formation of the resonant mode is small, the increase of the oscillation threshold can be prevented, and the noise mixed into the output wavefront (beam pattern) can be minimized.

[0297] Figure 40This is a schematic diagram used to illustrate the structure of the light-emitting device of the fourth embodiment by comparing it with the light-emitting device of the first embodiment. Optical devices 100A and 100B, indicated by arrow (a) and (b), can be replaced by the aforementioned optical devices 10A-10E and 10A1. Furthermore, the excitation light source 200A, indicated by arrow (c), can also be replaced by the aforementioned excitation light sources 20A-20C. A structure in which multiple excitation light sources 200A (each excitation light source 200A includes a photonic crystal surface-emitting laser) are applied to one optical device 100A-100F can also be used, which is the same as in the aforementioned embodiments and variations. Furthermore, in the light-emitting device of the fourth embodiment, as in the aforementioned embodiments and variations, any one of the dichroic mirror 16, diffractive optical element 17, and spatial light modulator 40 can be arranged on the opposite side of the UC layer 11 relative to the second light confinement layer 140. In all the figures showing the structure of the light-emitting device of the fourth embodiment, the dichroic mirror 16, the diffractive optical element 17, and the spatial light modulator 40 are omitted.

[0298] exist Figure 40 In the example, the optical device 100A indicated by arrow (a) includes: a substrate 15 (a light-transmitting quartz plate); a second light-confining layer 430 disposed on one side of the substrate 15; a PC layer 120 (which may also be a phase modulation layer) disposed on the second light-confining layer 140; a UC layer 11 disposed on the PC layer 120; and a first light-confining layer 130 disposed on the UC layer 11. On the other side of the substrate 15, any one of the dichroic mirror 16, the diffractive optical element 17, and the spatial light modulator 40 can be disposed similarly to the first to third embodiments and the first to tenth variations described above. The PC layer 120 is composed of a base layer 120a and a plurality of PC layers 120 having a refractive index different from that of the base layer 120a, and the second light-confining layer 140 adopts a single-layer structure with a substantially uniform refractive index distribution along the thickness direction. In the optical device 100A, the first light confinement layer 130 can be a dielectric multilayer film or a single-layer structure.

[0299] exist Figure 40In the example, the optical device 100B indicated by arrow (b) has: a light-transmitting substrate 15; a second light-confining layer 140 disposed on one side of the substrate 15; a PC layer 120 (which may also be a phase modulation layer) disposed inside or on the surface of the second light-confining layer 140; a UC layer 11 disposed on the second light-confining layer 140 containing the PC layer 120; and a first light-confining layer 130 disposed on the UC layer 11. On the other side of the substrate 15, any one of the dichroic mirror 16, the diffractive optical element 17, and the spatial light modulator 40 may be disposed in the same manner as the optical device 100A. The PC layer 120 embedded in the second light-confining layer 140 is composed of a base layer 120a and a plurality of PC layers 120 having a refractive index different from that of the base layer 120a, and the second light-confining layer 140 is composed of a single material having a substantially uniform refractive index distribution along the thickness direction (having a single-layer structure). In this optical device 100B, the first light confinement layer 130 can be a dielectric multilayer film or a single-layer structure.

[0300] exist Figure 40 In the example, the excitation light source 200A (including a semiconductor stack that functions as a photonic crystal surface-emitting laser) indicated by arrow (c) includes: a semiconductor substrate 21; a first capping layer 24 (serving as a light confinement layer) disposed on the main surface 21a of the semiconductor substrate 21; an active layer 22 disposed on the first capping layer 24; a PC layer 23 disposed on the active layer 22; a second capping layer 25 (serving as a light confinement layer) disposed on the PC layer 23; a contact layer 26 disposed on the second capping layer 25; a second electrode 28 (p electrode) disposed on the semiconductor stack including the active layer 22 and the PC layer 23; and a first electrode 27 (n electrode) disposed on the main surface 21a of the semiconductor substrate 21. Wherein, in Figure 40 In the excitation light source 200A shown, a first light confinement layer 130, constituting part of the optical device 100A or optical device 100B, is disclosed on the back side 21b of the semiconductor substrate 21. This is because the first light confinement layer 130 is formed on the back side 21b of the semiconductor substrate 21 in the final stage of the manufacturing process described below for the excitation light source 200A. Furthermore, in Figure 40 In the excitation light source 200A shown, the first light confinement layer 130 disposed on the back side 21b of the semiconductor substrate 21 is shown as a dielectric multilayer film, but it can also be a single-layer structure with a substantially uniform refractive index distribution along the thickness direction, just like the second light confinement layer 140 described above.

[0301] In particular, in the excitation light source 200A of the fourth embodiment, both the first electrode 27 and the second electrode 28 are disposed on the main surface 21a side of the semiconductor substrate 21. Therefore, the area of ​​the PC layer 23 viewed from the stacking direction of the semiconductor stack (photonic crystal surface-emitting laser) is smaller than the area of ​​the UC layer 11 viewed from the stacking direction of the aforementioned optical devices 100A and 100B, and more specifically, smaller than the area of ​​the main surface 21a of the semiconductor substrate 21 (the first electrode 27 is disposed on the area of ​​the main surface 21a of the semiconductor substrate 21 that is not covered by the semiconductor stack). With such an electrode configuration, since both the first electrode and the second electrode are disposed on the main surface 21a side of the semiconductor substrate 21, the mounting operation of the light-emitting device of the present invention on the substrate becomes easier, and the effective area can be increased.

[0302] The light-emitting device of the fourth embodiment, having the structure described above, can be manufactured using either a unit assembly type (first manufacturing method) or an upconversion material injection type (second manufacturing method). Therefore, firstly, using... Figures 41-44 The manufacturing method for unit assembly type will be explained in detail. Further explanation follows. Figure 41 This diagram illustrates the manufacturing process of the excitation light source 200A, which serves as the light-emitting part, in the manufacturing process (first manufacturing method) of the unit assembly type of the light-emitting device according to the fourth embodiment. Figure 42 (a) and Figure 42 (b) is a diagram illustrating the installation process of the excitation light source onto the base in the first manufacturing method. Figure 43 (a) and Figure 43 (b) is a diagram illustrating the manufacturing process of the optical device (resonator section) in the first manufacturing method. Figure 43 (c) is a diagram illustrating the mounting process of the optical device onto the base on which the excitation light source has been mounted in the first manufacturing method. Figure 44 (a) and Figure 44 (b) shows the top view and cross-sectional view of the manufactured light-emitting device.

[0303] The manufacturing process of the 200A excitation light source, such as... Figure 41 The process is shown in the order of arrows (a), (b), and (c). First, on the main surface 21a of the semiconductor substrate 21 with a width of 800 μm or more, a first capping layer 24, an active layer 22, a PC layer 23 composed of a base layer 23a and multiple regions 23b with different refractive indices, a second capping layer 25, and a contact layer 26 are sequentially disposed. The width of the diffraction lattice region of the PC layer 23 can be approximately 400 μm. The fabrication of this semiconductor stack disposed on the main surface 21a of the semiconductor substrate 21 is the same as that of the excitation light sources 20A-20C in the first to third embodiments and the first to tenth variations described above.

[0304] Next, by etching a portion of the semiconductor laminate disposed on the main surface 21a of the semiconductor substrate 21, a portion of the main surface 21a of the semiconductor substrate 21 is exposed, thereby obtaining... Figure 41 The cross-sectional structure is shown by arrow (a). At this time, the width of the remaining semiconductor stack is about 500 μm, and the exposed area becomes the setting area of ​​the first electrode 27. When the setting area of ​​the first electrode 27 is secured by etching, an insulating layer 290 such as SiN is coated on the semiconductor stack remaining on the main surface 21a of the semiconductor substrate 21 and the exposed area. Next, after a portion of the insulating layer 290 located in the setting areas of the first electrode 27 and the second electrode 28 is removed, Au plating is performed, and the first electrode 27 and the second electrode 28 are patterned. After Au plating, the main surface 21a can also be planarized by CMP (Chemical Mechanical Planarization) if necessary. Therefore, the first electrode 27 provided on the main surface 21a and the second electrode 28 provided on the contact layer 26 side of the semiconductor stack are insulated from each other by the insulating layer 290. After this process, a Figure 41 The cross-sectional structure is shown by arrow (b).

[0305] As described above, since the first electrode 27 and the second electrode 28 are disposed on the main surface 21a side of the semiconductor substrate 21, a SiN monolayer or dielectric multilayer film can be directly formed on the back surface 21b of the semiconductor substrate 21 as the first light confinement layer 130. Therefore, it is possible to obtain... Figure 41 The cross-sectional structure is shown by arrow (c). The thickness ratios of the various parts of the excitation light source 200A (illustrated excitation light source 200A) shown by arrow (c) differ from the thickness ratios of the various parts in an actual manufactured device, but overall, the thickness of the excitation light source 200A is at most approximately 100 μm to 150 μm. Furthermore, on the main surface 21a of the semiconductor substrate 21, the first electrode 27 has a shape that surrounds the second electrode 28.

[0306] When passing Figure 41 When the manufacturing process shown yields an excitation light source of 200A, as... Figure 42 As shown in (a), the excitation light source 200A is flip-mounted onto the main surface 500a of a 2mm × 2.5mm base 500. An n-electrode pad 520, which should be electrically connected to the first electrode 27, and a p-electrode pad 510, which should be electrically connected to the second electrode 28, are pre-printed on the main surface 500a of the prepared base 500. Furthermore, when the excitation light source 200A is fixed to the base 500, spacers 550a to 550d made of insulating material are also fixed to the main surface 500a of the base 500 to surround the excitation light source 200A.

[0307] On the other hand, in the case of manufacturing optical device 100A, such as Figure 43 As shown in (a), firstly, a light-transmitting substrate 15 is prepared. Since only the flat central portion of the laminated portion is used in the prepared substrate 15, a sufficiently large quartz plate is used. On one surface of this substrate 15, a second light-containing layer 140 having a single-layer structure composed of SiN, TiO2, etc., is first formed. Then, a PC layer 120 composed of a base layer and multiple regions with different refractive indices is formed on the second light-containing layer 140. After applying an ultraviolet-curable resin (UC layer 11) with upconversion material as the main raw material to the PC layer 120 by spin coating, the UC layer 11 is UV-cured. In the manufacturing of this UC layer 11, flatness and parallelism are very important. Especially when the ultraviolet-curable resin (containing upconversion material as the main raw material) is applied by spin coating, flatness at the ends cannot be obtained. Therefore, as... Figure 43 As shown in (b), since the central portion (the flat area of ​​the laminate) on the substrate 15 is used, by cutting the laminate including the substrate 15 with a width of 2 mm, an optical device 100A of about 2 mm × 2 mm can be obtained (the first light confinement layer 130 is formed on the side of the excitation light source 200A).

[0308] The optical device 100A obtained as described above, such as Figure 43 As shown in (c), the UC layer 11 is in direct contact with the first light confinement layer 130 on the excitation light source 200A side flipped on the base 500, and is mounted on the base 500 with spacers 550a to 550d in between.

[0309] in, Figure 44 (a) is a top view of a light-emitting device manufactured by the first manufacturing method (unit assembly type) as described above, which involves individually manufacturing and assembling the units (excitation light source 200A and optical device 100A) constituting the light-emitting device of the fourth embodiment. Figure 44 (b) is along Figure 44 (a) is a cross-sectional view of the light-emitting device shown by arrow II. Figure 44 (b) does not include the dichroic mirror or other components shown in the diagram.

[0310] Figure 45 (a) is a cross-sectional view of a light-emitting device having a light-confining layer of the first structure, manufactured by the unit assembly type manufacturing method (first manufacturing method) described above. Fourth Embodiment Figure 45 (a) The light-emitting device includes an excitation light source 200A and an optical device 100C that abuts against the excitation light source 200A through a first light confinement layer 130.

[0311] exist Figure 45In the example shown in (a), the excitation light source 200A can be replaced with the excitation light sources 20A-20C of the first to third embodiments and the first to tenth modifications described above, and the basic structure has Figure 40 The cross-sectional structure is shown by arrow (c). That is, the excitation light source 200A includes: a semiconductor substrate 21 made of GaAs; a first capping layer 24 disposed on the main surface 21a of the semiconductor substrate 21; an active layer 22 disposed on the first capping layer 24; a PC layer 23 (which may also be a phase modulation layer) disposed on the active layer 22; a second capping layer 25 disposed on the PC layer 23; a contact layer 26 disposed on the second capping layer 25; a second electrode 28 disposed on the contact layer 26; a first electrode 27 disposed on the area of ​​the main surface 21a of the semiconductor substrate 21 that is not covered by the semiconductor laminate containing the active layer 22 and the PC layer 23; and an insulating layer 290 made of SiN or the like covering the main surface 21a and the surface of the semiconductor laminate, excluding the first electrode 27 and the second electrode 28. The PC layer 23 is composed of a base layer 23a made of GaAs and multiple regions 23b with different refractive indices defined by vacancies disposed on the base layer 23a.

[0312] On the other hand, the optical device 100C is mounted on the excitation light source 200A (on the back side 21b of the semiconductor substrate 21) via a first light confinement layer 130 composed of a dielectric multilayer film (or a single-layer structure composed of SiN, TiO2, etc.). The optical device 100C includes: a light-transmitting substrate 15; a second light confinement layer 140 having a first structure disposed on one side of the substrate 15; a PC layer 120 (or a phase modulation layer) embedded in the interior or surface region of the second light confinement layer 140; a UC layer 11 sandwiched between the PC layer 120 and the first light confinement layer 130; and the first light confinement layer 130.

[0313] In this optical device 100C, the second light confinement layer 140 has a base 141 and a capping layer 142, each composed of a monolayer structure of SiN or TiO2. A PC layer 120 is located between the base 141 and the capping layer 142, and includes a base layer 120a and multiple regions 120b with different refractive indices. The base layer 120a also has a monolayer structure composed of SiN or TiO2. The multiple regions of the PC layer 120 with different refractive indices are voids. The capping layer 142 also has a monolayer structure composed of SiN or TiO2. Here, when the base 141 and the base layer 120a of the PC layer 120 are composed of different materials (for example, the base 141 is composed of SiN and the base layer 120a is composed of TiO2), the structure of this optical device 100C is substantially similar to... Figure 40The structure of the optical device 100A, indicated by arrow (a) in the diagram, is consistent with that of the optical device 100A. On the other hand, when the base 141, the base layer 120a of the PC layer 120, and the capping layer 142 are made of the same material (e.g., each made of SiN), the structure of the optical device 100C is substantially the same as that of the optical device 100C. Figure 40 The structure of the optical device 100B shown by arrow (b) is consistent with that of the PC layer 120, which is embedded inside the second light confinement layer 140 having a single-layer structure.

[0314] The light-emitting device (fourth embodiment with the first structure in the second light confinement layer 140) obtained by the unit assembly type manufacturing method described above (first manufacturing method) does not apply unnecessary heat to the UC layer 11 provided on the substrate 15. Furthermore, the multiple regions 120b (gaps) with different refractive indices provided on the PC layer 120 are not filled with upconversion material. Moreover, before mounting the optical device 100C to the excitation light source 200A, the initial optical characteristics of the photonic crystal surface-emitting laser can be measured.

[0315] Figure 45 (b) is a cross-sectional view of a light-emitting device having a light-confining layer of the second structure manufactured by the unit assembly type manufacturing method (first manufacturing method) described above. Fourth Embodiment Figure 45 (b) The light-emitting device includes: an excitation light source 200A; and an optical device 100D that abuts against the excitation light source 200A via a first light confinement layer 130. Furthermore, Figure 45 (b) The light-emitting device, except for the point where the optical device 100D has the PC layer 120 of the second structure, has the same... Figure 45 (a) has the same structure as the light-emitting device.

[0316] That is, the optical device 100D is mounted on the excitation light source 200A (on the back side 21b of the semiconductor substrate 21) through a first light confinement layer 130 composed of a dielectric multilayer film (or it may have a single-layer structure composed of SiN, TiO2, etc.). The optical device 100D includes: a light-transmitting substrate 15; a second light confinement layer 140 having a second structure disposed on one side of the substrate 15; a PC layer 120 (or a phase modulation layer) embedded in the surface region of the second light confinement layer 140; a UC layer 11 sandwiched between the PC layer 120 and the first light confinement layer 130; and the first light confinement layer 130.

[0317] In this optical device 100D, the second light confinement layer 140 has a base 141 with a monolayer structure made of SiN and a capping layer 142 with a monolayer structure made of TiO2. A PC layer 120 is located between the base 141 and the capping layer 142, and includes a base layer 120a and multiple regions 120b with different refractive indices. The base layer 120a also has a monolayer structure made of SiN and substantially constitutes part of the second light confinement layer 140. The multiple regions 120b with different refractive indices of the PC layer 120 are defined by multiple recesses provided in the base layer 120a constituting part of the second light confinement layer 140, and these recesses are filled with TiO2 material, the same material as the capping layer 142. Here, when the base 141 and the base layer 120a of the PC layer 120 are made of different materials (for example, the base 141 is made of SiN and the base layer 120a is made of TiO2), the structure of this optical device 100D is substantially the same as... Figure 40 The structure of the optical device 100A, indicated by arrow (a), is consistent with that of the optical device 100A. In this case, although the base layer 120a and the multiple regions 120b with different refractive indices are made of the same material, the refractive index of the base layer 120a is different from that of the multiple regions 120b. On the other hand, when the base layer 120a of the slab 141 and the PC layer 120 are made of the same material (e.g., both are made of SiN), the structure of the optical device 100D is substantially the same as that of the base layer 120A. Figure 40 The structure of the optical device 100B shown by arrow (b) is consistent with that of the PC layer 120, which is embedded in the surface region of the second light confinement layer 140 with a single-layer structure.

[0318] Through this Figure 45 The light-emitting device shown in (b) (the fourth embodiment where the second light-confining layer 140 has the second structure) can also obtain the same... Figure 45 The light-emitting device shown in (a) has the same effect.

[0319] Figure 46 (a) is a cross-sectional view of a light-emitting device having a third structure light-confining layer manufactured by the above-described unit assembly type manufacturing method (first manufacturing method). Fourth Embodiment Figure 46 (a) The light-emitting device includes an excitation light source 200A and an optical device 100E that abuts against the excitation light source 200A via a first light confinement layer 130. Furthermore, Figure 46 (a) The light-emitting device, except for the point where the optical device 100E has the third structure of the PC layer 120, has the same... Figure 45 (a) has the same structure as the light-emitting device.

[0320] That is, the optical device 100E is mounted on the excitation light source 200A (on the back side 21b of the semiconductor substrate 21) through a first light confinement layer 130 composed of a dielectric multilayer film (or it may have a single-layer structure composed of SiN, TiO2, etc.). The optical device 100E includes: a light-transmitting substrate 15; a second light confinement layer 140 having a third structure disposed on one side of the substrate 15; a PC layer 120 (or a phase modulation layer) embedded in the surface region of the second light confinement layer 140; a UC layer 11 sandwiched between the PC layer 120 and the first light confinement layer 130; and the first light confinement layer 130.

[0321] In this optical device 100E, the second light-confining layer 140 has a single-layer structure made of SiN, and multiple recesses are formed on its surface to define multiple regions 120b with different refractive indices of the PC layer 120. Therefore, the surface region of the second light-confining layer 140, where the multiple recesses are formed, becomes the base layer 120a of the PC layer 120. In this third-structure PC layer 120, the surface of the second light-confining layer 140 and the inner walls (including the bottom) of the multiple recesses are covered by a capping layer 120c made of TiO2. This optical device 100E, having this third-structure PC layer 120, is substantially similar to... Figure 40 The structure of the optical device 100B shown by arrow (b) is consistent with that of the PC layer 120, which is embedded in the surface region of the second light confinement layer 140 having a single-layer structure.

[0322] Through this Figure 46 The light-emitting device shown in (a) (the fourth embodiment where the second light-confining layer 140 has the second structure) can also obtain the same... Figure 45 The light-emitting device shown in (a) has the same effect.

[0323] Figure 46 (b) is a cross-sectional view of a light-emitting device having a light-confining layer of the fourth structure, manufactured by the unit assembly type manufacturing method (first manufacturing method) described above. Fourth Embodiment Figure 46 (b) The light-emitting device includes an excitation light source 200A and an optical device 100E that abuts against the excitation light source 200A via a first light confinement layer 130. Furthermore, Figure 46 (b) The light-emitting device, in addition to the point where the optical device 100E has the fourth structure of the PC layer 120, has the same... Figure 45 (a) has the same structure as the light-emitting device.

[0324] That is, the optical device 100F is mounted on the excitation light source 200A (on the back side 21b of the semiconductor substrate 21) through a first light confinement layer 130 composed of a dielectric multilayer film (or it may have a single-layer structure composed of SiN, TiO2, etc.). The optical device 100F includes: a light-transmitting substrate 15; a second light confinement layer 140 having a fourth structure disposed on one side of the substrate 15; a PC layer 120 (or a phase modulation layer) buried in the surface region of the second light confinement layer 140; a UC layer 11 sandwiched between the PC layer 120 and the first light confinement layer 130; and the first light confinement layer 130.

[0325] In this optical device 100F, the second light confinement layer 140 has a single-layer structure made of SiN, and multiple recesses are formed on its surface to define multiple regions 120b with different refractive indices of the PC layer 120. Therefore, the surface region of the second light confinement layer 140 with the multiple recesses forms the base layer 120a of the PC layer 120. In this fourth structure of the PC layer 120, the surface of the second light confinement layer 140 and the inner walls (including the bottom) of the multiple recesses are directly covered by the UC layer 11, resulting in a state where a portion of the UC layer 11 is filled in each of the multiple recesses. This optical device 100F with this fourth structure of the PC layer 120 is substantially similar to... Figure 40 The structure of the optical device 100B shown by arrow (b) is consistent with that of the PC layer 120, which is embedded in the surface region of the second light confinement layer 140 having a single-layer structure.

[0326] Through this Figure 46 The light-emitting device shown in (b) (the fourth embodiment where the second light confinement layer 140 has the second structure) can also obtain the same... Figure 45 The light-emitting device shown in (a) has the same effect.

[0327] Next, the resonator structure that is prone to oscillation was studied. Figure 47 This is a diagram used to illustrate the design guidelines for an optical device (including a resonator model of the second light confinement layer 140 and the PC layer 120). Figure 47The model 100G shown has a structure consisting of a PC layer 120 (which can also be considered a phase modulation layer), a second light confinement layer 140, and a UC layer 11 sandwiched between a pair of quartz plates 151 and 152. Quartz plates 151 and 152 both have a refractive index of 1.46 relative to light with a wavelength of 550 nm. The UC layer 11 has a refractive index of 1.5 relative to light with a wavelength of 550 nm. The second light confinement layer 140 is made of SiN and has a refractive index of 2.0 relative to light with a wavelength of 550 nm. The base layer 120a of the PC layer 120 is made of TiO2, and multiple regions 120b with different refractive indices are disposed in the vacancies of this base layer 120a. Furthermore, on the surface of the base layer 120a, the actual occupancy rate (hereinafter referred to as "FF (Filling Factor)") of the different refractive index regions 120b relative to the area that can be disposed of by one region 120b is 30%.

[0328] The first condition for designing a resonator structure that is prone to oscillation is to increase the proportion of light distributed in the UC layer 11. UC (Increase gain). To satisfy this first condition, it is necessary to design an appropriate layer structure, taking into account the property that light resides in layers with high refractive index and is far from layers with low refractive index. Furthermore, the second condition is to increase the light confinement intensity within the resonator section, that is, to increase the diffraction intensity κ of the PC layer 120. 2,0 Among them, the diffraction intensity κ m,n (cm -1 ) is represented by the following equation (23).

[0329] [Number 23]

[0330]

[0331] In equation (23) above, κ m,n This represents the diffraction intensity (equivalent to the coupling coefficient) of PC layer 120. The subscripts m and n indicate the number of reciprocal lattice vectors involved in the diffraction. For example, in the case of 180° diffraction in-plane, two reciprocal lattice vectors are involved, thus represented by (m,n) = (2,0) or (0,2). Furthermore, in the case of 90° diffraction from in-plane to the perpendicular direction, one reciprocal lattice vector is involved, thus represented by (m,n) = (1,0) or (0,1). k0 is the propagation constant of a plane wave in vacuum, λ is the wavelength of light, and β is the propagation constant. n eff It is the effective refractive index. Γ PC ε represents the proportion of light distributed in the PC layer 120 within the light (electric field distribution) along the stacking direction. in ε is the dielectric constant within the vacancies (various refractive index regions 120b) of PC layer 120. outIt is the dielectric constant outside the vacancy in PC layer 120. Furthermore, F... m,n It depends on the planar shape of the different refractive index regions 120b set in the PC layer 120. (In the case of 180° diffraction, (m,n) = (2,0) or (0,2), and in the case of 90° diffraction, (m,n) = (1,0) or (0,1)).

[0332] According to the above equation (23), in order to increase the light confinement intensity of the resonator (in order to increase the diffraction intensity κ in a way that does not distort the electric field distribution of light), 2,0 ), it is necessary to pay attention to increasing Γ separately. PC Increasing the refractive index difference between the interior and peripheral regions of PC layer 120, and increasing the Fourier coefficient F of the planar shape of the different refractive index regions 120b (vacancies) disposed in PC layer 120. 2,0 Designing an appropriate layer structure is crucial. When considering light moving away from layers with low refractive index, it might be better to embed other materials rather than filling the interiors of different refractive index regions 120b with low-refractive-index air.

[0333] The results of the above research indicate that, specifically, the refractive index of the PC layer 120 is preferably set to be higher than that of the surrounding region. Furthermore, it is understood that the difference in dielectric constant (ε) between the interior and surrounding regions of the PC layer 120... in -ε out The preferred method is to embed TiO2 regions 120b with different refractive indices into the holes of the SiN base layer 120a, forming an embedded PC layer structure. Therefore, to further study the detailed conditions, a more advanced method is used. Figure 48 , Figure 49 (a)~ Figure 49 (e) Figure 50 (a)~ Figure 50 (f) Figure 51 and Figure 52 (a)~ Figure 52 (e) Conduct research.

[0334] Figure 48 It is about having Figure 47 The cross-sectional structure of the optical device is shown in the figure. Various aperture shapes in the PC layer are represented by curves showing the relationship between Fourier coefficients and FF values. The prepared aperture shapes (planar shapes set in different refractive index regions 120b of the base layer 120a) are circles (pattern 1), squares (pattern 2), equilateral triangles (pattern 3), and isosceles right triangles (pattern 4).

[0335] Figure 48 The patterns 1-4 above represent Fourier coefficients F. 2,0 (180° diffraction) and F 1,0The relationship between the magnitude of (90° diffraction) and the FF value. These graphs show that even a slight reduction in aperture shape due to manufacturing tolerances will still be effective due to the Fourier coefficient F. 2,0 Since the refractive index is not close to 0, the planar shape of different refractive index regions 120b is preferably an isosceles right triangle with an FF30% refractive index. Subsequent calculations will primarily focus on the case where the planar shape of different refractive index regions 120b is an isosceles right triangle with an FF30% refractive index.

[0336] Figure 49 (a)~ Figure 49 (e) is a diagram illustrating the specific structural conditions of the resonator section structure that is prone to oscillation, based on the research results described above. That is, Figure 49 (a) indicates that the diffraction intensity κ can be increased. 2,0 An example of the cross-sectional structure of an optical device (including a resonator section model of the second light confinement layer 140 and the PC layer 120). Figure 49 (b) indicates that the distribution ratio can be increased. UC An example of the cross-sectional structure of an optical device (including a resonator model of the second light confinement layer 140 and the PC layer 120) (the distribution ratio of light present in UC layer 11). Figure 49 (c) is about Figure 49 (a) and Figure 49 (b) shows the cross-sectional structure of the optical device, representing the diffraction intensity κ. 2,0 With distribution ratio Γ UC The calculation results are presented in a table. Furthermore... Figure 49 (d) and Figure 49 (e) is a diagram used to illustrate the hole shape applied to the calculation.

[0337] Figure 49 (a) A cross-sectional structure of model 100H showing a structure (structure I) with increased diffraction intensity. Model 100H includes: a quartz plate 151; a PC layer 120 (or a phase modulation layer) with a thickness of 200 nm disposed on the quartz plate 151; a second light confinement layer 140 with a thickness of 200 nm disposed on the PC layer 120; and a UC layer 11 with a thickness of 2 μm disposed on the second light confinement layer 140. The quartz plate 151 has a refractive index of 1.46 relative to light with a wavelength of 550 nm. The UC layer 11 has a refractive index of 1.5 relative to light with a wavelength of 550 nm. The second light confinement layer 140 is made of SiN and has a refractive index of 2.0 relative to light with a wavelength of 550 nm. The base layer 120a of the PC layer 120 is made of TiO2, and multiple regions 120b with different refractive indices are vacancies disposed in the base layer 120a. Furthermore, the planar shape of the prepared regions 120b with different refractive indices is... Figure 49 (d) shows pattern 1 (circle) with FF = 10% and Figure 49(e) shows pattern 4 (isosceles right triangle) with FF = 30%.

[0338] on the other hand, Figure 49 (b) indicates that it has the ability to increase the distribution ratio of light present in UC layer 11 (Γ) UC The cross-sectional structure of model 100I (structure II) is described below. Model 100I comprises the following components: a quartz plate 151; a 100 nm thick PC layer 120 (which may also be a phase modulation layer) disposed on the quartz plate 151; a 100 nm thick second light confinement layer 140 disposed on the PC layer 120; and a 2 μm thick UC layer 11 disposed on the second light confinement layer 140. The quartz plate 151 has a refractive index of 1.46 relative to light with a wavelength of 550 nm. The UC layer 11 has a refractive index of 1.5 relative to light with a wavelength of 550 nm. The second light confinement layer 140 is made of SiN and has a refractive index of 2.0 relative to light with a wavelength of 550 nm. The base layer 120a of the PC layer 120 is made of SiN (with a refractive index of 2.0 relative to light with a wavelength of 550 nm), and multiple regions 120b with different refractive indices are vacancies disposed in the base layer 120a. Furthermore, the planar shape of the prepared regions 120b with different refractive indices is similar to... Figure 49 (a) Similarly, pattern 1 with FF = 10% ( Figure 49 (d) Refer to) and Pattern 4 with FF=30% (Refer to) Figure 49 (e)).

[0339] according to Figure 49 As shown in Table (c), the distribution ratio Γ of light existing in UC layer 11 is... UC Model 100I, with structure II, has a higher accuracy. Regarding the diffraction intensity κ... 2,0 Both Pattern 1 and Pattern 2 have a larger model 100H with structure I. Among them, for both model 100H with structure I and model 100I with structure II, the diffraction intensity κ of Pattern 4 is larger than that of Pattern 1. 2,0 Relatively large.

[0340] Figure 50 (a)~ Figure 50 (f) is a graph showing the calculation results of the thickness dependence of UC layer 11. Figure 50 (a) An example of the cross-sectional structure of the prepared optical device (including a resonator section model of the second light confinement layer 140 and the PC layer 120). Figure 50 (b) indicates the hole shape used for calculation. Figure 50 (c)~ Figure 50 (f) represents the diffraction intensity κ. 2,0 Distribution ratio Γ PC (The proportion of light present in the PC layer), distribution ratio ΓUC and effective refractive index n eff A table showing the calculation results for each.

[0341] Figure 50 Model 100J shown in (a) has a structure in which a laminate consisting of a PC layer 120, a second light-confining layer 140, and a UC layer 11 is sandwiched between a pair of quartz plates 151 and 152. Both quartz plates 151 and 152 have a refractive index of 1.46 for light with a wavelength of 550 nm. The UC layer 11 has a refractive index of 1.5 for light with a wavelength of 550 nm and a thickness of 20 nm to 2 μm. The second light-confining layer 140 is composed of TiO2 and has a refractive index of 2.5 for light with a wavelength of 550 nm. Furthermore, the second light-confining layer 140 has a thickness of 10 nm. The base layer 120a of the PC layer 120 is composed of SiN and has a refractive index of 2.0 for light with a wavelength of 550 nm. Multiple regions 120b with different refractive indices are obtained by filling TiO2 into holes provided in the base layer 120a. Furthermore, the planar shapes of the different refractive index regions 120b of the PC layer 120 are as follows: Figure 50 (b) shows an isosceles right triangle with FF of 30%.

[0342] Figure 50 (c) For the combination of PC layers 120 with thicknesses of 30 nm, 50 nm, and 100 nm and UC layers 11 with thicknesses of 50 nm, 100 nm, 200 nm, 500 nm, 1000 nm, and 2000 nm, the diffraction intensity κ represents... 2,0 The calculation results. Figure 50 (d) For the combination of PC layers 120 with thicknesses of 30 nm, 50 nm, and 100 nm and UC layers 11 with thicknesses of 50 nm, 100 nm, 200 nm, 500 nm, 1000 nm, and 2000 nm, the distribution ratio Γ is represented. PC The calculation results. Figure 50 (e) For the combination of PC layers 120 with thicknesses of 30 nm, 50 nm, and 100 nm and UC layers 11 with thicknesses of 50 nm, 100 nm, 200 nm, 500 nm, 1000 nm, and 2000 nm, the distribution ratio Γ is represented. UC The calculation results. Furthermore... Figure 50 (f) For the combination of PC layers 120 with thicknesses of 30 nm, 50 nm, and 100 nm and UC layers 11 with thicknesses of 50 nm, 100 nm, 200 nm, 500 nm, 1000 nm, and 2000 nm, the effective refractive index (equivalent refractive index) n is represented. eff The calculation results.

[0343] According to these Figure 50 (c)~ Figure 50The results of (f) show that the UC layer 11 is particularly less susceptible to thickness variations when it has a thickness of more than 200 nm.

[0344] Figure 51 It is for those who have Figure 50 (a) shows a cross-sectional structure of an optical device, and the table summarizes the dependence of the thickness of the light confinement layer (second light confinement layer 140) on the thickness of the PC layer 120. Especially... Figure 51 In the upper section, for the combination of TiO2 layers (second light confinement layer 140) with thicknesses of 0 nm, 5 nm, 10 nm, 20 nm, 30 nm, 50 nm, and 100 nm and PC layers 120 with thicknesses of 10 nm, 20 nm, 30 nm, 50 nm, and 100 nm, the diffraction intensity κ is represented. 2,0 (cm -1 The calculation results. Furthermore, in Figure 51 In the lower section, for the combination of TiO2 layers (second light confinement layer 140) with thicknesses of 0 nm, 5 nm, 10 nm, 20 nm, 30 nm, 50 nm, and 100 nm and PC layers 120 with thicknesses of 10 nm, 20 nm, 30 nm, 50 nm, and 100 nm, the distribution ratio Γ is represented. UC The calculation results.

[0345] according to Figure 51 The calculation results allow for a relatively large setting of the diffraction intensity κ. 2,0 and distribution ratio Γ UC The optimal range for both, i.e., the diffraction intensity κ 2,0 1000 (cm) -1 The above and the distribution ratio Γ UC The thickness of the PC layer 120 is 30 nm to 50 nm, and the thickness of the TiO2 layer (second light confinement layer 140) directly disposed on the PC layer 120 is 0 nm to 10 nm. Figure 51 The optimal range is enclosed by a solid line.

[0346] Furthermore, for optical devices with a fourth structure, the optimal range of the thickness of the light confinement layer 140 and the thickness of the PC layer 120 (phase modulation layer) is studied. Figure 52 (a) shows an example of the cross-sectional structure of an optical device (including a resonator section model of the second light confinement layer 140 and the PC layer 120) prepared for research. Figure 52 (b)~ Figure 52 (e) represents the diffraction intensity κ. 2,0 Distribution ratio Γ PC (The proportion of light present in the PC layer), distribution ratio Γ UC and effective refractive index neff The respective calculation results are presented in a table. Among them, Figure 52 (b)~ Figure 52 (e), representing the relationship between the "thickness of the optical confinement layer" and the "thickness of the phase modulation layer", indicates various calculation results, which essentially refer to the "thickness of the optical confinement layer" and the "thickness of the PC layer".

[0347] Figure 52 Model 100K shown in (a) consists of a quartz plate 151, a second light confinement layer 140 (PC layer 120 embedded in the surface region) with a thickness of 50 nm to 200 nm disposed on the quartz plate 151, and a UC layer 11 with a thickness of 2 μm disposed on the second light confinement layer 140. The base layer 120a of the PC layer 120 is the surface region of the second light confinement layer 140, and multiple recesses are provided on the surface of the second light confinement layer 140 as multiple regions 120b with different refractive indices. The quartz plate 151 has a refractive index of 1.46 for light with a wavelength of 550 nm. The UC layer 11 has a refractive index of 1.5 for light with a wavelength of 550 nm. The second light confinement layer 140 is made of TiO2 and has a refractive index of 2.5 for light with a wavelength of 550 nm. The base layer 120a of PC layer 120 is the surface region of the second light-confining layer 140, and a portion of the UV-curable resin constituting UC layer 11 enters into each of the recesses defining a plurality of regions 120b with different refractive indices. Furthermore, the planar shape of each region 120b of PC layer 120 with different refractive indices is a right-angled triangle with an FF of 30%.

[0348] Figure 52 (b) For the combination of a second optical confinement layer 140 having thicknesses of 50 nm, 100 nm, and 200 nm and a PC layer 120 (phase modulation layer) having thicknesses of 10 nm, 20 nm, 50 nm, 100 nm, 150 nm, and 200 nm, the diffraction intensity κ is represented. 2,0 The calculation results. Figure 52 (c) For the combination of a second optical confinement layer 140 having thicknesses of 50 nm, 100 nm, and 200 nm and a PC layer 120 (phase modulation layer) having thicknesses of 10 nm, 20 nm, 50 nm, 100 nm, 150 nm, and 200 nm, the distribution ratio Γ is represented. PC The calculation results. Figure 52 (d) For the combination of a second optical confinement layer 140 with thicknesses of 50 nm, 100 nm, and 200 nm and a PC layer 120 (phase modulation layer) with thicknesses of 10 nm, 20 nm, 50 nm, 100 nm, 150 nm, and 200 nm, the distribution ratio Γ is represented. UC The calculation results. Furthermore... Figure 52(e) For the combination of a second optical confinement layer 140 having thicknesses of 50 nm, 100 nm, and 200 nm and a PC layer 120 (phase modulation layer) having thicknesses of 10 nm, 20 nm, 50 nm, 100 nm, 150 nm, and 200 nm, the effective refractive index (equivalent refractive index) n is represented. eff The calculation results.

[0349] in, Figure 52 (b)~ Figure 52 The region enclosed by the solid line in (e) is the optimal range. That is, the thickness of the second light confinement layer 140 is preferably in the range of 50 nm to 100 nm, and the thickness of the PC layer 120 (phase modulation layer) is preferably 50 nm.

[0350] Figure 53 (a) is a cross-sectional view of a light-emitting device having a light-confining layer of the first structure, manufactured by the upconversion material injection manufacturing method (second manufacturing method) of the fourth embodiment. Wherein, Figure 53 (a) indicates the state before the parts are cut by cutting lines Sa and Sb.

[0351] The second manufacturing step, specifically the manufacturing step of the UC layer 11, includes an injection step of the ultraviolet-curable resin (containing an upconversion material as the main material) constituting the UC layer 11. In this respect, it differs from the first manufacturing method described above, which manufactures the excitation light source 200A and optical devices 100C-100F as separate units and then assembles these units. That is, in this second manufacturing method, optical devices 100C-100F, which are common to multiple excitation light sources 200A, are prepared, and then... Figure 53 (a) shows the cutting lines Sa and Sb(a), which cut the finished product, thereby obtaining Figure 45 The light-emitting device shown in (a)

[0352] Specifically, in Figure 53 In the example shown in (a) (before cutting), multiple excitation light sources 200A are provided for the common optical device 100C. Each excitation light source 200A can be replaced with the excitation light sources 20A-20C of the first to third embodiments and the first to tenth variations described above, and the basic structure has Figure 40The cross-sectional structure is shown by arrow (c). That is, each excitation light source 200A includes: a semiconductor substrate 21 made of GaAs; a first capping layer 24 disposed on the main surface 21a of the semiconductor substrate 21; an active layer 22 disposed on the first capping layer 24; a PC layer 23 disposed on the active layer 22; a second capping layer 25 disposed on the PC layer 23; a contact layer 26 disposed on the second capping layer 25; a second electrode 28 disposed on the contact layer 26; a first electrode 27 disposed on the area of ​​the main surface 21a of the semiconductor substrate 21 that is not covered by the semiconductor laminate containing the active layer 22 and the PC layer 23; and an insulating layer 290 made of SiN or the like covering the main surface 21a and the surface of the semiconductor laminate, excluding the first electrode 27 and the second electrode 28. The PC layer 23 is composed of a base layer 23a made of GaAs and multiple regions 23b with different refractive indices defined by vacancies disposed in the base layer 23a.

[0353] On the other hand, a common optical device 100C is mounted on the excitation light source 200A (on the back side 21b of the semiconductor substrate 21) through a first light-confining layer 130 composed of a dielectric multilayer film (or a single-layer structure composed of SiN, TiO2, etc.). This common optical device 100C includes: a light-transmitting substrate 15; a second light-confining layer 140 having a first structure disposed on one side of the substrate 15; a PC layer 120 (or a phase modulation layer) embedded in the interior or surface region of the second light-confining layer 140; a UC layer 11 sandwiched between the PC layer 120 and the first light-confining layer 130; and the first light-confining layer 130. Particularly between the PC layer 120 and the first light-confining layer 130, a spacer 110 (a UV-curing resin containing multiple beads) is configured to prevent leakage of the UV-curing resin and define the thickness of the UC layer 11 in order to inject the UV-curing resin constituting the UC layer 11. In addition, in this space, in order to suppress shrinkage near the center of the UV-cured UC layer 11 (suppressing thickness variation of the UC layer 11 relative to the first light-limiting layer 130), a separating member 111 made of UV-curable resin is also provided.

[0354] In this optical device 100C, the second light confinement layer 140 has a base 141 and a capping layer 142, each composed of a monolayer structure of SiN or TiO2. A PC layer 120 is located between the base 141 and the capping layer 142, and includes a base layer 120a and multiple regions 120b with different refractive indices. The base layer 120a also has a monolayer structure composed of SiN or TiO2. The multiple regions of the PC layer 120 with different refractive indices are voids. The capping layer 142 also has a monolayer structure composed of SiN or TiO2. Here, when the base 141 and the base layer 120a of the PC layer 120 are composed of different materials (for example, when the base 141 is composed of SiN and the base layer 120a is composed of TiO2), the structure of this optical device 100C is substantially the same as... Figure 40 The structure of the optical device 100A, indicated by arrow (a) in the diagram, is consistent with that of the optical device 100A. On the other hand, when the base 141, the base layer 120a of the PC layer 120, and the capping layer 142 are made of the same material (e.g., each made of SiN), the structure of the optical device 100C is substantially the same as that of the optical device 100C. Figure 40 The structure of the optical device 100B shown by arrow (b) is consistent with that of the PC layer 120, which is embedded inside the second light confinement layer 140 having a single-layer structure.

[0355] The light-emitting device obtained by the above-described upconversion material injection type manufacturing method (second manufacturing method), especially the individual light-emitting devices cut by the cutting lines Sa and Sb (the fourth embodiment where the second light confinement layer 140 has the first structure), does not subject the UC layer 11 provided on the substrate 15 to unnecessary heat. Furthermore, the multiple regions 120b (gaps) with different refractive indices provided on the PC layer 120 are not filled with upconversion material. Moreover, before mounting the optical device 100C to the excitation light source 200A, the initial optical characteristics of the photonic crystal surface-emitting laser can be measured.

[0356] Furthermore, according to this second manufacturing method, a large number of light-emitting devices with the same structure can be obtained through a single device manufacturing process, and the size of each device can be reduced. In addition, since the thickness of the UC layer 11 is defined by the spacer 110, high-precision thickness control is possible. Because the thickness of the UC layer 11 can be controlled with high precision, the thickness of the UC layer 11 becomes optimal, effectively suppressing the generation of unwanted vertical modes. Furthermore, since the UC layer 11 can be manufactured parallel to other layers such as the substrate 15, waveguide loss of visible in-plane resonant modes can also be suppressed.

[0357] Figure 53 (b) is a cross-sectional view of a light-emitting device having a light-confining layer of the second structure, manufactured by the second manufacturing method. Wherein... Figure 53(b) also represents the state before the parts are cut apart by the cutting lines Sa and Sb.

[0358] Should Figure 53 (b) The light-emitting device (before cutting off) includes a plurality of excitation light sources 200A and a common optical device 100D that abuts against these excitation light sources 200A through the first light confinement layer 130. Figure 53 (b) The light-emitting device shown has, except for the point where the common optical device 100D has the PC layer 120 of the second structure, the same as... Figure 53 (a) has the same structure as the light-emitting device.

[0359] That is, a common optical device 100D is mounted on multiple excitation light sources 200A (on the back side 21b of the semiconductor substrate 21) through a first light confinement layer 130 composed of a dielectric multilayer film (or it may have a single-layer structure composed of SiN, TiO2, etc.). The common optical device 100D includes: a light-transmitting substrate 15; a second light confinement layer 140 having a second structure disposed on one side of the substrate 15; a PC layer 120 (or a phase modulation layer) embedded in the surface region of the second light confinement layer 140; a UC layer 11 sandwiched between the PC layer 120 and the first light confinement layer 130; and the first light confinement layer 130.

[0360] In this common optical device 100D, the second light confinement layer 140 has: a base 141 with a monolayer structure made of SiN; and a capping layer 142 with a monolayer structure made of TiO2. A PC layer 120 is located between the base 141 and the capping layer 142, and includes a base layer 120a and multiple regions 120b with different refractive indices. The base layer 120a also has a monolayer structure made of SiN and substantially constitutes part of the second light confinement layer 140. The multiple regions with different refractive indices of the PC layer 120 are defined by multiple recesses provided in the base layer 120a constituting part of the second light confinement layer 140, and TiO2 material of the same material as the capping layer 142 is filled in these multiple recesses. Particularly between the PC layer 120 and the first light confinement layer 130, a spacer 110 is provided to prevent leakage of the UV-curing resin constituting the UC layer 11 and to define the thickness of the UC layer 11 in order to inject the UV-curing resin constituting the UC layer 11. In addition, in this space, in order to suppress shrinkage near the center of the UV-cured UC layer 11 (suppressing thickness variation of the UC layer 11 relative to the first light-limiting layer 130), a separating member 111 made of UV-curable resin is also provided.

[0361] Here, when the base 141 and the base layer 120a of the PC layer 120 are made of different materials (e.g., the base 141 is made of SiN and the base layer 12a is made of TiO2), the structure of the common optical device 100D is substantially the same as... Figure 40 The structure of the optical device 100A, indicated by arrow (a), is consistent with that of the other two optical devices. In this case, the base layer 120a and the multiple regions 120b with different refractive indices are made of the same material, but the refractive index of the base layer 120a differs from that of the multiple regions 120b. On the other hand, when the base layer 120a of the abutment 141 and the PC layer 120 are made of the same material (e.g., both are made of SiN), the structure of this common optical device 100D is substantially the same as that of the other two optical devices. Figure 40 The structure of the optical device 100B shown by arrow (b) is consistent with that of the PC layer 120, which is embedded in the surface region of the second light confinement layer 140 having a single-layer structure.

[0362] Through this Figure 53 The light-emitting devices shown in (b), especially the cut-off light-emitting devices (the fourth embodiment where the second light-confining layer 140 has the second structure), can also obtain the same... Figure 45 The same effect is achieved by the light-emitting device shown in (a). Furthermore, this... Figure 53 The manufacturing method of the light-emitting device shown in (b) can also produce the same result as described above. Figure 53 The manufacturing method of the light-emitting device shown in (a) has the same effect.

[0363] Figure 54 (a) is a cross-sectional view of a light-emitting device having a light-confining layer of the third structure manufactured by the second manufacturing method. Wherein, Figure 54 (a) also represents the state before each part is cut by the cutting lines Sa and Sb.

[0364] Should Figure 54 (a) The light-emitting device (before cutting off) includes a plurality of excitation light sources 200A and a common optical device 100E that abuts against these excitation light sources 200A through a first light confinement layer 130. Figure 54 The light-emitting device shown in (a) has, except for the point where the common optical device 100E has the PC layer 120 of the third structure, the same as... Figure 53 (a) has the same structure as the light-emitting device.

[0365] That is, a common optical device 100E is mounted on multiple excitation light sources 200A (on the back side 21b of the semiconductor substrate 21) through a first light confinement layer 130 composed of a dielectric multilayer film (or it may have a single-layer structure composed of SiN, TiO2, etc.). The common optical device 100E includes: a light-transmitting substrate 15; a second light confinement layer 140 having a third structure disposed on one side of the substrate 15; a PC layer 120 (or a phase modulation layer) embedded in the surface region of the second light confinement layer 140; a UC layer 11 sandwiched between the PC layer 120 and the first light confinement layer 130; and the first light confinement layer 130.

[0366] In this common optical device 100E, the second light-confining layer 140 has a single-layer structure made of SiN, and multiple recesses are formed on its surface to define multiple regions 120b with different refractive indices of the PC layer 120. Therefore, the surface region of the second light-confining layer 140, which has multiple recesses, becomes the base layer 120a of the PC layer 120. In the PC layer 120 of this third structure, the surface of the second light-confining layer 140 and the inner walls (including the bottom) of the multiple recesses are covered by a capping layer 120c made of TiO2. Furthermore, between the PC layer 120 and the first light-confining layer 130, a spacer 110 is provided to prevent leakage of the UV-curing resin constituting the UC layer 11 and to define the thickness of the UC layer 11 for injecting the UV-curing resin constituting the UC layer 11. In addition, in this space, a separator 111 made of UV-curing resin is also provided to suppress shrinkage near the center of the UV-cured UC layer 11 (suppress thickness variation of the UC layer 11 relative to the first light-confining layer 130).

[0367] The common optical device 100E, having the PC layer 120 of the third structure, is substantially similar to... Figure 40 The structure of the optical device 100B shown by arrow (b) is consistent with that of the PC layer 120, which is embedded in the surface region of the second light confinement layer 140 having a single-layer structure.

[0368] Using this Figure 54 The light-emitting devices shown in (a), especially the cut-off light-emitting devices (the fourth embodiment where the second light-confining layer 140 has the second structure), can also obtain the same... Figure 45 The light-emitting device shown in (a) achieves the same effect. Moreover, this... Figure 53 The manufacturing method of the light-emitting device shown in (b) can also produce the same result as described above. Figure 53 The manufacturing method of the light-emitting device shown in (a) has the same effect.

[0369] Figure 54(b) is a cross-sectional view of a light-emitting device having a light-confining layer of the fourth structure, manufactured by the second manufacturing method. Figure 54 (b) also indicates the state before the parts are cut apart by the cutting lines Sa and Sb.

[0370] Should Figure 54 (b) The light-emitting device (before cutting off) includes a plurality of excitation light sources 200A and a common optical device 100F that abuts against these excitation light sources 200A through the first light confinement layer 130. Figure 54 (b) The light-emitting device shown has, except for the point where the common optical device 100F has the PC layer 120 of the fourth structure, the same as... Figure 53 (a) has the same structure as the light-emitting device.

[0371] That is, a common optical device 100F is mounted on multiple excitation light sources 200A (on the back side 21b of the semiconductor substrate 21) through a first light confinement layer 130 composed of a dielectric multilayer film (or it may have a single-layer structure composed of SiN, TiO2, etc.). The common optical device 100F includes: a light-transmitting substrate 15; a second light confinement layer 140 having a fourth structure disposed on one side of the substrate 15; a PC layer 120 (or a phase modulation layer) embedded in the surface region of the second light confinement layer 140; a UC layer 11 sandwiched between the PC layer 120 and the first light confinement layer 130; and the first light confinement layer 130.

[0372] In this common optical device 100F, the second light-confining layer 140 has a single-layer structure made of SiN, and multiple recesses are formed on its surface to define multiple regions 120b with different refractive indices of the PC layer 120. Therefore, the surface region of the second light-confining layer 140, which has multiple recesses, becomes the base layer 120a of the PC layer 120. In this fourth structure of the PC layer 120, the surface of the second light-confining layer 140 and the inner walls (including the bottom) of the multiple recesses are directly covered by the UC layer 11, becoming part of the UC layer 11 and filling each of the multiple recesses. Furthermore, between the PC layer 120 and the first light-confining layer 130, a spacer 110 is provided to prevent leakage of the ultraviolet-curing resin constituting the UC layer 11 and to define the thickness of the UC layer 11 for injecting the ultraviolet-curing resin constituting the UC layer 11. Furthermore, in this space, in order to suppress shrinkage near the center of the UV-cured UC layer 11 (suppressing thickness variation of the UC layer 11 relative to the first light-limiting layer 130), a separating member 111 made of UV-curable resin is also provided.

[0373] The common optical device 100F, having the PC layer 120 of the fourth structure, is substantially similar to... Figure 40The structure of the optical device 100B shown by arrow (b) is consistent with that of the PC layer 120, which is embedded in the surface region of the second light confinement layer 140 having a single-layer structure.

[0374] Using this Figure 54 The light-emitting devices shown in (b), especially the cut-off light-emitting devices (the fourth embodiment where the second light-confining layer 140 has the second structure), can obtain the same as Figure 45 The light-emitting device shown in (a) achieves the same effect. Moreover, this... Figure 53 The manufacturing method of the light-emitting device shown in (b) can also produce the same result as described above. Figure 53 The manufacturing method of the light-emitting device shown in (a) has the same effect.

[0375] Next, the manufacturing method of the above-mentioned upconversion material injection type (the second manufacturing method) will be described. Figure 55 (a)~ Figure 58 (d) is used as an example to describe the situation where... Figure 54 (a) is a diagram illustrating the manufacturing process of the light-emitting device with the light-containment layer of the third structure shown.

[0376] First, such as Figure 55 As shown in (a), on one side (main side 21a) of the prepared GaAs substrate 21, a first capping layer 24 (n-type capping layer), an active layer 22, and a base layer 23a forming a PC layer 23 are sequentially stacked using MO-CVD. On the other hand, on the other side (back side 21b) of the GaAs substrate 21, a dielectric multilayer film (infrared-transmitting visible reflector) is formed by vapor deposition or sputtering.

[0377] When the layers on both sides of the GaAs substrate 21 are formed, as Figure 55 As shown in (b), multiple recesses defining multiple regions 23b with different refractive indices are formed in the base layer 23a of the PC layer 23 by electron beam scanning and dry etching. Next, in Figure 55 In (c), a second capping layer 25 (p capping layer) and a contact layer 26 are sequentially stacked on a PC layer 23 consisting of a base layer 23a and multiple regions 23b with different refractive indices using the MO-CVD method.

[0378] The stacked portion disposed on the GaAs substrate 21 as described above, such as Figure 55 As shown in (d), the component portions (each including an excitation source 200A of the photonic crystal surface-emitting laser) are patterned using photolithography and wet etching (unwanted portions between components are etched). Then, as... Figure 56As shown in (a), an insulating layer 290 composed of SiN is deposited on one side (main side 21a) of GaAs substrate 21 and on the surface of the laminate using plasma CVD.

[0379] After the insulating layer 290 is stacked, a portion of the insulating layer 290 located between the components, such as Figure 56 As shown in (b), the patterning is removed using photolithography and wet etching. Further, the first electrode 27 (n electrode) is deposited using photolithography and vapor deposition. After vapor deposition, the first electrode 27 is alloyed in a hydrogen atmosphere. Then, as... Figure 56 As shown in (c), a portion of the insulating layer 290 located on the upper part of the stack where the contact layer 26 is located is removed (patterned) using photolithography and wet etching. The second electrode 28 (p electrode) is deposited by evaporation using photolithography and vapor deposition. The excitation light source 200A side is completed.

[0380] Next, the manufacturing process of the resonator section (optical components) will be explained. For example... Figure 56 As shown in (d), on one surface of a light-transmitting substrate 15 (e.g., a quartz plate), a SiN layer 140a, which should become the second light confinement layer 140, is laminated using a plasma CVD method. Further, as... Figure 57 As shown in (a), multiple recesses are formed on the surface of the SiN layer 140a using electron beam scanning and dry etching to define multiple regions 120b with different refractive indices of the PC layer 120. At this time, the surface region of the SiN layer 140a with multiple recesses becomes the base layer 120a, and these multiple recesses become multiple regions 120b with different refractive indices.

[0381] Next, a TiO2 layer 120c is formed on the surface of the SiN layer 140a (the surface of the base layer 120a) and on the inner walls and bottom of the multiple recesses (multiple regions with different refractive indices 120b), using atomic layer deposition (ALD). Figure 57 (b) shows the second light confinement layer 140.

[0382] On the other hand, on the excitation light source side ( Figure 56 (c)), such as Figure 57 As shown in (c), in order to define the space that should become the UC layer 11, a separating member 111 made of ultraviolet-curable resin is formed on the first light-confining layer 130. This separating member 111 is formed by patterning the ultraviolet-curable resin (the same material as the constituent material of the UC layer 11) coated on the first light-confining layer 130. Furthermore, on the first light-confining layer 130, as shown... Figure 57As shown in (d), spacers 110 are disposed along the edge of the GaAs substrate 21. Specifically, UV-curable resin in which beads for the spacers 110 are dispersed is coated onto the first light-containing layer 130. At this stage, the resin injection opening 112 (an opening for injecting resin containing upconversion material) is set to be open beforehand. In this way, by coating the spacers 110, parallelism can be guaranteed over a wide range (wafer size).

[0383] After that, as Figure 58 As shown in (a), Figure 57 (d) shows the excitation source side and Figure 57 (b) The optical device shown is disposed in a vacuum in a combined state. In this state, a space with a UC layer 11 should be formed, such as... Figure 58 As shown in (b), a spacer 111 is disposed inside a spacer 110 (which contains a UV-cured resin layer with a plurality of beads) surrounded by a spacer 110 (with a resin injection opening 112).

[0384] Then, as Figure 58 As shown in (c), ultraviolet-curing resin (containing the same upconversion material as the spacer 111) is injected into the space secured by the spacer 110 through the resin injection opening 112. Then, ultraviolet light is irradiated from the substrate 15 side, and the injected ultraviolet-curing resin hardens. Figure 58 (d) is a top view showing the state of the UC layer 11 after UV curing. Then, by using a cutting method, the components are separated at the positions indicated by the cutting lines Sa and Sb. Figure 58 (c) shows the manufactured item being cut to obtain a product with... Figure 46 (a) shows the cross-sectional structure of the light-emitting device.

[0385] Explanation of symbols

[0386] 1A~1H,1J…light-emitting devices, 10A~10E,10A1,100A~100F…optical devices, 11…UC layer (upconversion layer), 12A,120…PC layer (photonic crystal layer), 12a,120a…basic layer, 11b,12b,12c,120b…different refractive index regions, 120c…TiO2 layer, 12B,12C…phase modulation layer, 13…first light-reflecting layer (first light-confining layer), 13a… Surface, 14… second light-reflecting layer (second light-confining layer), 110… spacer, 111… separator, 112… resin injection opening, 130… first light-confining layer, 140… second confinement layer, 141… base, 142… capping layer, 15… substrate, 16… dichroic mirror, 17… diffractive optical element, 20A, 20B, 20C, 200A… excitation light source, 21… semiconductor substrate, 21a… main surface, 21b… back surface, 22… active layer 23…PC layer, 23a…base layer, 23b…regions with different refractive indices, 24…first capping layer, 25…second capping layer, 26…contact layer, 27…first electrode (n electrode), 27a…opening, 28…second electrode (p electrode), 29…first DBR layer, 30…second DBR layer, 31…first electrode, 33…slit, 40…spatial light modulator, 41…lens, 42, 201, 202…excitation source, 290…insulator Layer, 500… base, 510… p electrode pad, 520… n electrode pad, E1… first optical image portion, E2… second optical image portion, E3… 0th order light, D… straight line, G… centroid, Lex, Lex1, Lex2… excitation light, Lout… light, Lout1… laser, Lout2… optical image, O… lattice point, Q… center, R… unit constitutive region, RIN… inner region, ROUT… outer region, θ… tilt angle.

Claims

1. An optical device, characterized in that, include: An upconversion layer comprising an upconversion material that receives excitation light in a first wavelength region and outputs light in a second wavelength region shorter than the first wavelength region; The first light-reflecting layer has light-reflecting properties that reflect at least a portion of the light in the second wavelength region; A second light-reflecting layer, having light-reflecting properties that reflect a portion of the light in the second wavelength region while allowing the remainder to pass through, is configured such that the upconversion layer is located between the first light-reflecting layer and the second light-reflecting layer; and A resonant mode forming layer is disposed between the upconversion layer and the first light reflection layer, or between the upconversion layer and the second light reflection layer, and includes a base layer and a plurality of regions with different refractive indices having a different refractive index than the base layer and distributed in a two-dimensional manner on a reference plane perpendicular to the thickness direction of the resonant mode forming layer, and forming a resonant mode of light in the second wavelength region along the reference plane.

2. An optical device, characterized in that, include: An upconversion layer comprising an upconversion material that receives excitation light in a first wavelength region and outputs light in a second wavelength region shorter than the first wavelength region; The first light confinement layer has light reflection properties that reflect at least a portion of the light in the second wavelength region; A second light-containing layer, having light-reflecting properties that reflect a portion of the light in the second wavelength region while allowing the remainder to pass through, is configured such that the upconversion layer is located between the first light-containing layer and the second light-containing layer; and A resonant mode forming layer is disposed between the upconversion layer and the first light confinement layer, or between the upconversion layer and the second light confinement layer, and includes a base layer and a plurality of regions with different refractive indices having a different refractive index than the base layer and distributed in a two-dimensional manner on a reference plane perpendicular to the thickness direction of the resonant mode forming layer, and forming a resonant mode of light in the second wavelength region along the reference plane.

3. The optical device as described in claim 2, characterized in that, The first light confinement layer and the second light confinement layer each include: a light reflective layer having a multilayer stacked structure, or a single layer made of a single material having a substantially uniform refractive index distribution along the thickness direction from the first light confinement layer toward the second light confinement layer and having a refractive index lower than that of the upconversion layer.

4. The optical device as described in claim 2, characterized in that, The second light confinement layer has a portion of the second light confinement layer comprising a layer facing the upconversion layer constituting the base layer, and a single-layer structure having a plurality of recesses on the layer for defining the plurality of different refractive index regions.

5. An optical device, characterized in that, include: An upconversion layer comprising an upconversion material that receives excitation light in a first wavelength region and outputs light in a second wavelength region shorter than the first wavelength region; The first light confinement layer has light reflection properties that reflect at least a portion of the light in the second wavelength region; A second light-confining layer, having light-reflecting properties that reflect a portion of the light in the second wavelength region while allowing the remainder to pass through, is configured such that the upconversion layer is located between the first light-confining layer and the second light-confining layer, and has a single-layer structure in which a resonant mode of the light in the second wavelength region is formed therein; and A resonant mode forming layer that forms the resonant mode of light in the second wavelength region, and includes: a base layer disposed on the side of the layer of the second light confinement layer facing the upconversion layer, and constituting part of the second light confinement layer; and a plurality of regions with different refractive indices, defined by a plurality of recesses distributed in a two-dimensional manner on the layer of the second light confinement layer, which serves as a reference plane perpendicular to the thickness direction of the resonant mode forming layer, and having a refractive index different from that of the base layer.

6. The optical device as described in any one of claims 1 to 5, characterized in that, The resonant mode forming layer is a photonic crystal layer in which multiple regions with different refractive indices are arranged periodically.

7. The optical device according to any one of claims 1 to 5, characterized in that, It is an optical device that outputs optical images. In an imaginary square lattice set on a reference plane that should have the plurality of regions with different refractive indices, the plurality of regions with different refractive indices are respectively configured such that, with their centroids separated from the corresponding lattice points of the imaginary square lattice by a predetermined distance, the line segment connecting the centroid and the corresponding lattice point has a rotation angle relative to the imaginary square lattice corresponding to the optical image.

8. The optical device as described in any one of claims 1 to 5, characterized in that, It is an optical device that outputs optical images. In an imaginary square lattice set on the reference plane on which the plurality of different refractive index regions are to be formed, the centroid of each of the plurality of different refractive index regions is located on a straight line that passes through the corresponding lattice point of the imaginary square lattice and is inclined relative to the square lattice, and the distance between the centroid and the corresponding lattice point is individually set according to the optical image.

9. The optical device as described in any one of claims 2 to 5, characterized in that, It also includes a diffractive optical element disposed on the opposite side of the upconversion layer relative to the second light confinement layer.

10. The optical device according to any one of claims 2 to 5, characterized in that, It also includes a spatial light modulator disposed on the opposite side of the upconversion layer relative to the second light confinement layer.

11. The optical device as described in any one of claims 2 to 5, characterized in that, Also includes: A dichroic mirror is disposed on the opposite side of the upconversion layer relative to the second light-confining layer, and the light transmittance in the second wavelength region is greater than the light transmittance in the first wavelength region.

12. The optical device according to any one of claims 1 to 5, characterized in that, The first wavelength region is the near-infrared region, and the second wavelength region is the visible region.

13. A light-emitting device, characterized in that, include: The optical device according to any one of claims 2 to 5; and An excitation light source is integrated with the optical device via the first light confinement layer and supplies the excitation light to the upconversion layer.

14. The light-emitting device as described in claim 13, characterized in that, The excitation source includes a photonic crystal surface-emitting laser disposed on the opposite side of the upconversion layer relative to the first optical confinement layer. The light transmittance in the first wavelength region of the first light confinement layer is greater than the light transmittance in the second wavelength region of the first light confinement layer.

15. The light-emitting device as described in claim 14, characterized in that, The area of ​​the photonic crystal layer of the photonic crystal surface-emitting laser, viewed from the stacking direction of the laser, is larger than the area of ​​the upconversion layer, viewed from the stacking direction of the optical device.

16. The light-emitting device as described in claim 15, characterized in that, The photonic crystal surface-emitting laser has the following characteristics: A semiconductor substrate having a front side and a back side; A semiconductor stack disposed on the main surface of the semiconductor substrate, and comprising an active layer and a photonic crystal layer; A first electrode made of metal is disposed on the back side of the semiconductor substrate; and The second electrode is disposed on the semiconductor stack. The first electrode has an opening for the excitation light to pass through. At least a portion of the first light-confining layer is disposed within the opening of the first electrode.

17. The light-emitting device as described in claim 14, characterized in that, The excitation source includes a plurality of photonic crystal surface-emitting lasers disposed on the opposite side of the upconversion layer relative to the first optical confinement layer and having the same structure as the photonic crystal surface-emitting lasers. The plurality of photonic crystal surface-emitting lasers are arranged in a one-dimensional or two-dimensional manner along the surface of the first optical confinement layer.

18. The light-emitting device as described in claim 14 or 17, characterized in that, The photonic crystal surface-emitting laser has the following characteristics: A semiconductor substrate having a front side and a back side; A semiconductor stack disposed on the main surface of the semiconductor substrate, and comprising an active layer and a photonic crystal layer; The first electrode is disposed on the back side of the semiconductor substrate and is composed of a transparent conductive film; and The second electrode is disposed on the semiconductor stack. The excitation light passes through the first electrode and reaches the first light confinement layer.

19. The light-emitting device as described in claim 14, characterized in that, The area of ​​the photonic crystal layer of the photonic crystal surface-emitting laser, viewed from the stacking direction of the photonic crystal surface-emitting laser, is smaller than the area of ​​the upconversion layer, viewed from the stacking direction of the optical device.

20. The light-emitting device as claimed in claim 19, characterized in that, The photonic crystal surface-emitting laser has the following characteristics: A semiconductor substrate having a front side and a back side; A semiconductor stack disposed on the main surface of the semiconductor substrate, and comprising an active layer and a photonic crystal layer; The first electrode is disposed on the exposed area of ​​the main surface of the semiconductor substrate that is not covered by the semiconductor laminate; and The second electrode is disposed on the semiconductor stack. The first light-confining layer is disposed on the back side of the semiconductor substrate.

21. The light-emitting device as described in claim 20, characterized in that, The excitation source includes a plurality of photonic crystal surface-emitting lasers disposed on the opposite side of the upconversion layer relative to the first optical confinement layer and having the same structure as the photonic crystal surface-emitting lasers. The plurality of photonic crystal surface-emitting lasers are arranged in a one-dimensional or two-dimensional manner along the surface of the first optical confinement layer.

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