Light emitting device and light source apparatus

Abstract

To provide a light-emitting device capable of miniaturizing a light source device that collects and outputs light.SOLUTION: A light-emitting device 1 an M-point oscillation S-iPM laser having a phase modulation layer 15. In-plane wavenumber vectors K1 to K4 in four directions each including a wavenumber spread corresponding to the angular spread of the emitted light from the light emitting device 1 are formed on the reciprocal lattice space of the phase modulation layer 15. The magnitude of at least one of the in-plane wavenumber vectors K1 to K4 is smaller than 2π / λ (light line). A predetermined phase distribution φ(x, y) included in the phase modulation layer 15 includes elements for condensing emitted light.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present disclosure relates to a light emitting device and a light source apparatus. [Background technology]

[0002] Patent Document 1 discloses a technique for removing zero-order light contained in the output of a static-integrable phase modulating (S-iPM) laser. The light-emitting element disclosed in this document includes an active layer and a phase modulation layer. The phase modulation layer includes a basic layer and a plurality of modified refractive index areas that have a different refractive index from the basic layer and are distributed two-dimensionally in a plane perpendicular to the thickness direction of the phase modulation layer. When a virtual square lattice is set in the plane, the center of gravity of each modified refractive index area is disposed away from the corresponding lattice point and has a rotation angle around the lattice point according to the phase distribution according to the optical image. The lattice spacing of the virtual square lattice and the emission wavelength of the active layer satisfy the condition for M-point oscillation. In the reciprocal lattice space of the phase modulation layer, the magnitude of at least one of the four in-plane wave vectors that each include a wave number spread corresponding to the angular spread of the optical image is smaller than 2π / λ.

[0003] Patent Document 2 discloses a technique related to a control device for a spatial light modulator. This control device includes a lens, a spatial light modulator, an imaging device, a calculation unit, an analysis unit, and a change unit. The spatial light modulator has a modulation surface on which a plurality of modulation pixels are two-dimensionally arranged, and presents a first modulation pattern on the modulation surface to form a first light spot and a second light spot on the pupil surface of the lens, and outputs a first modulated light. The imaging device has an imaging surface on which a plurality of photoelectric conversion pixels are two-dimensionally arranged, and captures a first stripe pattern image formed on the focal plane of the lens by the first modulated light on the imaging surface, and generates first image data representing the light intensity distribution of the first stripe pattern image. The calculation unit calculates at least one first parameter of intensity amplitude, phase shift amount, and intensity average based on the first image data. The analysis unit calculates a relative positional deviation between the optical axis of the lens and the reference coordinates of the modulation surface based on the first parameter. The change unit changes the origin position of the reference coordinates on the modulation surface so as to reduce the relative positional deviation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO 2020 / 45453 [Patent Document 2] JP 2016-224412 A Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, in devices equipped with a light source, optical components such as lenses are used as an optical system for converging light from the light source. When miniaturization of such a light source device is required, a significant miniaturization is possible if, for example, a semiconductor light-emitting element is used for the light source. On the other hand, miniaturization of optical components for converging light is difficult, which is a factor that hinders miniaturization of the light source device.

[0006] In view of the above, an object of the present disclosure is to provide a light emitting device that enables a light source apparatus that outputs light while concentrating it to be miniaturized, and a light source apparatus including the light emitting device. [Means for solving the problem]

[0007] The light emitting device according to the present disclosure includes a light emitting section and a phase modulation layer. The phase modulation layer is optically coupled to the light emitting section, and includes a basic layer and a plurality of modified refractive index areas that have a different refractive index from the basic layer and are distributed two-dimensionally in a plane perpendicular to the thickness direction. When a virtual square lattice is set in the plane, the centers of gravity of the modified refractive index areas are arranged in one of the following two forms: a first form in which the centers of gravity of the modified refractive index areas are arranged away from the corresponding lattice points and have individual rotation angles around the lattice points according to a predetermined phase distribution; and a second form in which the centers of gravity of the modified refractive index areas are arranged on a straight line that passes through the lattice points of the virtual square lattice and is inclined with respect to the square lattice, and the distance between the centers of gravity of the modified refractive index areas and the corresponding lattice points is individually set according to the predetermined phase distribution. The lattice spacing of the virtual square lattice and the emission wavelength λ of the light emitting section satisfy the condition of M-point oscillation. Four in-plane wave vectors, each including a wave number spread corresponding to the angular spread of the light emitted from the light emitting device, are formed in the reciprocal lattice space of the phase modulation layer. The magnitude of at least one in-plane wave vector is smaller than 2π / λ. The predetermined phase distribution includes an element for focusing the emitted light.

[0008] In the above light-emitting device, the centers of gravity of the multiple modified refractive index areas are arranged away from the corresponding lattice points of the virtual square lattice, and have individual rotation angles around the lattice points according to a predetermined phase distribution, or are arranged on a straight line that passes through the lattice points of the virtual square lattice and is inclined relative to the square lattice, and the distance between the center of gravity of each modified refractive index area and the corresponding lattice point is individually set according to the predetermined phase distribution. With this structure, an optical image of any shape can be generated as an S-iPM laser.

[0009] In addition, in this light-emitting device, the lattice spacing of the virtual square lattice and the emission wavelength of the light-emitting section satisfy the condition of M-point oscillation. Usually, in the standing wave state of M-point oscillation, the light propagating in the phase modulation layer is totally reflected, and the output of both the signal light (for example, at least one of +1st order light and -1st order light) and the 0th order light is suppressed. However, in this light-emitting device, in the reciprocal lattice space of the phase modulation layer, the standing wave is phase-modulated by the phase distribution, and forms four-directional in-plane wave vectors each including a wave number spread corresponding to the angular spread of the emitted light. The magnitude of at least one of these in-plane wave vectors is smaller than 2π / λ (i.e., the light line). In the S-iPM laser, such an in-plane wave vector can be adjusted by devising the arrangement of each modified refractive index area. When the magnitude of at least one in-plane wave vector is smaller than 2π / λ, the in-plane wave vector has a component in the thickness direction of the phase modulation layer and does not undergo total reflection at the interface with air. As a result, a part of the signal light is output from the phase modulation layer. However, when the condition of M-point oscillation is satisfied, the zeroth order light is not diffracted in the direction perpendicular to the surface, and is not output from the phase modulation layer into the light line. In other words, according to each of the light-emitting devices described above, the zeroth order light contained in the output of the S-iPM laser can be removed from the light line, and only the signal light can be output.

[0010] In addition, in this light-emitting device, the predetermined phase distribution includes an element for concentrating the emitted light. This allows the light-emitting device to output light while concentrating it. As described above, in this light-emitting device, the output of zero-order light that does not contribute to concentrating is suppressed, so that only signal light that can contribute to concentrating can be output. In this way, according to the light-emitting device, the light-emitting device itself can concentrate light, so that the optical components for concentrating light can be reduced and the light source device can be made smaller.

[0011] In the above light-emitting device, the element of the predetermined phase distribution may be an element for focusing the emitted light to at least two focusing points. According to each of the above light-emitting devices, it is also possible to focus the emitted light from one light-emitting device to at least two focusing points by appropriately designing the element for focusing included in the predetermined phase distribution. Therefore, the light source device can be further miniaturized.

[0012] In the light-emitting device, the predetermined phase distribution may include, as the element, a phase distribution obtained by combining a first phase distribution for emitting the emitted light toward at least two points and a second phase distribution for focusing the emitted light. For example, such an element can focus the emitted light to at least two focusing points.

[0013] In the light-emitting device, at least two of the light-focusing points may be aligned in a direction intersecting the thickness direction. In this case, the light-emitting device can be used for purposes such as causing light from each of the light-focusing points to interfere with each other.

[0014] In the light-emitting device, the element of the predetermined phase distribution is an element for focusing the emitted light to at least four focusing points, and the at least four focusing points may be distributed three-dimensionally. In this case, the light-emitting device can be used for applications such as creating a three-dimensional (stereoscopic) optical image.

[0015] In the above light-emitting device, the predetermined phase distribution may be a superposition of a hologram phase distribution that forms a plurality of bright spots arranged in a first direction and a lens phase distribution that has a light-condensing effect only in a second direction intersecting the first direction. In this case, a striped light image with little luminance unevenness can be obtained. Such a light image can improve the measurement accuracy in, for example, three-dimensional shape measurement.

[0016] In the above light-emitting device, the predetermined phase distribution is formed by superposing a hologram phase distribution forming a group of multiple bright spots arranged in a first direction and a lens phase distribution having a light-condensing effect only in a second direction intersecting the first direction, and each group of bright spots includes multiple bright spots, and the light intensities of at least two of the multiple bright spots may be different from each other. In this case, a striped light image with little unevenness in brightness can be obtained. Such a light image can improve the measurement accuracy in, for example, three-dimensional shape measurement. In addition, in this case, each group of bright spots includes a first bright spot, a second bright spot, and a third bright spot whose positions in the first direction are different from each other, the second bright spot and the third bright spot are arranged at positions sandwiching the first bright spot, and the light intensities of the second bright spot and the third bright spot may be smaller than the light intensity of the first bright spot. This makes it possible to obtain a light image in which the light intensity increases and decreases sinusoidally along the first direction.

[0017] In the above light-emitting device, the predetermined phase distribution may be a superposition of a hologram phase distribution that forms a plurality of bright spots arranged in a first direction and a lens phase distribution that has a light-collecting effect in the first direction and in a second direction intersecting the first direction and has a focal length in the first direction longer than that in the second direction. In this case, a striped light image with little luminance unevenness can be obtained. Such a light image can improve the measurement accuracy in, for example, three-dimensional shape measurement.

[0018] A first light source device according to the present disclosure includes a first and a second light emitting device that are any of the light emitting devices described above. The element of the predetermined phase distribution of the first light emitting device focuses a first output light from the first light emitting device toward a first focusing point. The element of the predetermined phase distribution of the second light emitting device focuses a second output light from the second light emitting device toward a second focusing point aligned with the first focusing point. This light source device generates interference fringes by making the first output light and the second output light interfere with each other.

[0019] A second light source device according to the present disclosure includes the above-mentioned light emitting device that focuses emitted light to at least two focusing points. The elements of the predetermined phase distribution of the light emitting device focus a first emitted light from the light emitting device toward the first focusing point and a second emitted light from the light emitting device toward the second focusing point. The light source device generates interference fringes by making the first emitted light and the second emitted light interfere with each other.

[0020] According to these light source devices, interference fringes are generated by the first and second emitted lights respectively emitted toward the first and second focusing points. The interference fringes are optical images in which the light intensity increases and decreases sinusoidally along a certain direction. Such optical images can be used, for example, for three-dimensional shape measurement. Furthermore, the light emitting devices included in these light source devices can be miniaturized as described above. Therefore, they can be placed in an extremely small space, such as inside a body, and three-dimensional shape measurement of a small space that was previously impossible becomes possible. Furthermore, since the phase distribution for focusing the emitted light is simpler than the phase distribution for directly generating the optical image of the interference fringes, noise generated in the optical image during calculation can be reduced. Therefore, an optical image having a light intensity that increases and decreases sinusoidally can be generated with high accuracy, and measurement errors in, for example, three-dimensional shape measurement can be reduced.

[0021] The first light source device may further include an optical system optically coupled to the first and second light emitting devices. In this case, the first light focusing point is located between the first light emitting device and the optical system. The second light focusing point is located between the second light emitting device and the optical system. The first emitted light and the second emitted light interfere with each other after passing through the optical system. The second light source device may further include an optical system optically coupled to the light emitting devices. In this case, the first and second light focusing points are located between the light emitting device and the optical system. The first emitted light and the second emitted light interfere with each other after passing through the optical system.

[0022] In this way, by providing the first and second light source devices with an optical system, it is possible to expand the irradiation area of ​​a light image having a light intensity that increases and decreases sinusoidally, regardless of the area of ​​the light emission surface of the light-emitting device. Effect of the Invention

[0023] According to the present disclosure, it is possible to provide a light emitting device that enables a light source apparatus that outputs light while concentrating it to be miniaturized, and a light source apparatus including the light emitting device. [Brief description of the drawings]

[0024] [Figure 1] 1 is a partially cross-sectional perspective view illustrating a configuration of a light-emitting device according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view showing a layered structure of a light-emitting device. [Diagram 3] FIG. 2 is a plan view of a phase modulation layer. [Figure 4] FIG. 2 is an enlarged view of a unit configuration area. [Diagram 5] FIG. 2 is a diagram illustrating a schematic view of a state in which emitted light is output from a light-emitting device according to an embodiment. [Figure 6] 1A is a diagram showing how the light-collecting points are arranged in a direction intersecting the thickness direction of the light-emitting device, and FIG. 1B is a diagram showing how the light-collecting points are distributed three-dimensionally. [Figure 7] 1A and 1B are diagrams illustrating a comparison between a light-emitting device according to an embodiment and a conventional S-iPM laser. [Figure 8] 11 is a plan view showing an example in which a substantially periodic refractive index structure is applied within a specific region of a phase modulation layer. FIG. [Figure 9] FIG. 2 is a diagram for explaining coordinate conversion from spherical coordinates to coordinates in an XYZ orthogonal coordinate system. [Figure 10] FIG. 2 is a plan view showing a reciprocal lattice space for a phase modulation layer of a light-emitting device that performs M-point oscillation. [Figure 11] FIG. 1 is a conceptual diagram illustrating a state in which a diffraction vector is added to an in-plane wave vector. [Figure 12]FIG. 13 is a diagram for illustrating a schematic structure surrounding a light line. [Figure 13] FIG. 13 is a diagram conceptually illustrating an example of a phase distribution. [Figure 14] FIG. 1 is a conceptual diagram for explaining a state in which a diffraction vector is added to the in-plane wave vectors in four directions, the wave number spread being removed. [Figure 15] FIG. 11 is a plan view showing another form of a phase modulation layer. [Figure 16] 16 is a diagram showing the arrangement of modified refractive index areas in the phase modulation layer shown in FIG. 15. FIG. [Figure 17] FIG. 13 is a diagram illustrating an example of a lens phase distribution. [Figure 18] FIG. 4 is a partially enlarged view of the lens phase distribution. [Figure 19] 13A and 13B are diagrams showing the results of an experiment in which a light-emitting device according to an embodiment was fabricated as a prototype and a near-field image was captured while the objective lens was moved in the Z direction. [Figure 20] 13A and 13B are diagrams showing the results of an experiment in which a light-emitting device according to an embodiment was fabricated as a prototype and a near-field image was captured while the objective lens was moved in the Z direction. [Figure 21] For comparison, a normal light emitting device (LED) not provided with a phase modulation layer was fabricated, and a near-field image was similarly captured. FIG. [Figure 22] 1A and 1B are diagrams illustrating how +1st order light and -1st order light are emitted from a phase modulation layer of a light-emitting device. [Figure 23] 11 is a diagram showing an example of a lens phase distribution and a phase distribution including a component corresponding to a non-zero vector. FIG. [Figure 24] FIG. 13 is a conceptual diagram of a method of dividing a hologram phase distribution and a lens phase distribution into a real part and an imaginary part, and synthesizing phases in each of the real part and the imaginary part. [Diagram 25] Parts (a) and (b) show examples of random patterns. [Figure 26] Parts (a) and (b) are diagrams showing the positions of the light-collecting points. [Figure 27] FIG. 1 shows near-field images of a light-emitting device fabricated in an experiment. [Figure 28] FIG. 1 shows near-field images of a light-emitting device fabricated in an experiment. [Figure 29] FIG. 1 shows near-field images of a light-emitting device fabricated in an experiment. [Diagram 30] Parts (a) and (b) are diagrams showing the positions of the light-collecting points. [Diagram 31] FIG. 1 shows near-field images of a light-emitting device fabricated in an experiment. [Diagram 32] FIG. 1 shows near-field images of a light-emitting device fabricated in an experiment. [Diagram 33] FIG. 1 shows near-field images of a light-emitting device fabricated in an experiment. [Diagram 34] FIG. 11 is a schematic diagram showing the configuration of a three-dimensional measurement system according to a second embodiment. [Diagram 35] FIG. 1 is a diagram illustrating a schematic configuration of a light source device. [Diagram 36] FIG. 13 is a diagram illustrating a schematic configuration of a light source device as another example of the light source device. [Figure 37] 4 is a diagram showing an interference light image on an image forming plane, that is, a pattern of measurement light. FIG. [Figure 38] 1 is a schematic diagram partially illustrating the configuration of a light source device according to a comparative example. [Figure 39] 13 is a diagram illustrating a schematic configuration when the angle θa of the emission direction is reduced. FIG. [Diagram 40] 13 is a schematic diagram partially showing the configuration of a light source device according to a modified example. FIG. [Diagram 41] 13A and 13B are diagrams for explaining the effect of providing a mask. [Diagram 42] FIG. 13 illustrates an example of a lens phase distribution for focusing light in only one direction. [Diagram 43] 42. (a) A diagram showing an example of an optical image formed on an imaginary plane by only a hologram phase distribution. (b) A diagram showing an optical image obtained by superimposing the lens phase distribution shown in FIG. 42 on the hologram phase distribution that forms the optical image shown in (a). [Diagram 44]This is a far-field image of a striped light image emitted from a prototype light-emitting device. [Diagram 45] For comparison, a far-field pattern is shown in the case where a striped light image is formed only by a hologram phase distribution, without using a lens phase distribution. [Figure 46] 44(a) and 44(b) are diagrams conceptually showing an operation for forming a striped light image different from that shown in FIG. 43. [Figure 47] 47(a) and (b) show an embodiment similar to that shown in FIG. 46. [Figure 48] This is a far-field image of a striped light image emitted from a prototype light-emitting device. [Figure 49] 47(a) and (b) show another embodiment similar to that shown in FIG. 46. [Figure 50] This is a far-field image of a striped light image emitted from a prototype light-emitting device. [Figure 51] FIG. 13 is a diagram illustrating an example of a lens phase distribution in which the focal length in the X direction is longer than the focal length in the Y direction. [Figure 52] (a) is a diagram showing a schematic example of an optical image formed only by a hologram phase distribution, and shows an optical image similar to that shown in Fig. 43(a). (b) is a diagram showing a schematic optical image obtained by superimposing the lens phase distribution shown in Fig. 51 on the hologram phase distribution that forms the optical image shown in (a). [Figure 53] This is a far-field image of a striped light image emitted from a prototype light-emitting device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Specific examples of the light-emitting device and light source apparatus of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. In the following description, the same elements in the description of the drawings will be given the same reference numerals, and duplicate descriptions will be omitted.

[0026] (First embodiment) Fig. 1 is a partially cutaway perspective view showing a configuration of a light-emitting device 1 according to an embodiment of the present disclosure. Fig. 2 is a cross-sectional view showing a layered structure of the light-emitting device 1. In Figs. 1 and 2, an XYZ orthogonal coordinate system is defined in which the axis extending in the thickness direction of the light-emitting device 1 at the center of the light-emitting device 1 is the Z axis.

[0027] The light-emitting device 1 is a laser light source that forms a standing wave in the XY plane direction and outputs a phase-controlled plane wave in a direction intersecting its thickness direction. The light-emitting device 1 is an S-iPM laser, and can output an optical image of any shape in a direction perpendicular to the main surface 10a of the semiconductor substrate 10 (i.e., the Z direction), a direction inclined thereto, or a direction including both.

[0028] 1 and 2, the light-emitting device 1 includes an active layer 12 as a light-emitting portion provided on a semiconductor substrate 10, a pair of clad layers 11 and 13 sandwiching the active layer 12, and a contact layer 14 provided on the clad layer 13. The semiconductor substrate 10, the clad layers 11 and 13, and the contact layer 14 are made of compound semiconductors such as GaAs-based semiconductors, InP-based semiconductors, or nitride-based semiconductors. The energy band gaps of the clad layer 11 and the clad layer 13 are larger than the energy band gap of the active layer 12. The thickness directions of the semiconductor substrate 10, the clad layer 11, the active layer 12, the clad layer 13, and the contact layer 14 coincide with the Z-axis direction.

[0029] The light-emitting device 1 further includes a phase modulation layer 15 optically coupled to the active layer 12. In this embodiment, the phase modulation layer 15 is provided between the active layer 12 and the cladding layer 13. The thickness direction of the phase modulation layer 15 coincides with the Z-axis direction. The phase modulation layer 15 may be provided between the cladding layer 11 and the active layer 12. An optical guide layer may be provided, if necessary, between at least one of the active layer 12 and the cladding layer 13 and the active layer 12 and the cladding layer 11. The optical guide layer may include a carrier barrier layer for efficiently confining carriers in the active layer 12.

[0030] The phase modulation layer 15 is configured to include a base layer 15a made of a first refractive index medium, and a plurality of modified refractive index areas 15b made of a second refractive index medium having a refractive index different from that of the first refractive index medium and present in the base layer 15a. The plurality of modified refractive index areas 15b include a lattice-like, approximately periodic structure. When the equivalent refractive index of the mode is n and the lattice spacing is a, the wavelength λ selected by the phase modulation layer 15 is 0 is λ 0 =(√2)a×n. This wavelength λ 0 is a wavelength included in the emission wavelength range of the active layer 12. The phase modulation layer 15 is configured to modulate the emission wavelength λ 0 The light entering the phase modulation layer 15 forms a predetermined mode in accordance with the arrangement of the modified refractive index areas 15b in the phase modulation layer 15, and is emitted to the outside from the surface of the light emitting device 1 as laser light.

[0031] The light emitting device 1 further includes an electrode 16 provided on the contact layer 14 and an electrode 17 provided on the back surface 10b of the semiconductor substrate 10. The electrode 16 makes ohmic contact with the contact layer 14. The electrode 17 makes ohmic contact with the semiconductor substrate 10. The electrode 17 has an opening 17a in a central region of the back surface 10b. The electrode 16 is provided in a central region of the surface of the contact layer 14. A portion of the contact layer 14 other than the electrode 16 is covered with a protective film 18 (see FIG. 2). The contact layer 14 not in contact with the electrode 16 may be removed to limit the current range. The back surface 10b of the semiconductor substrate 10 other than the region where the electrode 17 is provided is covered with an anti-reflection film 19, including the inside of the opening 17a. The anti-reflection film 19 in the other region other than the opening 17a may be removed.

[0032] In the light-emitting device 1, when a driving current is supplied between the electrodes 16 and 17, recombination of electrons and holes occurs in the active layer 12, causing the active layer 12 to emit light. The electrons and holes that contribute to this light emission, and the light generated in the active layer 12, are efficiently confined between the cladding layers 11 and 13.

[0033] The light emitted from the active layer 12 enters the phase modulation layer 15 and forms a predetermined mode according to the lattice structure inside the phase modulation layer 15. The laser light emitted from the phase modulation layer 15 is directly output from the rear surface 10b through the opening 17a to the outside of the light-emitting device 1. Alternatively, the laser light emitted from the phase modulation layer 15 is reflected by the electrode 16, and then output from the rear surface 10b through the opening 17a to the outside of the light-emitting device 1. At this time, the signal light included in the laser light is output in any direction including a direction perpendicular to the main surface 10a and a direction inclined relative to that direction.

[0034] It is this signal light that constitutes the light emitted from the light emitting device 1. The signal light is mainly the 1st order diffracted light or the -1st order diffracted light of the laser light (hereinafter referred to as the 1st order light and the -1st order light, respectively), or both. As will be described later, the output of the 0th order light of the laser light is suppressed from the phase modulation layer 15 of this embodiment.

[0035] FIG. 3 is a plan view of the phase modulation layer 15. As shown in the figure, the phase modulation layer 15 includes a base layer 15a made of a first refractive index medium and a plurality of modified refractive index areas 15b made of a second refractive index medium having a refractive index different from that of the first refractive index medium. In FIG. 3, a virtual square lattice is set in the XY plane for the phase modulation layer 15. One side of the square lattice is parallel to the X axis, and the other side is parallel to the Y axis. The square unit constituent regions R having a center at a lattice point O of the square lattice are two-dimensionally arranged over a plurality of columns along the X axis and a plurality of rows along the Y axis. The XY coordinates of each unit constituent region R are defined by the center of gravity of each unit constituent region R. These center of gravity positions coincide with the lattice point O of the virtual square lattice. The plurality of modified refractive index areas 15b are provided, for example, one by one, in each unit constituent region R. The planar shape of the modified refractive index area 15b is, for example, a circular shape. The lattice point O may be located outside the modified refractive index area 15b, or may be included inside the modified refractive index area 15b.

[0036] FIG. 4 is an enlarged view of the unitary constituent region R. As shown in the figure, each of the modified refractive index areas 15b has a center of gravity G. Here, the angle between the vector from the lattice point O toward the center of gravity G and the X-axis is α(x, y). x indicates the position of the x-th lattice point on the X-axis, and y indicates the position of the y-th lattice point on the Y-axis. When the rotation angle α is 0°, the direction of the vector connecting the lattice point O and the center of gravity G coincides with the positive direction of the X-axis. In addition, the length of the vector connecting the lattice point O and the center of gravity G is r(x, y). In one example, r(x, y) is constant throughout the phase modulation layer 15, regardless of x and y.

[0037] As shown in FIG. 3, the direction of the vector connecting the lattice point O and the center of gravity G, that is, the rotation angle α of the center of gravity G of the modified refractive index area 15b around the lattice point O, is set individually for each lattice point O according to the phase distribution φ(x, y) corresponding to the desired shape of the emitted light. In this disclosure, such an arrangement form of the center of gravity G is called the first form. The phase distribution φ(x, y) has a specific value for each position determined by the values ​​of x and y, but is not necessarily expressed by a specific function. The rotation angle distribution α(x, y) is determined by extracting the phase distribution φ(x, y) from the complex amplitude distribution obtained by Fourier transforming the desired shape of the emitted light. When determining the complex amplitude distribution from the desired shape of the emitted light, it is advisable to apply an iterative algorithm such as the Gerchberg-Saxton (GS) method, which is generally used in calculations for hologram generation. In this case, it is possible to improve the reproducibility of the beam pattern.

[0038] FIG. 5 is a schematic diagram showing how the output light Lout is output from the light emitting device 1 of the present embodiment. As shown in the figure, the light emitting device 1 of the present embodiment performs a self-focusing operation to focus and output the output light Lout in a desired shape of the output light Lout. As shown in parts (a) to (c) of FIG. 5, the number of focus points U of the output light Lout may be one, two, or three or more. When the number of focus points U is two or more, the focus points U may be arranged in a direction intersecting or perpendicular to the thickness direction (i.e., the Z direction) of the light emitting device 1 as shown in part (a) of FIG. 6, or may be distributed on a plane W intersecting or perpendicular to the Z direction. Alternatively, when the number of focus points U is four or more, the focus points U may be distributed three-dimensionally (stereoscopically) as shown in part (b) of FIG. 6. The phase distribution φ(x, y) and the rotation angle distribution α(x, y) are determined according to the distribution of the focus points U of the output light Lout.

[0039] Fig. 7 is a diagram showing a comparison between the light emitting device 1 of this embodiment and a conventional S-iPM laser. As shown in Fig. 7(a), the light emitting device 1 of this embodiment emits the output light Lout while concentrating it. In contrast, as shown in Fig. 7(b), the conventional S-iPM laser 100 emits the output light Lout while diffusing it with a certain spread angle, and forms a light image LM on a certain projection plane PM.

[0040] FIG. 8 is a plan view showing an example in which a refractive index approximately periodic structure is applied in a specific region of the phase modulation layer 15. In the example shown in FIG. 8, an approximately periodic structure (for example, the structure shown in FIG. 3) for emitting a desired optical image is formed inside a square inner region RIN. Meanwhile, a circular modified refractive index region 15b in which the lattice point position of the square lattice coincides with the center of gravity position is arranged in the outer region ROUT surrounding the inner region RIN. The lattice interval a of the virtually set square lattice is the same inside the inner region RIN and in the outer region ROUT. In the case of the structure shown in FIG. 8, light is also distributed in the outer region ROUT, so that it is possible to suppress the generation of high-frequency noise (so-called window function noise) caused by a sudden change in light intensity in the periphery of the inner region RIN. In addition, it is possible to suppress light leakage in a direction perpendicular to the thickness direction, and a reduction in threshold current can be expected. Note that the present invention is not limited to this example, and an approximately periodic structure (for example, the structure shown in FIG. 3) for emitting a desired optical image may be formed in the entire region of the phase modulation layer 15.

[0041] In order to emit the output light Lout while concentrating it, and to obtain a desired distribution of the converging points U, the rotation angle distribution α(x, y) of the modified refractive index area 15b in the phase modulation layer 15 is determined by the following procedure.

[0042] As a first precondition, in an XYZ orthogonal coordinate system defined by a Z axis coinciding with the normal direction and an XY plane coinciding with one surface of the phase modulation layer 15 including the multiple modified refractive index areas 15b, a square-shaped M 1 ×N 1 pieces (M 1 ,N 1 A virtual square lattice composed of unit constituent regions R (R is an integer equal to or greater than 1) is set on the XY plane.

[0043] The second prerequisite is that the coordinates (ξ, η, ζ) in the XYZ Cartesian coordinate system are expressed as the length of the moving radius r and the inclination angle θ from the Z axis, as shown in Figure 9. tilt and the rotation angle θ from the X-axis specified on the XY plane rot and the spherical coordinates (r,θ rot ,θ tilt ) satisfies the relationships shown in the following formulas (1) to (3). rot ,θ tilt ) to coordinates (ξ, η, ζ) in the XYZ Cartesian coordinate system, and the coordinates (ξ, η, ζ) represent a designed light image on a specified plane that is set in the XYZ Cartesian coordinate system, which is real space.

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[0044] The light emitted from the light emitting device 1 is reflected by the incident light at an angle θ tilt and θ rot When the set of bright points is defined as a set of bright points facing in the direction defined by the angle θ tilt and θ rot is the normalized wave number defined by the following equation (4) and corresponds to the X-axis. x The coordinate value kx on the axis and the normalized wave number defined by the following equation (5) which corresponds to the Y axis and is K x K perpendicular to the axis y The normalized wave number is the wave number normalized by taking the wave number 2π / a, which corresponds to the lattice spacing of a virtual square lattice, as 1.0. In this case, x Axes and K y In the wavenumber space defined by the axis, a specific wavenumber range that includes a beam pattern corresponding to a light image is a square-shaped M2 ×N 2 pieces (M 2 ,N 2 The image area FR is composed of the integer M 2 is an integer M 1 Similarly, the integer N 2 is an integer N 1 It is not necessary that the formula (4) and the formula (5) are identical to those shown in FIG. 1. Equations (4) and (5) are disclosed in, for example, Y. Kurosaka et al., "Effects of non-lasing band intwo-dimensional photonic-crystal lasers clarified using omnidirectional bandstructure," Opt. Express 20, 21773-21783 (2012).

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[0045] The third prerequisite is that in wave number space, K x Axial coordinate component kx(0 or more M 2 -1 or less integer) and K y Axial coordinate component ky(0 to N 2 -1 or less) to define the coordinate component x(0 or more M 1 -1 or less) and the Y-axis coordinate component y(0 or more N 1The complex amplitude F(x,y) obtained by performing a two-dimensional inverse discrete Fourier transform on a unitary constituent region R(x,y) on the XY plane specified by x and y (an integer equal to or less than -1) is given by the following equation (6), where j is the imaginary unit. The complex amplitude F(x,y) is defined by the following equation (7), where the amplitude term is A(x,y) and the phase term is φ(x,y). As a fourth prerequisite, the unitary constituent 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 are orthogonal to each other at the lattice point O(x,y) that is the center of the unitary constituent region R(x,y).

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[0046] Under the above first to fourth prerequisites, the phase modulation layer 15 is configured to satisfy the following fifth and sixth conditions. That is, the fifth condition is satisfied when the center of gravity G is disposed away from the lattice point O(x,y) in the unit configuration region R(x,y). The sixth condition is satisfied when the line segment length r from the lattice point O(x,y) to the corresponding center of gravity G is 2 (x,y) is M 1 pieces x N 1 In the state where a common value is set in each of the unit constituent regions R, the angle α(x, y) between the line segment connecting the lattice point O(x, y) and the corresponding center of gravity G and the s-axis is α(x,y)=C×φ(x,y)+B C: proportionality constant, e.g. 180° / π B: Any constant, e.g. 0 This is satisfied by arranging the corresponding modified refractive index area 15b within the unit constituent area R(x, y) so as to satisfy the following relationship.

[0047] Next, the M-point oscillation of the light emitting device 1 will be described. For the M-point oscillation of the light emitting device 1, it is preferable that the lattice spacing a of a virtual square lattice, the emission wavelength λ of the active layer 12, and the equivalent refractive index n of the mode satisfy the condition λ=(√2)n×a. FIG. 10 is a plan view showing a reciprocal lattice space related to a phase modulation layer of a light emitting device performing M-point oscillation. Point P in the figure represents a reciprocal lattice point. Arrow B1 in the figure represents a fundamental reciprocal lattice vector, and arrows K1, K2, K3, and K4 represent four in-plane wave number vectors. Each of the in-plane wave number vectors K1 to K4 has a wave number spread SP due to the rotation angle distribution α(x, y).

[0048] The magnitude of the in-plane wave vectors K1 to K4 (i.e., the magnitude of the standing wave in the in-plane direction) is smaller than the magnitude of the primitive reciprocal lattice vector B1. Therefore, the vector sum of the in-plane wave vectors K1 to K4 and the primitive reciprocal lattice vector B1 is not 0, and the wave number in the in-plane direction cannot become 0 due to diffraction, so diffraction does not occur in the direction perpendicular to the plane (Z-axis direction). If this continues, not only the 0th order light in the direction perpendicular to the plane (Z-axis direction), but also +1st order light and -1st order light in the direction inclined with respect to the Z-axis direction will not be output in the M-point oscillation light emitting device 1.

[0049] In this embodiment, the following device is applied to the phase modulation layer 15 in the M-point oscillation light emitting device 1, so that the 0th order light is not output, and a part of the +1st order light and the -1st order light is output. That is, as shown in Fig. 11, a diffraction vector V1 having a certain magnitude and direction is added to the in-plane wave vectors K1 to K4, so that the magnitude of at least one of the in-plane wave vectors K1 to K4 (the in-plane wave vector K3 in the figure) is made smaller than 2π / λ (λ: wavelength of the light output from the active layer 12). In other words, at least one of the in-plane wave vectors K1 to K4 after the diffraction vector V1 is added is contained within the light line LL, which is a circular region with a radius of 2π / λ.

[0050] In FIG. 11, the in-plane wave vectors K1 to K4 shown by dashed lines represent the wave vectors before the addition of the diffraction vector V1, and the in-plane wave vectors K1 to K4 shown by solid lines represent the wave vectors after the addition of the diffraction vector V1. The light line LL corresponds to the total reflection condition, and a wave vector having a magnitude that falls within the light line LL has a component in the direction perpendicular to the surface (Z-axis direction). In one example, the direction of the diffraction vector V1 is along the Γ-M1 axis or the Γ-M2 axis. The magnitude of the diffraction vector V1 is in the range of 2π / (√2)a-2π / λ to 2π / (√2)a+2π / λ, and in one example, is 2π / (√2)a.

[0051] Next, the magnitude and direction of the diffraction vector V1 for placing at least one of the in-plane wave vectors K1 to K4 within the light line LL will be considered. The following formulas (8) to (11) show the in-plane wave vectors K1 to K4 before the diffraction vector V1 is added.

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[0052] When the diffraction vector V1 is expressed as in the following formula (14), the in-plane wave number vectors K1 to K4 after the diffraction vector V1 is added become the following formulas (15) to (18).

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[0053] In formulas (15) to (18), when it is considered that any of the in-plane wave vectors K1 to K4 falls within the light line LL, the relationship of the following formula (19) holds.

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[0054] The size (radius) of the light line LL is set to 2π / λ for the following reason. FIG. 12 is a diagram for explaining a schematic structure around the light line LL. This diagram shows the boundary between the device and air in the Z direction. The magnitude of the wave vector of light in a vacuum is 2π / λ, but when light propagates through a device medium as shown in FIG. 12, the magnitude of the wave vector Ka in a medium with a refractive index of n is 2πn / λ. At this time, in order for light to propagate through the boundary between the device and air, the wave number components parallel to the boundary must be continuous (law of conservation of wave number).

[0055] In FIG. 12, when the wave vector Ka and the Z axis form an angle θ, the length of the wave vector Kb projected onto the plane (i.e., the in-plane wave vector) is (2πn / λ)sinθ. On the other hand, since the refractive index n of a medium is generally greater than 1, the law of conservation of wave numbers no longer holds when the angle at which the in-plane wave vector Kb in the medium is greater than 2π / λ. At this time, the light is totally reflected and cannot be extracted to the air side. The magnitude of the wave vector corresponding to this total reflection condition is the magnitude of the light line LL, i.e., 2π / λ.

[0056] As an example of a specific method of adding a diffraction vector V1 to the in-plane wave vectors K1 to K4, a phase distribution φ according to a desired output light shape is 1 For (x,y), the phase distribution φ is independent of the desired output beam shape. 2 In this case, the phase distribution φ(x, y) of the phase modulation layer 15 is expressed as φ(x, y)=φ 1 (x,y)+φ 2 It is expressed as (x,y). 1 As mentioned above, (x, y) corresponds to the phase of the complex amplitude when the desired shape of the emitted light is Fourier transformed. Also, φ 2 (x, y) is the phase distribution for adding the diffraction vector V1 that satisfies the above equation (19).

[0057] Figure 13 shows the phase distribution φ 2 FIG. 1 is a diagram conceptually illustrating an example of (x, y). In the example of the diagram, a first phase value φ A and a first phase value φ A A second phase value φ different from B In one example, the phase values ​​φ A is 0 (rad), and the phase value φ B In this case, the first phase value φ is A and a second phase value φ Band change by π. Such an arrangement of phase values ​​can suitably realize a diffraction vector V1 along the Γ-M1 axis or the Γ-M2 axis. In the case of a checkerboard arrangement, V1=(±π / a, ±π / a), and the diffraction vector V1 and any one of the in-plane wave vectors K1 to K4 in FIG. 11 are exactly offset. Therefore, the axis of symmetry between the +1st order light and the -1st order light coincides with the Z direction, that is, the direction perpendicular to the in-plane direction of the phase modulation layer 15. In general, the angular distribution θ of the diffraction vector V 2 (x, y) is expressed as the inner product of the diffraction vector V(Vx, Vy) and the position vector r(x, y), and is given by the following equation. θ 2 (x,y) = V r = Vx x + Vy y Therefore, when V=V1, the phase value is 0 and π when the position vector is r(xa, ya) (x and y are both integers). On the other hand, as described above, the diffraction vector V1 may be shifted from (±π / a, ±π / a) as long as at least one of the in-plane wave vectors K1 to K4 is within the range of the light line LL.

[0058] In this embodiment, when the wave number spread based on the angular spread of the emitted light is included in a circle of radius Δk centered on a certain point in wave number space, it can be simply considered as follows. By adding the diffraction vector V1 to the in-plane wave number vectors K1 to K4 in four directions, the magnitude of at least one of the in-plane wave number vectors K1 to K4 in four directions is made smaller than 2π / λ (light line LL). This can be considered as making the magnitude of at least one of the in-plane wave number vectors K1 to K4 in four directions smaller than the value {(2π / λ)-Δk} obtained by subtracting the wave number spread Δk from 2π / λ by adding the diffraction vector V1 to the in-plane wave number vectors K1 to K4 in four directions.

[0059] FIG. 14 is a diagram conceptually illustrating the above-mentioned idea. As shown in the figure, when a diffraction vector V1 is added to the in-plane wave vectors K1 to K4 excluding the wave number spread Δk, the magnitude of at least one of the in-plane wave vectors K1 to K4 becomes smaller than {(2π / λ)-Δk}. In FIG. 14, the region LL2 is a circular region with a radius of {(2π / λ)-Δk}. In FIG. 14, the in-plane wave vectors K1 to K4 shown by the dashed lines represent the state before the diffraction vector V1 is added, and the in-plane wave vectors K1 to K4 shown by the solid lines represent the state after the diffraction vector V1 is added. The region LL2 corresponds to the total reflection condition considering the wave number spread Δk, and the wave vectors whose magnitude falls within the region LL2 will also propagate in the direction perpendicular to the surface (Z-axis direction).

[0060] In this embodiment, the magnitude and direction of the diffraction vector V1 for placing at least one of the in-plane wave vectors K1 to K4 within the region LL2 will be described. The following formulas (20) to (23) show the in-plane wave vectors K1 to K4 before the diffraction vector V1 is added.

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[0061] Here, when the diffraction vector V1 is expressed as in the above-mentioned formula (14), the in-plane wave number vectors K1 to K4 after the diffraction vector V1 is added are expressed by the following formulas (24) to (27).

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[0062] In formulas (24) to (27), if it is considered that any of the in-plane wave vectors K1 to K4 falls within region LL2, the relationship of the following formula (28) is established. That is, by adding a diffraction vector V1 that satisfies formula (28), any of the in-plane wave vectors K1 to K4 excluding the wave number spread Δk falls within region LL2. Even in such a case, it is possible to output a part of the +1st order light and the -1st order light without outputting the 0th order light.

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[0063] Fig. 15 is a plan view showing another embodiment of the phase modulation layer 15. Fig. 16 is a diagram showing the arrangement of the modified refractive index areas 15b in the phase modulation layer 15 shown in Fig. 15. As shown in Figs. 15 and 16, the center of gravity G of each modified refractive index area 15b of the phase modulation layer 15 may be arranged on a straight line D. The straight line D passes through a lattice point O corresponding to each unit constituent area R and is inclined with respect to each side of the square lattice. In other words, the straight line D is inclined with respect to both the X-axis and the Y-axis. The inclination angle of the straight line D with respect to one side (X-axis) of the square lattice is β.

[0064] In this case, the tilt angle β is constant within the phase modulation layer 15. The tilt angle β satisfies 0°<β<90°, and in one example, β=45°. Alternatively, the tilt angle β satisfies 180°<β<270°, and in one example, β=225°. When the tilt angle β satisfies 0°<β<90° or 180°<β<270°, the straight line D extends from the first quadrant to the third quadrant of the coordinate plane defined by the X-axis and the Y-axis. The tilt angle β satisfies 90°<β<180°, and in one example, β=135°. Alternatively, the tilt angle β satisfies 270°<β<360°, and in one example, β=315°. When the inclination angle β satisfies 90°<β<180° or 270°<β<360°, the straight line D extends from the second quadrant to the fourth quadrant of the coordinate plane defined by the X-axis and the Y-axis. Thus, the inclination angle β is an angle excluding 0°, 90°, 180°, and 270°.

[0065] Here, the distance between the lattice point O and the center of gravity G is r(x,y). x is the position of the x-th lattice point on the X-axis, and y is the position of the y-th lattice point on the Y-axis. When the distance r(x,y) is a positive value, the center of gravity G is located in the first quadrant (or the second quadrant). When the distance r(x,y) is a negative value, the center of gravity G is located in the third quadrant (or the fourth quadrant). When the distance r(x,y) is 0, the lattice point O and the center of gravity G coincide with each other. The tilt angles are preferably 45°, 135°, 225°, and 275°. At these tilt angles, only two of the four wave vectors (for example, in-plane wave vectors (±π / a, ±π / a)) that form the standing wave at point M are phase modulated, and the other two are not phase modulated, so that a stable standing wave can be formed.

[0066] The distance r(x, y) between the center of gravity G of each modified refractive index area and the lattice point O corresponding to each unit constituent area R is set individually for each modified refractive index area 15b according to the phase distribution φ(x, y) corresponding to the desired shape of the emitted light. In the present disclosure, such an arrangement form of the center of gravity G is referred to as the second form. The phase distribution φ(x, y) and the distance distribution r(x, y) have specific values ​​for each position determined by the values ​​of x and y, but are not necessarily expressed by a specific function. The distribution of the distance r(x, y) is determined by extracting the phase distribution φ(x, y) from the complex amplitude distribution obtained by performing an inverse Fourier transform on the desired shape of the emitted light.

[0067] That is, the phase φ(x,y) at a certain coordinate (x,y) is φ 0 If so, set the distance r(x,y) to 0 and the phase φ(x,y) to π+φ 0 If so, the distance r(x,y) is set to the maximum value R 0 and the phase φ(x,y) is set to -π+φ 0 If so, set the distance r(x,y) to the minimum value -R 0 For the intermediate phase φ(x,y), we set r(x,y)={φ(x,y)-φ 0}×R 0 Set the distance r(x,y) so that / π. The initial phase φ 0 can be set arbitrarily.

[0068] If the lattice spacing of a virtual square lattice is a, the maximum value of r(x,y) is R 0 is within the range of the following formula (29), for example: When determining the complex amplitude distribution from a desired optical image, it is possible to improve the reproducibility of the beam pattern by applying an iterative algorithm such as the GS method, which is commonly used in calculations for generating holograms.

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[0069] In this second embodiment, a desired light emission shape (number and positions of light-collecting points, etc.) can be obtained by determining the distribution of distance r(x, y) of the modified refractive index area 15b of the phase modulation layer 15. Under the same first to fourth preconditions as those of the first embodiment, the phase modulation layer 15 is configured to satisfy the following condition. That is, the distance r(x, y) from the lattice point O(x, y) to the center of gravity G of the corresponding modified refractive index area 15b is: r(x,y)=C×(φ(x,y)-φ 0 ) C: Proportional constant, e.g. R 0 / π φ 0 : Any constant, e.g. 0 The corresponding modified refractive index areas 15b are arranged in the unit constituent area R(x, y) so as to satisfy the following relationship. When it is desired to obtain a desired light output shape, the light output shape may be subjected to an inverse Fourier transform, and a distribution of distances r(x, y) according to the phase φ(x, y) of the complex amplitude may be provided to the multiple modified refractive index areas 15b. The phase φ(x, y) and the distances r(x, y) may be proportional to each other.

[0070] In the second embodiment, similarly to the first embodiment, the lattice spacing a of the virtual square lattice and the emission wavelength λ of the active layer 12 satisfy the condition for M-point oscillation. Furthermore, when considering the reciprocal lattice space in the phase modulation layer 15, the magnitude of at least one of the in-plane wave vectors K1 to K4 in four directions, each of which includes the wave number spread due to the distribution of the distance r(x, y), is smaller than 2π / λ, i.e., the light line LL.

[0071] In the second embodiment, the light emitting device oscillating at point M is designed as follows to output a part of +1st order light and -1st order light without outputting the 0th order light into the light line LL. Specifically, as shown in FIG. 11, a diffraction vector V1 having a certain magnitude and direction is added to the in-plane wave vectors K1 to K4, so that the magnitude of at least one of the in-plane wave vectors K1 to K4 is made smaller than 2π / λ. That is, at least one of the in-plane wave vectors K1 to K4 after the diffraction vector V1 is added is contained within the light line LL, which is a circular region with a radius of 2π / λ. By adding the diffraction vector V1 that satisfies the above-mentioned formula (19), one of the in-plane wave vectors K1 to K4 is contained within the light line LL, and a part of the +1st order light and -1st order light is output.

[0072] 14, by adding a diffraction vector V1 to the in-plane wave vectors K1 to K4 in four directions minus the wave number spread Δk (i.e., the in-plane wave vectors in four directions in an M-point oscillation square lattice PCSEL), the magnitude of at least one of the in-plane wave vectors K1 to K4 in four directions may be made smaller than the value obtained by subtracting the wave number spread Δk from 2π / λ {(2π / λ)-Δk}. That is, by adding the diffraction vector V1 that satisfies the above-mentioned formula (28), any one of the in-plane wave vectors K1 to K4 falls within the region LL2, and a part of the +1st order light and the -1st order light is output.

[0073] Here, the design of the phase modulation layer 15 for condensing and emitting light from the light emitting device 1 will be described in detail.

[0074] [Single focus type (A)] First, the design of the phase modulation layer 15 for forming a single light-converging point U by the light-emitting device 1 itself will be described. In this case, the phase distribution φ 1 (x, y) is a phase distribution including a lens element for converging the emitted light, i.e., a lens phase distribution φ L Set (x, y). Figure 17 shows the lens phase distribution φ L1 is a diagram showing an example of (x, y). In the figure, the magnitude of the phase is expressed by the shade of color, and the darker the color, the closer it is to 0 (rad), and the lighter the color, the closer it is to 2π (rad). In this example, the phase becomes smaller as it moves away from the center of the phase modulation layer 15, and this lens phase distribution φ L (x, y) can act as a convex lens element for the emitted light. Note that this lens phase distribution φ L (x, y) are expressed by the formula (30). Here, λ is the wavelength in the medium in the phase modulation layer 15, (x, y) is the lattice point position in the plane, and f is the focal length. The sign of the focal length f may be either + or -. When the sign of the focal length f is +, it becomes a concave lens, and when it is -, it becomes a convex lens.

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[0075] FIG. 18 shows the lens phase distribution φ L FIG. 1 is a partially enlarged view of the lens phase distribution φ(x,y). L When (x, y) is viewed locally, a first phase value and a second phase value different from the first phase value are arranged in a checkerboard pattern at first glance, as in FIG. 13. For example, in the case of such a lens phase distribution φ L The above-mentioned diffraction vector V1 can be added to the in-plane wave vectors K1 to K4 by (x, y). The phase value of each portion of the phase modulation layer 15 is obtained as the sum of the average values ​​of the first and second phase values ​​included in each portion.

[0076] 19 and 20 are diagrams showing the results of an experiment in which a light-emitting device 1 according to this embodiment was fabricated as a prototype, and a near-field image was captured while moving the objective lens in the Z direction. In this experiment, the movement interval of the objective lens was set to 100 μm, and the Z-axis coordinate of the light emission surface was set to z=0 mm. The light emission wavelength λ of the prototype light-emitting device 1 was set to 940 nm, the lattice interval a was set to 202 nm, the length r of the vector connecting the lattice point O and the center of gravity G was set to 0.08a, and the focal length f was set to 0.32 mm. FIG. 19 shows the lens phase distribution φ L(x, y) is a convex lens, and Fig. 20 shows the lens phase distribution φ L This shows the case where (x, y) is a concave lens. For comparison, Fig. 21 shows the result of capturing a near-field image of a normal light-emitting device (LED) that does not have a phase modulation layer 15. In Figs. 19 to 21, the light intensity is represented by the shade of color, and the lighter the color, the greater the light intensity.

[0077] 19 and 20, it can be seen that in the light emitting device 1 of this embodiment, the emitted light converges at a position 0.3 mm from the light emitting surface. Also, as shown in Fig. 21, in a normal light emitting device, the near-field pattern is clear at the light emitting surface (z = 0 mm), and the near-field pattern becomes unclear as the distance from the light emitting surface increases. Thus, the light emitting device 1 of this embodiment can emit light while concentrating it.

[0078] Furthermore, according to this experiment, the emitted light was converged even at a position −0.3 mm from the light exit surface (i.e., on the opposite side to the light exit surface of the light-emitting device 1). The reason for this is believed to be as follows. That is, as shown in FIG. 22, +1st order light La and −1st order light Lb are emitted from the phase modulation layer 15 of the light-emitting device 1 in directions symmetrical to each other. Lens phase distribution φ L When (x, y) is a convex lens (FIG. 19), the +1st-order light La converges at a focusing point U at a certain distance (0.3 mm in the example of FIG. 19) from the phase modulation layer 15, and the -1st-order light Lb converges as a virtual image at a focusing point UD at a certain distance (-0.3 mm in the example of FIG. 19) on the opposite side from the phase modulation layer 15. Conversely, the lens phase distribution φ L When (x, y) is a concave lens (Figure 20), the -1st order light Lb converges at a focusing point U at a certain distance (0.3 mm in the example of Figure 20) from the phase modulation layer 15, and the +1st order light La converges at a focusing point UD at a certain distance (-0.3 mm in the example of Figure 20) on the opposite side from the phase modulation layer 15.

[0079] [Single focal point type (B)] Next, another design of the phase modulation layer 15 for forming a single light-converging point U by a single light-emitting device 1 itself will be described. As described above, the checkered phase distribution φ 2 According to (x, y), the diffraction vector V1 becomes V1=(±π / a, ±π / a), and the diffraction vector V1 exactly cancels out any one of the in-plane wave vectors K1 to K4 in Fig. 10. Therefore, any one of the in-plane wave vectors K1 to K4 becomes a zero vector, and the axis of symmetry between the +1st order light and the -1st order light coincides with the Z direction, that is, the direction perpendicular to the in-plane direction of the phase modulation layer 15.

[0080] In one design of the single-focus type, the above-mentioned diffraction vector V1 is changed so that the lengths of all of the in-plane wave vectors K1 to K4 are greater than 0 (i.e., the in-plane wave vectors K1 to K4 are non-zero vectors), and the symmetry axis between the +1st order light and the -1st order light is tilted from the Z direction. In other words, the center position of the optical image output from the light-emitting device 1 is separated from the axis line that passes through the center of the light-emitting surface of the light-emitting device 1 and extends in the Z direction. Such a diffraction vector V1 is obtained by adding a non-zero vector (dVx, dVy) to the above-mentioned diffraction vector V1=(±π / a, ±π / a). That is, the diffraction vector V1 is set to V1=±(π / a)(1+dVx, 1+dVy). In this case, the lens phase distribution φ L The phase distribution φ(x,y) containing (x,y) is expressed as follows:

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[0081] The component of the phase distribution corresponding to the non-zero vector (dVx, dVy) is the lens phase distribution φ L Together with (x, y), this constitutes an element for focusing the emitted light to one focusing point U in the phase distribution φ(x, y). Even if the axis of symmetry between the +1st order light and the -1st order light is inclined from the Z direction, both the +1st order light and the -1st order light form the focusing point U at the same position on the light emission surface side of the light emitting device 1. Therefore, according to this design, one focusing point U can be suitably formed.

[0082] FIG. 23 shows the lens phase distribution φ L This is a diagram showing an example of a phase distribution φ(x,y) including components corresponding to (x,y) and non-zero vectors (dVx,dVy). In this diagram, the magnitude of the phase is expressed by the shade of color, with the darker the color, the closer to 0 (rad), and the lighter the color, the closer to 2π (rad).

[0083] [Multiple focal points] Next, a description will be given of one design of the phase modulation layer 15 for forming a plurality of light-converging points U by a single light-emitting device 1 itself. In this design, a hologram phase distribution φ H (x, y) and the lens phase distribution φ for converging the output light Lout L (x, y) are combined. The combined phase distribution is then used as an element for focusing the emitted light to at least two focusing points U to obtain a phase distribution φ 1 (x,y). Then, this phase distribution φ 1 (x,y) and the phase distribution φ for the diffraction vector V1 2 The sum of (x, y) is calculated to obtain the final phase distribution φ(x, y). Phase distribution φ 1 (x, y) is the hologram phase distribution φ H (x,y) and lens phase distribution φ L The hologram phase distribution φ may be composed of only a phase distribution obtained by synthesizing (x, y) and (x, y). H (x, y) corresponds to the first phase distribution in this disclosure, and the lens phase distribution φ L (x, y) corresponds to the second phase distribution in this disclosure.

[0084] Hologram phase distribution φ H (x, y) forms the at least two points at positions away from an axis that passes through the center of the light emitting surface of the light emitting device 1 and extends in the Z direction. In other words, the hologram phase distribution φ H (x, y) is a phase distribution in which in-plane wave vectors K1 to K4 are non-zero vectors, and forms a hologram for emitting light toward two or more different points.

[0085] When at least two focal points U are located on the same imaginary plane perpendicular to the z-axis, the hologram phase distribution φ H (x,y) and lens phase distribution φ L As an example of a method for synthesizing (x, y) and the hologram phase distribution φ H (x,y) phase value and lens phase distribution φ L The sum of the phase value of (x,y) and φ H (x,y)+φ L In addition, when at least two focal points U are located on multiple imaginary planes that are perpendicular to the z axis and have different z coordinates, the hologram phase distribution φ H (x,y) and lens phase distribution φ L As a method for synthesizing (x, y), for example, there are the following methods. In each of the following methods, the hologram phase distribution φ H (x,y) phase value and lens phase distribution φ L The sum of the phase value of (x,y) and φ H (x,y)+φ L (x,y) is the synthetic phase distribution φs 1 (x,y)~φs n (x,y) (n is the number of imaginary planes) is first calculated for each imaginary plane. Then, the composite phase distribution φs 1 (x,y)~φs n (x, y) are mutually synthesized. The synthesized phase distribution is used as an element for focusing the output light to at least two focusing points U, and the phase distribution φ 1 Include in (x,y).

[0086] One is the synthetic phase distribution φs 1 (x,y)~φs n This method divides each of (x, y) into a real part and an imaginary part, and performs phase synthesis on each of the real part and the imaginary part (hereinafter referred to as the first method). A conceptual diagram of this method is shown in Figure 24 (note that Figure 24 shows the case where n=2). First, the synthetic phase distribution φs 1 (x,y)~φs n Each of (x, y) is divided into a real part and an imaginary part (steps B1 and B2 in the figure). exp(j φs 1 )=cos(φs 1 )+j·sin(φs 1 ) exp(j φs 2 )=cos(φs 2 )+j·sin(φs 2 ) · · · exp(j φs n )=cos(φs n )+j·sin(φs n ) Next, the synthetic phase distribution φs 1 (x,y)~φs n The real parts and imaginary parts of (x, y) are added together as shown below (processes B3 and B4 in the figure). Real part Re=cos(φs 1 )+cos(φs 2 ) + … + cos(φs n ) Imaginary part Im=sin(φs 1 ) + sin(φs 2 ) + ... + sin(φs n ) Then, these real part Re and imaginary part Im are written in polar form as follows (process B5 in the figure). Re+j Im=A exp(j φ 1 )(A: amplitude, φ: declination angle) From the above calculations, the synthetic phase φ at each coordinate (x, y) 1 , i.e., the phase distribution φ for focusing at least two focusing points U 1 (x, y) is obtained (process B6 in the figure).

[0087] The other is the synthetic phase distribution φs 1 (x,y)~φs n The average value of (x,y) is the phase distribution φ 1 (x, y) (hereinafter referred to as the second method). That is, the phase distribution φ 1 (x, y) is expressed as (φs 1 +φs 2 +…+φsn ) / n.

[0088] The other one is each synthetic phase distribution φs 1 (x,y)~φs n This is a method in which phase values ​​are randomly selected from (x, y) in a two-dimensional manner and the selected phase values ​​are superimposed (hereinafter referred to as the third method). In this method, the synthetic phase distribution φs 1 (x,y)~φs n Select a phase value from only one of (x, y) and combine two or more synthetic phase distributions φs 1 (x,y)~φs n The phase values ​​of (x, y) are not overlapped. Figure 25 shows an example of a random pattern used in this method. Note that in Figure 25, n=2 is assumed. Figure 25(a) shows the composite phase distribution φs 1 (x,y) and FIG. 25(b) shows the random pattern 50A applied to (x,y) and the synthetic phase distribution φs 2 1 shows a random pattern 50B applied to (x, y). These random patterns 50A and 50B have a plurality of regions 51 arranged two-dimensionally along the x and y directions, and these regions 51 correspond one-to-one to each phase value of the phase distribution. In the figure, the plurality of regions 51 are colored black and white, and here, the white regions are regions 52 where a phase value is selected (hereinafter, selected regions), and the black regions are regions 53 where a phase value is not selected (hereinafter, non-selected regions). That is, the composite phase distribution φs 1 The phase value of the coordinates (x, y) corresponding to the selected region 52 of the random pattern 50A is selected from (x, y), and the composite phase distribution φs 2From among (x, y), a phase value of coordinates (x, y) corresponding to selected region 52 in random pattern 50B is selected. Comparing random pattern 50A and random pattern 50B, selected regions 52 in random pattern 50A and selected regions 52 in random pattern 50B are distributed complementarily. That is, selected region 52 in random pattern 50A is always non-selected region 53 in random pattern 50B, and non-selected region 53 in random pattern 50A is always selected region 52 in random pattern 50B. Selected regions 52 are distributed two-dimensionally and randomly in the xy plane. The number of selected regions 52 in random pattern 50A (i.e., composite phase distribution φs 1 (x, y)) and the number of selected regions 52 in the random pattern 50B (i.e., the number of phase values ​​selected from the synthetic phase distribution φs 2 The number of phase values ​​selected from (x, y) may be equal to each other or may be slightly different.

[0089] A method for creating the random patterns 50A and 50B described above may be, for example, to assign a value to each region from random numbers between 0 and 1, and define the region where the value is equal to or greater than 0 and less than 1 / 2 as the selection region 52 of the random pattern 50A, the region where the value is equal to or greater than 1 / 2 and less than 1 as the selection region 52 of the random pattern 50B, etc. Note that the random number distribution may be created using, for example, the Rand function of MATLAB (registered trademark), which is a numerical calculation software.

[0090] In FIG. 25, the case of n=2 is assumed, but n may be 3 or more. When n=3, the composite phase distribution φs 1 A random pattern selection area 52 corresponding to (x, y) and a synthetic phase distribution φs 2 A random pattern selection area 52 corresponding to (x, y) and a synthetic phase distribution φs 3 The random pattern selection area 52 corresponding to (x, y) is distributed complementarily. That is, the composite phase distribution φs 1 The selected area 52 in the random pattern corresponding to (x, y) is a region of another synthetic phase distribution φs 2 (x, y) and φs3 In each random pattern corresponding to (x, y), there is always a non-selected region 53, and the synthetic phase distribution φs 2 The selected area 52 in the random pattern corresponding to (x, y) is a region of another synthetic phase distribution φs 1 (x, y) and φs 3 In each random pattern corresponding to (x, y), there is always a non-selected region 53, and the synthetic phase distribution φs 3 The selected area 52 in the random pattern corresponding to (x, y) is a region of another synthetic phase distribution φs 1 (x, y) and φs 2 In each random pattern corresponding to (x, y), it is always a non-selected region 53. As a method for creating such a random pattern, for example, a value is assigned to each region from a random number between 0 and 1, and the region where the value is equal to or greater than 0 and less than 1 / 3 is selected as a synthetic phase distribution φs 1 The random pattern selection area 52 corresponding to (x, y) is defined as the area that is 1 / 3 or more and less than 2 / 3 of the area, and the synthetic phase distribution φs 2 The random pattern selection area 52 corresponding to (x, y) is defined as the area between 2 / 3 and 1 inclusive, and the synthetic phase distribution φs 3 It is advisable to define it as a selection area 52 of a random pattern corresponding to (x, y), etc. Even if n is 4 or more, a random pattern can be created by a method similar to the above method.

[0091] According to each of the above methods, the hologram phase distribution φ H Since the +1st order light can be emitted toward at least two points using (x, y), at least two light-concentration points U can be formed using only the +1st order light.

[0092] Here, a two-point light-collecting type light-emitting device 1 was fabricated, and the results of an experiment in which a near-field image was captured while moving the objective lens in the Z direction are shown. FIG. 26 is a diagram showing the position of the light-collecting point U. In this experiment, as shown in FIG. 26(a), one light-collecting point U was formed at a position where the distance z from the light-emitting surface was 1 mm and a predetermined distance in the +Y direction from an axis line passing through the center of the light-emitting surface of the light-emitting device 1 and extending in the Z direction. Also, as shown in FIG. 26(b), another light-collecting point U was formed at a position where the distance z from the light-emitting surface was 2 mm and a predetermined distance in the -Y direction from an axis line passing through the center of the light-emitting surface of the light-emitting device 1 and extending in the Z direction. In this experiment, the moving interval of the objective lens was set to 100 μm to 1000 μm, and the Z-axis coordinate of the light-emitting surface was set to z=0 mm. The emission wavelength λ, lattice spacing a, and length r of the vector connecting the lattice point O and the center of gravity G of the prototype light emitting device 1 were set to the same values ​​as those in FIGS.

[0093] 27 to 29 show near-field patterns of the light-emitting device 1 produced in this experiment. FIG. 27 shows a near-field pattern when the light-emitting device 1 was produced by the second method described above. FIG. 28 shows a near-field pattern when the light-emitting device 1 was produced by the first method described above (see FIG. 24). FIG. 29 shows a near-field pattern when the light-emitting device 1 was produced by the third method described above. In these FIGS. 27 to 29, the light intensity is represented by the shade of color, and the lighter the color, the greater the light intensity.

[0094] 27 to 29, it can be seen that the focal point U shown in FIG. 26 appears at each position of z=1 mm and z=2 mm in both methods. However, referring to FIG. 27, a substantially square noise is confirmed near the center. The magnitude of this substantially square noise does not change significantly even if the defocus distance z is changed in the range shown in FIG. 27. Therefore, it is considered to be a defocused image that is a near-field image that is not affected by the focusing action due to the lens phase. The spread of the defocused image shown in FIG. 27 is smaller than the spread of the defocused image of the light-emitting element (LED) shown in FIG. 21. This is because the laser oscillates in an area relatively large with respect to the wavelength. Therefore, in the defocused image shown in FIG. 27, the diffraction spread is small, and a sharp bright spot was seen in the plane perpendicular direction. Therefore, the substantially square noise is considered to be light diffracted in the plane perpendicular direction by the action of the diffraction vector V1 of the standing wave resonating in the plane, that is, a light component that has not been subjected to the phase modulation action due to the composite phase of the hologram phase and the lens phase. Therefore, it is more preferable to fabricate the light emitting device 1 by either the first method or the third method.

[0095] Next, another light emitting device 1 of the multiple light condensing type was fabricated, and the results of an experiment in which a near-field image was captured while moving the objective lens in the Z direction are shown. FIG. 30 is a diagram showing the position of the light condensing point U. In this experiment, as shown in FIG. 30(a), a number of light condensing points U were arranged along the X direction at a distance z of 1 mm from the light emitting surface, and across an axis line extending in the Z direction, passing through the center of the light emitting surface of the light emitting device 1. Also, as shown in FIG. 30(b), another number of light condensing points U were arranged along the Y direction at a distance z of 2 mm from the light emitting surface, and across an axis line extending in the Z direction, passing through the center of the light emitting surface of the light emitting device 1. In this experiment, the movement interval of the objective lens was set to 250 μm, and the Z-axis coordinate of the light emitting surface was set to z=0 mm. Also, the emission wavelength λ, lattice interval a, and length r of the vector connecting the lattice point O and the center of gravity G of the fabricated light emitting device 1 were set to the same as those in FIG. 19 to FIG. 21.

[0096] 31 to 33 show near-field patterns of the light-emitting device 1 produced in this experiment. FIG. 31 shows a near-field pattern when the light-emitting device 1 is produced by the second method described above. FIG. 32 shows a near-field pattern when the light-emitting device 1 is produced by the first method described above (see FIG. 24). FIG. 33 shows a near-field pattern when the light-emitting device 1 is produced by the third method described above. Note that in these FIGS. 31 to 33 as well, the light intensity is represented by shades of color, with the lighter the color, the greater the light intensity.

[0097] 31 to 33, it can be seen that in all the methods, the light-converging point U shown in FIG. 30 appears at the positions z=1 mm and z=2 mm. However, in FIG. 31, a substantially square noise is observed near the center. This substantially square noise is considered to be caused by the same effect as the substantially square noise shown in FIG. 27 described above. Therefore, it is more preferable to fabricate the light-emitting device 1 by either the first method or the third method.

[0098] In each of the above experiments, light-converging points appear at positions −1.0 mm and −2.0 mm from the light exit surface, similar to the above-mentioned Figures 19 to 21. This is because +1-order light (or −1-order light) as a real image converges in the region z>0, whereas −1-order light (or +1-order light) as a virtual image converges in the region z<0.

[0099] The effect obtained by the light emitting device 1 of the present embodiment described above will be described. In this light emitting device 1, the centers of gravity G of the multiple modified refractive index areas 15b are arranged away from the corresponding lattice points O of a virtual square lattice, and have individual rotation angles α around the lattice points O according to a predetermined phase distribution φ(x, y), or are arranged on a straight line D that passes through the lattice points O of the virtual square lattice and is inclined with respect to the square lattice, and the distance r between the centers of gravity G of each modified refractive index area 15b and the lattice points O corresponding to each modified refractive index area 15b is individually set according to the predetermined phase distribution φ(x, y). With such a structure, an optical image of any shape can be generated as an S-iPM laser.

[0100] In addition, in this light-emitting device 1, the lattice spacing a of the virtual square lattice and the emission wavelength λ of the active layer 12 satisfy the condition for M-point oscillation. As described above, normally, in the standing wave state of M-point oscillation, the light propagating in the phase modulation layer 15 is totally reflected, and the output of both the signal light (for example, at least one of +1st order light and -1st order light) and the 0th order light is suppressed. However, in this light-emitting device 1, in the reciprocal lattice space of the phase modulation layer 15, the standing wave is phase-modulated by the phase distribution φ(x, y), and forms four-directional in-plane wave vectors K1 to K4 each including a wave number spread corresponding to the angular spread of the emitted light. And, the magnitude of at least one of these in-plane wave vectors K1 to K4 is 2π / λ, that is, smaller than the light line LL. In the S-iPM laser, such in-plane wave vectors K1 to K4 can be adjusted by devising the arrangement of each modified refractive index area 15b. When the magnitude of at least one in-plane wave vector is smaller than 2π / λ, the in-plane wave vector has a component in the thickness direction (Z direction) of the phase modulation layer 15 and does not undergo total reflection at the interface with air. As a result, a part of the signal light is output from the phase modulation layer 15. However, when the condition of M-point oscillation is satisfied, the zero-order light is totally reflected at the interface with air and is not output from the phase modulation layer 15 into the light line LL. That is, according to the light-emitting device 1 of this embodiment, the zero-order light included in the output of the S-iPM laser can be removed from the light line LL and only the signal light can be output.

[0101] In addition, in the light-emitting device 1, the phase distribution φ(x, y) includes an element for concentrating the output light Lout. This allows the light-emitting device 1 to output light while concentrating it. As described above, the light-emitting device 1 suppresses the output of zero-order light that does not contribute to concentrating light, so that it is possible to output only signal light that can contribute to concentrating light. In this way, the light-emitting device 1 allows light to be concentrated by itself, so that the number of optical components for concentrating light can be reduced, and the light source device can be made smaller.

[0102] The element for focusing the output light Lout included in the phase distribution φ(x, y) may be an element for focusing the output light Lout at at least two focusing points U. As described above, according to the light-emitting device 1, by appropriately designing the element for focusing included in the phase distribution φ(x, y), it is also possible to focus the output light Lout from one light-emitting device 1 at least two focusing points U. Therefore, the light source device can be further miniaturized.

[0103] The element for focusing the output light Lout included in the phase distribution φ(x,y) may be an element for making the magnitudes of the in-plane wave vectors K1 to K4 in the four directions all greater than 0 (i.e., making the in-plane wave vectors K1 to K4 non-zero vectors). For example, the output light Lout can be focused to a single focusing point U by such an element.

[0104] The phase distribution φ(x, y) is a hologram phase distribution φ for emitting the output light Lout toward at least two points. H (x, y) and the lens phase distribution φ for converging the output light Lout L The phase distribution obtained by combining (x, y) and (x, y) may be included as the above element. For example, the output light Lout can be focused to at least two focusing points U by using such an element.

[0105] 6(a), at least two light-concentration points U may be arranged in a direction intersecting the thickness direction (Z direction). In this case, the light-emitting device 1 can be used for purposes such as causing light from each light-concentration point U to interfere with each other.

[0106] 6(b), the elements of the phase distribution φ(x, y) are elements for focusing the output light Lout onto at least four focusing points U, and the at least four focusing points U may be distributed three-dimensionally. In this case, the light-emitting device 1 can be used for purposes such as creating a three-dimensional (stereoscopic) optical image.

[0107] Second embodiment FIG. 34 is a schematic diagram showing the configuration of a three-dimensional measurement system 101 according to the second embodiment. As shown in the figure, the three-dimensional measurement system 101 includes a light source device 102, a plurality of (for example, a pair of) image capturing units 103, and a measurement unit 104. The light source device 102 includes one or a plurality of light emitting devices 1 according to the first embodiment. Measurement light 105 emitted from the light source device 102 is irradiated onto a certain area on the surface of the measurement object SA placed on a stage 106. The stage 106 may be a scanning stage capable of scanning in two-dimensional or three-dimensional directions. Note that when the irradiation range of the measurement light 105 is sufficiently wide relative to the measurement range of the measurement object SA, the arrangement of the stage 106 may be omitted.

[0108] FIG. 35 is a diagram showing a light source device 102A as an example of the configuration of the light source device 102. As shown in the figure, the light source device 102A includes one light emitting device 1A and an optical system 110. The optical system 110 is optically coupled to the light emission surface of the light emitting device 1A. In one example, the optical axis of the optical system 110 coincides with an axis AX1 that passes through the center of the light emission surface of the light emitting device 1A and extends along the Z direction (see FIG. 1). The optical system 110 is a lens having a light collecting effect, such as a convex lens.

[0109] The light emitting device 1A is the light emitting device 1 of the first embodiment, and forms two light focusing points U1 and U2 located between the light emitting device 1 and the optical system 110. That is, the element for focusing the emitted light, which is included in the phase distribution φ(x, y) of the phase modulation layer 15 of the light emitting device 1A, has the multiple light focusing point type configuration described in the first embodiment. This element focuses the emitted light Lout1 output from the light emitting device 1A at the light focusing point U1, and focuses the emitted light Lout2 output from the light emitting device 1A at the light focusing point U2. The light focusing points U1 and U2 are formed side by side in a direction intersecting (for example, perpendicular to) the axis AX1. In addition, the distance from the axis AX1 to the light focusing point U1 and the distance from the axis AX1 to the light focusing point U2 are equal to each other. In other words, the light focusing points U1 and U2 are formed at positions symmetrical with respect to the axis AX1. The output light Lout1 corresponds to the first output light in this disclosure, and the output light Lout2 corresponds to the second output light in this disclosure. The light-concentration point U1 corresponds to the first light-concentration point in this disclosure, and the light-concentration point U2 corresponds to the second light-concentration point in this disclosure.

[0110] 36 is a diagram illustrating a light source device 102B as another example of the configuration of the light source device 102. As shown in the figure, the light source device 102B includes two light emitting devices 1B and 1C and an optical system 110. The normals of the light emitting surfaces of the light emitting devices 1B and 1C are parallel to each other and are located in a common plane. The light emitting device 1B corresponds to the first light emitting device in this disclosure, and the light emitting device 1C corresponds to the second light emitting device in this disclosure.

[0111] The optical system 110 is provided in common to the two light emitting devices 1B and 1C, and is optically coupled to the light emitting surfaces of the light emitting devices 1B and 1C. In one example, the optical axis of the optical system 110 coincides with an axis line AX2 that passes through the midpoints of the light emitting devices 1B and 1C and extends along the Z direction (see FIG. 1). The optical system 110 is a lens having a light collecting effect, such as a convex lens.

[0112] The light emitting devices 1B and 1C are the light emitting device 1 of the first embodiment. The element for focusing the emitted light, which is included in the phase distribution φ(x, y) of the phase modulation layer 15 of the light emitting devices 1B and 1C, has the single-focus type configuration described in the first embodiment. The element of the light emitting device 1B focuses the emitted light Lout1 output from the light emitting device 1B at a focus point U1 located between the light emitting device 1B and the optical system 110. The element of the light emitting device 1C focuses the emitted light Lout2 output from the light emitting device 1C at a focus point U2 located between the light emitting device 1C and the optical system 110. The positions of the focus points U1 and U2 are the same as those of the example shown in FIG.

[0113] 35 and 36, the output light Lout1 that has passed through the condensing point U1, and the output light Lout2 that has passed through the condensing point U2 pass through the optical system 110. The optical system 110 forms an image of the output light Lout1 and Lout2 on an image forming plane 115, and causes the output light Lout1 and Lout2 to interfere with each other on the image forming plane 115. The interference light thus generated is irradiated onto the surface of the object to be measured SA as the measurement light 105 shown in FIG. 34. Although each figure shows a single lens as the optical system 110, the optical system 110 may be configured by combining multiple lenses.

[0114] 37 is a diagram showing an interference light image on imaging plane 115, i.e., an intensity change pattern of measurement light 105. As shown in the figure, the pattern of measurement light 105 is a stripe pattern W1 in which the light intensity changes periodically like a sine wave along a certain direction A.

[0115] Referring again to Fig. 34, the imaging unit 103 is configured by a device having sensitivity to the measurement light 105 emitted from the light source device 102. As the imaging unit 103, for example, a CCD (Charge Coupled Device) camera, a CMOS (Complementary MOS) camera, or other two-dimensional image sensors can be used. The imaging unit 103 images the measurement object SA in a state where it is irradiated with the measurement light 105, and outputs an output signal indicating the imaging result to the measurement unit 104.

[0116] The measurement unit 104 is configured by a computer system including, for example, a processor, a memory, and the like. The measurement unit 104 executes various control functions by the processor. Examples of the computer system include a personal computer, a microcomputer, a cloud server, and a smart device (such as a smartphone or a tablet terminal). The measurement unit 104 may be configured by a programmable logic controller (PLC) or an integrated circuit such as a field-programmable gate array (FPGA).

[0117] The measuring unit 104 is communicably connected to the imaging unit 103, and performs three-dimensional shape measurement of the measurement object SA based on a signal input from the imaging unit 103. In this embodiment, the measuring unit 104 measures the three-dimensional shape of the measurement object SA based on a phase shift method using a sinusoidal stripe pattern W1. That is, the measurement is performed using a plurality of sinusoidal stripe patterns W1 in which the period T of the sine wave is equally divided into N (N is an integer) and the phase is shifted by T / N. In other words, the phases of the plurality of sinusoidal stripe patterns W1 are shifted by 2π / N. Such a phase shift can be realized, for example, by gradually moving the positions of the focusing points U1 and U2 in a direction intersecting with the axis AX.

[0118] As an example, a case will be shown in which four sinusoidal stripe patterns W1, each having a phase shift of π / 2, are used. The light intensities of the measurement light 105 having the four sinusoidal stripe patterns W1 are I0 to I3, respectively, and the coordinates of the pixels of the imaging unit 103 are (x, y). The light intensities I0 to I3 on ​​the surface of the measurement object SA are expressed by the following formulas (32) to (35). Ia(x, y) is the amplitude of the lattice pattern, Ib(x, y) is the background intensity, and θ(x, y) is the initial phase.

number

number

number

number

[0119] The initial phase θ can be calculated by tan θ=-(I3-I1) / (I2-I0). When the phase shift number of the sinusoidal stripe pattern W1 is N, the initial phase θ can be calculated by the following formula (36).

number

[0120] When using such a phase shift method, the measured phase is converted into the height of the object SA to be measured, so that the height of the object SA can be measured at intervals smaller than the pitch of the sinusoidal stripe pattern W1.

[0121] According to the light source device 102A or 102B included in the three-dimensional measurement system 101 of this embodiment, as described above, interference fringes are generated by two outgoing lights Lout1 and Lout2 emitted toward the light collection points U1 and U2, respectively. The interference fringes are an optical image in which the light intensity increases and decreases sinusoidally along a certain direction, that is, a stripe pattern W1. Such a stripe pattern W1 can be suitably used in the three-dimensional measurement system 101. Furthermore, the light emitting devices 1A to 1C included in the light source device 102A or 102B can be significantly miniaturized compared to conventional light sources. Therefore, the light source device 102A or 102B can be arranged in an extremely small space, and can be inserted into a small space that was previously impossible, such as inside the body, such as the oral cavity or body cavity, inside a tube, a gap in a wall, or a gap between furniture, equipment, etc. and a floor. Therefore, image diagnosis and examination in these can be facilitated.

[0122] As in this embodiment, the light source devices 102A and 102B may include an optical system 110 optically coupled to the light emitting devices 1A to 1C. The light condensing points U1 and U2 may be located between the light emitting devices 1A to 1C and the optical system 110, and the emitted lights Lout1 and Lout2 may interfere with each other after passing through the optical system 110. In this case, the size Ja of the area irradiated with the stripe pattern W1 (see Figs. 35 and 36) is mainly determined by the focal length of the light emitting devices 1A to 1C and the optical axis position and focal length of the optical system 110. Therefore, it is possible to freely expand the irradiation surface of the stripe pattern W1 regardless of the area of ​​the light emitting surface of the light emitting devices 1A to 1C. In addition, by arbitrarily selecting the interval Jb between the light condensing points U1 and U2, it is possible to freely control the irradiation angle θp, which is the angle between the optical axis of the emitted lights Lout1 and Lout2 and the axis AX1 or AX2. Therefore, the stripe spacing (period of intensity change) of the stripe pattern W1 can be changed arbitrarily, and an appropriate stripe spacing according to the size of the object to be measured SA can be realized.

[0123] Fig. 38 is a schematic diagram showing the configuration of a light source device 102C according to a comparative example. Unlike the light source device 102B (see Fig. 36), the phase distribution φ(x, y) of the light emitting devices 1B and 1C of the light source device 102C does not include an element for focusing, and emits the emitted light LoutA and LoutB as plane waves, respectively. In addition, the light source device 102C does not include an optical system 110. The emitted light LoutA from the light emitting device 1B is emitted in a direction Aa inclined by an angle θa with respect to the axis line AX2. The emitted light LoutB from the light emitting device 1C is emitted in a direction Ab inclined by an angle -θa with respect to the axis line AX2. The emitted light LoutA and LoutB interfere with each other to form interference fringes, i.e., a stripe pattern W1 (see Fig. 37) on the imaging plane 115.

[0124] In this light source device 102C, the size Ja of the area where the stripe pattern W1 is irradiated is mainly determined by the size of the light emitting surface of each of the light emitting devices 1B and 1C. It is difficult to make the size Ja of the area where the stripe pattern W1 is irradiated larger than the light emitting surface of each of the light emitting devices 1B and 1C. Therefore, the size of the measurable object SA is limited.

[0125] In addition, in order to change the stripe interval (period of intensity change) of the stripe pattern W1, it is necessary to control the angle θa of the emission directions Aa, Ab of the emitted lights LoutA, LoutB. FIG. 39 shows a schematic diagram of the state when the angle θa is increased. As is clear from a comparison between FIG. 39 and FIG. 38, when the angle θa is increased, the irradiation surface (imaging surface 115) of the stripe pattern W1 approaches the light-emitting devices 1B, 1C. Therefore, in order to change the stripe interval of the stripe pattern W1, it is necessary to change the arrangement of the light-emitting devices 1B, 1C, which causes a problem that the degree of freedom of control of the stripe interval is low. In contrast, in the light source device 102B of this embodiment, in order to change the stripe interval of the stripe pattern W1, it is sufficient to change the interval between the light-concentration points U1, U2 and the focal length of the optical system 110, and there is no need to change the arrangement of the light-emitting devices 1B, 1C. Therefore, the stripe interval of the stripe pattern W1 can be easily changed.

[0126] As described above, the light source device 102 of this embodiment emits the emitted light Lout1, Lout2 while concentrating them by devising the phase distribution φ(x, y) of the S-iPM laser, and causes them to interfere with each other. The mutual interference between two lights can be realized not only by the S-iPM laser, but also by spatially modulating the phase of the light using, for example, a phase-modulating spatial light modulator (SLM). However, the technical concepts of the method using the SLM and the method of this embodiment using the iPM laser are significantly different.

[0127] The SLM outputs modulated light in a direction intersecting with the light modulation surface. In the S-iPM laser, signal light such as +1st order light and -1st order light corresponds to the modulated light of the SLM, but ingenuity is required to output only the signal light in a direction intersecting with the light emission surface. Conventionally, Γ-point oscillation S-iPM lasers have been researched, but Γ-point oscillation S-iPM lasers emit 0th order light in a direction perpendicular to the light emission surface. Since the 0th order light is not affected by the phase distribution φ(x, y), it becomes unnecessary light, i.e., noise, when light is focused and emitted as in this embodiment. In addition, when the S-iPM laser is oscillated at the M point, it is possible to suppress the emission of the 0th order light in a direction perpendicular to the light emission surface. However, when the S-iPM laser is simply oscillated at the M point, the signal light such as +1st order light and -1st order light is also not emitted in a direction intersecting with the light emission surface. To address this issue, in this embodiment, a diffraction vector V1 is added to the in-plane wave vectors K1 to K4, and the magnitude of at least one of the in-plane wave vectors K1 to K4 is made smaller than 2π / λ (light line), making it possible to emit signal light in a direction intersecting with the light emission surface. Such an idea is not easily conceived of in a method using an SLM.

[0128] In addition, while it has been demonstrated that S-iPM lasers can form two-dimensional holograms in a plane perpendicular to the light emission direction (Z direction), the light-emitting device 1 of this embodiment can also form three-dimensional holograms by varying the positions of multiple light-focusing points in the Z direction. Formation of three-dimensional holograms using S-iPM lasers has not been demonstrated so far.

[0129] Also, while it has been conventional to focus modulated light by imparting a lens effect to the phase pattern of an SLM, in an SLM the lens effect is achieved by simply modulating the phase of light for each pixel. In contrast, in an S-iPM laser, the phase of a plane wave in a resonant state is modulated while propagating inside the phase modulation layer 15, so it was unclear whether or not the focusing effect could be achieved. The inventors actually fabricated such an S-iPM laser and conducted experiments, which revealed that the focusing effect could be achieved.

[0130] (First Modification) FIG. 40 is a schematic diagram partially illustrating the configuration of a light source device 102D according to a first modified example. In addition to the configuration of the light source device 102A (see FIG. 35) of the second embodiment, the light source device 102D further includes a mask 112 for a mode filter. The mask 112 has two optical apertures 113 and 114 that pass the output lights Lout1 and Lout2, respectively. The position of one optical aperture 113 in a direction along the axis AX1 (i.e., the Z direction) overlaps with the condensing point U1. The position of the other optical aperture 114 in the same direction overlaps with the condensing point U2. The inner diameter of the optical aperture 113 is larger than the light diameter (beam waist diameter) of the output light Lout1 at the condensing point U1. The inner diameter of the optical aperture 114 is larger than the light diameter (beam waist diameter) of the output light Lout2 at the condensing point U2. The configuration of the light source device 102D other than the mask 112 is the same as that of the light source device 102A of the second embodiment. The light source device 102B of the second embodiment may further include a mask 112, similar to this modification.

[0131] Parts (a) and (b) of FIG. 41 are diagrams for explaining the effect of providing the mask 112. When the output lights Lout1 and Lout2 are emitted from the light-emitting devices 1A to 1C, the ghost light LG due to −1st order light and / or back surface reflection is diffused and emitted from the light-emitting devices 1A to 1C at the same time as the output lights Lout1 and Lout2. The ghost light LG is, for example, light (for example, −1st order light) having a different sign of the diffraction order from that of the output lights Lout1 and Lout2. When the mask 112 is not provided as shown in part (a) of FIG. 41, the ghost light LG overlaps with the output lights Lout1 and Lout2, causing a disturbance in the spatial mode of the output lights Lout1 and Lout2. In contrast, when the mask 112 is provided as shown in part (b) of FIG. 41, only the output lights Lout1 and Lout2 pass through the optical apertures 113 and 114, and the ghost light LG is blocked by the mask 112. Therefore, the ghost light LG can be removed from the output lights Lout1 and Lout2, and mode cleaning of the output lights Lout1 and Lout2 can be easily performed.

[0132] Third embodiment Next, a third embodiment will be described. In the above-described embodiments, the case where light is condensed into a point shape has been described. In this embodiment, the case where light is condensed only in one direction will be described.

[0133] FIG. 42 shows a lens phase distribution φ for focusing light in only one direction. L This is a diagram showing an example of (x, y). In this figure, the magnitude of the phase is expressed by the shade of color, with the darker the color, the closer it is to 0 (rad), and the lighter the color, the closer it is to 2π (rad). In this example, the phase becomes larger as it moves away from the position of Y=0 in the Y direction (the second direction in this embodiment), and the phase is constant in the X direction (the first direction in this embodiment). This lens phase distribution φ L (x, y) can act as a one-dimensional (Y direction) concave lens element for the emitted light. Lens phase distribution φ as a one-dimensional lens element L (x, y) are expressed by the formula (37). Here, λ is the wavelength in the medium in the phase modulation layer 15, (x, y) are the lattice point positions in the plane, and f is the focal length. When the sign on the right side is positive, it becomes a one-dimensional concave lens element, and the -1st order light is focused in the area where z>0. When the sign on the right side is negative, it becomes a one-dimensional convex lens element, and the 1st order light is focused in the area where z>0. The focal length f is, for example, 100 μm.

number

[0134] Fig. 43 is a conceptual diagram showing the operation of forming a striped light image. Fig. 43(a) shows the hologram phase distribution φ H 43(b) shows a schematic example of an optical image formed on a fictitious plane by only (x, y). This optical image includes multiple bright points E1 arranged in a line and at equal intervals on the X axis. FIG. 43(b) shows a hologram phase distribution φ that forms the optical image shown in FIG. 43(a). H (x,y) is the lens phase distribution φ shown in FIG. L The optical image obtained by superposing (x, y) is shown diagrammatically. Hologram phase distribution φ HThe multiple bright spots E1 formed by (x, y) are reflected by the lens phase distribution φ as shown in FIG. L (x, y) are stretched in the Y direction to form multiple bright lines L1. This is the result of each bright spot E1 being once focused in the Y direction and then expanding in the same direction. In this way, the hologram phase distribution φ that forms multiple bright spots E1 aligned in a line and at equal intervals on the X axis H For (x, y), the lens phase distribution φ as a one-dimensional lens element that focuses light in a direction perpendicular to the arrangement direction L By superimposing (x, y), a striped light image can be obtained. The striped light image can be suitably used in, for example, the three-dimensional measurement system of the second embodiment. The inventors have prototyped such a light-emitting device. FIG. 44 shows a far-field image of a striped light image emitted from the prototype light-emitting device. For comparison, FIG. 45 shows a lens phase distribution φ L Without using (x,y), the hologram phase distribution φ H This shows a far-field image when a striped light image is formed only by (x, y). Compared with Fig. 45, the far-field image shown in Fig. 44 shows that the noise (uneven brightness) contained in the light image is significantly reduced, and a clear striped pattern is obtained. Such a clear striped light image contributes to improving the measurement accuracy in a three-dimensional measurement system. Also, compared with the case where a separate lens component such as a cylindrical lens is provided, it is possible to focus light to an extremely short focal length, for example, 100 μm, and the striped pattern can be extended longer.

[0135] Fig. 46 is a conceptual diagram showing an operation for forming a striped light image different from that described above. The aspect shown in Fig. 46 differs from the aspect shown in Fig. 43 in that the hologram phase distribution φ H(x, y) is the shape of the light image formed by the X-axis. That is, the light image shown in FIG. 46(a) includes a plurality of bright spot groups EA1 arranged in a row and at equal intervals on the X-axis. Each bright spot group EA1 includes four bright spots E1, E2, E3, and E4. The light intensities of the bright spots E2 and E3 are smaller than that of the bright spot E1 and are equal to each other. The light intensity of the bright spot E4 is smaller than that of the bright spots E2 and E3. In the figure, the light intensity of each bright spot is represented by a shade of color. The darker the color, the higher the light intensity, and the lighter the color, the lower the light intensity. The bright spots E2 and E3 are arranged on both sides of the bright spot E1 in the X-axis. The bright spot E4 is arranged in the X-axis direction between the bright spot E2 (or E3) of the bright spot group EA1 to which the bright spot E4 belongs and the bright spot E3 (or E2) of the bright spot group EA1 adjacent to the bright spot group EA1. In the example shown in FIG. 46(a), the bright spots E1 to E4 are shifted from one another in the Y direction, but the Y direction positions of some or all of these may coincide with one another.

[0136] FIG. 46(b) shows the hologram phase distribution φ that forms the optical image shown in FIG. 46(a). H (x,y) is the lens phase distribution φ shown in FIG. L The optical image obtained by superposing (x, y) is shown diagrammatically. Hologram phase distribution φ H The multiple bright spot group EA1 formed by (x, y) is, as shown in FIG. 46(b), a lens phase distribution φ L The bright spots EA1 are stretched in the Y direction by (x, y) to form a group of multiple bright lines LA1. This is the result of each bright spot group EA1 being focused in the Y direction and then expanding in the same direction. Also, due to the difference in light intensity of each bright line included in the group of bright lines LA1, an approximately sinusoidal intensity distribution is obtained in the X direction. The striped light image obtained in this way can also be suitably used in the three-dimensional measurement system of the second embodiment.

[0137] Fig. 47 is a diagram showing an embodiment similar to that shown in Fig. 46. The embodiment shown in Fig. 47 differs from the embodiment shown in Fig. 46 in that the hologram phase distribution φ H(x, y) is the shape of the light image formed by the X-axis. That is, the light image shown in FIG. 47(a) includes a plurality of bright spot groups EA2 arranged in a row and at equal intervals on the X-axis. The plurality of bright spot groups EA2 are arranged apart from each other in the X-direction. Each bright spot group EA2 includes five bright spots E1, E2, E3, E4, and E5. The light intensities of the bright spots E2 and E3 are smaller than the light intensity of the bright spot E1 and are equal to each other. The light intensities of the bright spots E4 and E5 are smaller than the light intensity of the bright spots E2 and E3 and are equal to each other. The bright spots E2 and E3 are arranged on both sides of the bright spot E1 in the X-direction. The bright spots E4 and E5 are arranged on both sides of the bright spots E1 to E3 in the X-direction. In the example shown in FIG. 47(a), the Y-direction positions of the bright spots E1 to E5 are the same as each other, but some or all of them may be shifted from each other in the Y-direction. 47(a) shows an example of the relative values ​​of the light intensities of the bright spots E1 to E5 in a graph. In this example, when the light intensity of the bright spot E1 is 1.0, the light intensities of the bright spots E2 and E3 are 0.50, and the light intensities of the bright spots E4 and E5 are 0.25.

[0138] FIG. 47(b) shows the hologram phase distribution φ that forms the optical image shown in FIG. 47(a). H (x,y) is the lens phase distribution φ shown in FIG. L The optical image obtained by superposing (x, y) is shown diagrammatically. Hologram phase distribution φ H The multiple bright spot group EA2 formed by (x, y) is, as shown in FIG. 47(b), a lens phase distribution φ LThe light is stretched in the Y direction by (x, y) to form a group of multiple bright lines LA2. This is the result of each bright point group EA2 being once focused in the Y direction and then expanding in the same direction. In addition, due to the difference in light intensity of each bright line included in the group of bright lines LA2, an intensity distribution is obtained in which the light intensity increases and decreases in a substantially sinusoidal manner along the X direction. The striped light image thus obtained can also be suitably used in the three-dimensional measurement system of the second embodiment. The inventor has prototyped such a light-emitting device. Figure 48 is a far-field image of a striped light image emitted from the prototype light-emitting device. Compared with Figure 45, it can be seen that the noise (uneven brightness) included in the light image is significantly reduced and a clear striped pattern is obtained in the far-field image shown in Figure 48.

[0139] Fig. 49 is a diagram showing another embodiment similar to that shown in Fig. 46. The embodiment shown in Fig. 49 differs from that shown in Fig. 46 in that the hologram phase distribution φ H (x, y) is the shape of the light image formed by the X-axis. That is, the light image shown in FIG. 49(a) includes a plurality of bright spot groups EA3 arranged in a row and at equal intervals on the X-axis. The plurality of bright spot groups EA3 are arranged apart from each other in the X-direction. Each bright spot group EA3 includes five bright spots E6, E7, E8, E9, and E10. In the illustrated example, the light intensities of the bright spots E6 to E10 are equal to each other, but as in the embodiment shown in FIG. 47(a), for example, the light intensities of the bright spots E7 and E9 may be smaller than the light intensity of the bright spot E8, and the light intensities of the bright spots E6 and E10 may be smaller than the light intensity of the bright spots E7 and E9. The bright spots E6 to E10 are arranged in this order in the X-direction, and when the bright spots E6 to E10 are projected onto the X-axis, they are continuous without gaps. In the example shown in FIG. 49(a), the bright spots E6 to E10 are shifted from each other in the Y-axis, but the Y-direction positions of some or all of these may be the same.

[0140] FIG. 49(b) shows the hologram phase distribution φ that forms the optical image shown in FIG. 49(a). H (x,y) is the lens phase distribution φ shown in FIG. L The optical image obtained by superposing (x, y) is shown diagrammatically. Hologram phase distribution φ HThe multiple bright spot group EA3 formed by (x, y) is, as shown in FIG. 49(b), a lens phase distribution φ L The bright spots are stretched in the Y direction by (x, y) to form a group of multiple bright lines LA3. This is the result of each bright spot group EA3 being once focused in the Y direction and then expanding in the same direction. Furthermore, even in the stretched group of bright lines LA3, the bright lines L6 to L10 are adjacent to each other in the X direction. The inventor has prototyped such a light-emitting device. Figure 50 is a far-field image of a striped light image emitted from the prototype light-emitting device. Compared with Figure 45, it can be seen that the noise (uneven brightness) contained in the light image is significantly reduced and the stripe pattern is more clearly defined in the far-field image shown in Figure 50.

[0141] (Second Modification) Here, as a modified example of the third embodiment, it is considered to have a slight light-collecting effect not only in the Y direction but also in the X direction. That is, a lens phase distribution φ in which the focal length in the X direction is longer than the focal length in the Y direction is L Set (x, y). Figure 51 shows such a lens phase distribution φ L This is a diagram showing an example of (x, y). In this figure, the magnitude of the phase is expressed by the shade of color, and the darker the color, the closer it is to 0 (rad), and the lighter the color, the closer it is to 2π (rad). This lens phase distribution φ L (x, y) can act as an asymmetric concave lens element for the emitted light. The lens phase distribution φ as an asymmetric lens element L (x, y) is expressed by the formula (38), where λ is the wavelength in the medium of the phase modulation layer 15, (x, y) is the lattice point position in the plane, and f x is the focal length in the X direction, and f y is the focal length in the Y direction. If the sign on the right hand side is positive, the lens element becomes asymmetrical concave, and the 1st order light is focused in the area where z>0. If the sign on the right hand side is negative, the lens element becomes asymmetrical convex, and the -1st order light is focused in the area where z>0. The focal length in the X direction f x is, for example, 10 mm, and the focal length in the Y direction f y is, for example, 100 μm.

number

[0142] Fig. 52 is a conceptual diagram showing the operation of forming a striped optical image. Fig. 52(a) shows the hologram phase distribution φ H FIG. 52(b) is a diagram showing a schematic example of an optical image formed only by (x, y), and shows an optical image similar to that shown in FIG. 43(a). FIG. 52(b) shows a hologram phase distribution φ that forms the optical image shown in FIG. H (x,y) is the lens phase distribution φ shown in FIG. L 52(b), the light image obtained by superimposing (x, y) is shown. In this modification, the multiple emission lines L1 are also shown in the lens phase distribution φ L (x,y) in the Y direction. At the same time, the multiple emission lines L1 are stretched in the Y direction by the lens phase distribution φ L The light is also slightly elongated in the X direction by (x, y). In this case, a striped light image can also be obtained. Such a striped light image can also be suitably used in the three-dimensional measurement system of the second embodiment, for example.

[0143] The present inventors have prototyped a light-emitting device of this modification. Figure 53 shows a far-field pattern of a striped light image emitted from the prototype light-emitting device. For comparison, an asymmetric lens phase distribution φ L Instead of (x,y), we use the one-dimensional lens phase distribution φ shown in FIG. L The far-field pattern of the prototype light-emitting device when (x, y) is used is shown in Fig. 44. Comparing Fig. 53 with Fig. 44, the asymmetric lens phase distribution φ L According to (x, y), the width of the stripes can be adjusted widely, and can be used to adjust the width appropriately required for the three-dimensional measurement system.

[0144] The light emitting device and the light source apparatus according to the present disclosure are not limited to the above-mentioned embodiment, and various other modifications are possible. For example, the above-mentioned embodiment illustrates a laser element made of a GaAs-based, InP-based, and nitride-based (particularly GaN-based) compound semiconductor, but the present disclosure can be applied to laser elements made of various semiconductor materials other than these. In addition, the above-mentioned embodiment illustrates an example in which an active layer provided on a semiconductor substrate common to the phase modulation layer is used as a light emitting portion, but in the present disclosure, the light emitting portion may be provided separately from the semiconductor substrate. As long as the light emitting portion is optically coupled to the phase modulation layer and supplies light to the phase modulation layer, even with such a configuration, the same effects as those of the above-mentioned embodiment can be preferably achieved. [Explanation of symbols]

[0145] 1, 1A to 1C...light-emitting device, 10...semiconductor substrate, 10a...main surface, 10b...rear surface, 11...cladding layer, 12...active layer, 13...cladding layer, 14...contact layer, 15...phase modulation layer, 15a...basic layer, 15b...modified refractive index area, 16, 17...electrode, 17a...aperture, 18...protective film, 19...anti-reflection film, 50A, 50B...random pattern, 51...area, 52...selected area, 53...non-selected area, 100...S-iPM laser, 101...three-dimensional measurement system, 102, 102A to 102D...light source device, 103...imaging unit, 104...measurement unit, 105...measurement light, 106...stage, 110...optical system, 112...mask, 113, 114...optical aperture, 115...imaging surface, A...direction, Aa, Ab ...Emission direction, AX,AX1,AX2...axis line, B1...basic reciprocal lattice vector, D...straight line, E1~E10...bright spot, EA1~EA3...bright spot group, FR...image area, G...center of gravity, K1 ~K4,Ka,Kb...In-plane wave number vector, L1,L6~L10...Emission line, LA1~LA3...Emission line group, La...1st order light, Lb...-1st order light, LG...Ghost light, LL...Light line In, LL2...area, LM...light image, Lout,Lout1,Lout2,LoutA,LoutB...outgoing light, O...lattice point, PM...projection plane, R...unit component area, RIN...inner area, ROUT...outer area, SA...object to be measured, U, U1, U2, UD...focusing point, V1...diffraction vector, W1...stripe pattern, θa...angle, θp...irradiation angle.

Claims

1. A light emitting portion; a phase modulation layer optically coupled to the light emitting section, the phase modulation layer including a base layer and a plurality of modified refractive index areas having a refractive index different from that of the base layer and two-dimensionally distributed in a plane perpendicular to a thickness direction; Equipped with when a virtual lattice is set within the plane, the centers of gravity of the modified refractive index areas are arranged in a form having individual relationships with corresponding lattice points according to a predetermined phase distribution, A light emitting device, wherein the predetermined phase distribution includes elements for concentrating emitted light in at least one direction.

2. The light emitting device according to claim 1 , wherein the element of the predetermined phase distribution is an element for focusing the emitted light into at least two focusing points.

3. The light-emitting device of claim 2, wherein the predetermined phase distribution includes as its element a phase distribution obtained by combining a first phase distribution for emitting the emitted light toward at least two points and a second phase distribution for concentrating the emitted light.

4. The light-emitting device according to claim 2 , wherein the at least two light-collecting points are aligned in a direction intersecting the thickness direction.

5. the elements of the predetermined phase distribution are elements for focusing the emitted light to at least four focusing points, The light emitting device according to claim 2 or 3, wherein the at least four light focusing points are distributed three-dimensionally.

6. The light-emitting device of claim 1, wherein the predetermined phase distribution is a superposition of a hologram phase distribution that forms a plurality of bright spots arranged in a first direction and a lens phase distribution that has a focusing effect only in a second direction that intersects the first direction.

7. the predetermined phase distribution is obtained by superposing a hologram phase distribution that forms a group of multiple bright points arranged in a first direction and a lens phase distribution that has a light-collecting effect only in a second direction intersecting the first direction, The light emitting device of claim 1 , wherein each group of bright spots includes a plurality of bright spots, and at least two of the plurality of bright spots have different light intensities from each other.

8. Each of the bright point groups includes a first bright point, a second bright point, and a third bright point that are located at different positions in the first direction, the second bright spot and the third bright spot are disposed at positions sandwiching the first bright spot, The light emitting device of claim 7 , wherein the light intensity of the second and third bright spots is less than the light intensity of the first bright spot.

9. 2. The light-emitting device of claim 1, wherein the predetermined phase distribution is a superposition of a hologram phase distribution that forms a plurality of bright spots arranged in a first direction and a lens phase distribution that has a focusing effect in the first direction and a second direction intersecting the first direction, and whose focal length in the first direction is longer than its focal length in the second direction.

10. A light-emitting device as described in any one of claims 1 to 9, wherein the center of gravity of each modified refractive index area is arranged in either one of a first form in which the center of gravity of each modified refractive index area is positioned away from a corresponding lattice point and has an individual rotation angle around the lattice point according to a predetermined phase distribution, and a second form in which the center of gravity of each modified refractive index area is positioned on a straight line that passes through a lattice point of the virtual lattice and is inclined with respect to the lattice, and the distance between the center of gravity of each modified refractive index area and the lattice point corresponding to each modified refractive index area is individually set according to the predetermined phase distribution.

11. The lattice spacing of the virtual lattice and the emission wavelength λ of the light emitting portion satisfy the condition for M-point oscillation, The light-emitting device according to any one of claims 1 to 10, wherein four in-plane wave vectors each including a wave number spread corresponding to an angular spread of light emitted from the light-emitting device are formed in a reciprocal lattice space of the phase modulation layer, and the magnitude of at least one of the in-plane wave vectors is smaller than 2π / λ.

12. A light emitting device comprising first and second light emitting devices according to claim 1, the element of the predetermined phase distribution of the first light-emitting device focuses a first light emitted from the first light-emitting device toward a first focusing point; the element of the predetermined phase distribution of the second light emitting device focuses a second output light from the second light emitting device to a second focusing point aligned with the first focusing point; A light source device that generates interference fringes by causing the first emitted light and the second emitted light to interfere with each other.

13. an optical system optically coupled to the first and second light emitting devices; the first light focusing point is located between the first light emitting device and the optical system; the second light-focusing point is located between the second light-emitting device and the optical system; The light source device according to claim 12 , wherein the first emitted light and the second emitted light interfere with each other after passing through the optical system.

14. A light-emitting device according to any one of claims 2 to 4, the elements of the predetermined phase distribution of the light emitting device focus a first output light from the light emitting device to a first focus point and focus a second output light from the light emitting device to a second focus point; A light source device that generates interference fringes by causing the first emitted light and the second emitted light to interfere with each other.

15. an optical system optically coupled to the light emitting device; the first and second light focusing points are located between the light emitting device and the optical system; The light source device according to claim 14 , wherein the first emitted light and the second emitted light interfere with each other after passing through the optical system.

Images