Light-emitting device

Abstract

This light-emitting device comprises an active layer as a light-emitting unit, and a phase modulation layer 15. The phase modulation layer 15 is optically coupled to the active layer, and includes a basic layer, and a plurality of different refractive index regions having a refractive index different from that of the basic layer and two-dimensionally distributed in a plane perpendicular to the thickness direction. The center of gravity of each different refractive index region is disposed at a relative position corresponding to the phase modulation amount of a predetermined phase distribution with respect to the corresponding lattice point of a virtual lattice. The predetermined phase distribution has, around the optical axis 21, a region 153 including a two-dimensional lens pattern in which phases change in two directions orthogonal to each other. By the two-dimensional lens pattern, the diameter of a beam 245 emitted from the region 153 is once reduced at a first position 33 and then expanded in an annular shape.

Description

Light-emitting devices

[0001] This application claims priority to Japanese Patent Application No. 2023-126151, filed on August 2, 2023, and incorporates by reference all of the contents of said Japanese application.

[0002] Patent Document 1 discloses a light-emitting device. The light-emitting device includes a light-emitting section and a phase modulation layer. The phase modulation layer is optically coupled to the light-emitting section. The phase modulation layer includes a base layer and multiple modified refractive index areas. The multiple modified refractive index areas have refractive indices different from those of the base 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 center of gravity of each modified refractive index area is located away from the corresponding lattice point and has an individual rotation angle around the lattice point according to a predetermined phase distribution. The lattice spacing of the virtual square lattice and the emission wavelength of the light-emitting section satisfy the condition for M-point oscillation. The predetermined phase distribution includes an element for focusing the emitted light in at least one direction.

[0003] Patent Document 2 discloses a semiconductor light-emitting device. The semiconductor light-emitting device outputs an optical image in a direction inclined with respect to a direction perpendicular to a major surface of a semiconductor substrate. The semiconductor light-emitting device includes an active layer, a cladding layer, a contact layer, a phase modulation layer, and an electrode. The active layer is provided on the major surface of the semiconductor substrate. The cladding layer is provided on the active layer. The contact layer is provided on the cladding layer. The phase modulation layer is provided between the semiconductor substrate and the active layer or between the active layer and the cladding layer. The electrode is provided on the contact layer. The phase modulation layer includes a first region overlapping with the electrode when viewed in the thickness direction of the phase modulation layer, and a second region excluding the first region. The phase modulation layer has a base layer and multiple modified refractive index regions having a refractive index different from that of the base layer. When a virtual square lattice is defined in a plane perpendicular to the thickness direction of the phase modulation layer, the centers of gravity of the multiple modified refractive index regions included in the second region are positioned away from lattice points of the virtual square lattice and have a rotation angle around the lattice point according to the optical image. The optical image is completed only by the second region of the phase modulation layer.

[0004] Non-Patent Document 1 discloses a method for forming Bessel beams using an axicon lens or a metalens.

[0005] JP 2022-154929 A JP 2018-206921 A

[0006] Wei Ting Chen et al., "Generation of wavelength-independent subwavelength Bessel beams using metasurfaces", Light: Science & Applications 6, e16259 (2017)Y. Kurosaka et al., "Effects of non-lasing band in two-dimensional photonic-crystal lasers clarified using omnidirectional band structure," Opt. Express 20, 21773-21783 (2012)

[0007] Conventionally, in devices equipped with a light source, optical components such as lenses are used as an optical system for concentrating light from the light source. When miniaturization of such light source devices is required, significant miniaturization is possible by using, for example, a semiconductor light-emitting element as the light source. However, miniaturization of optical components for concentrating light is difficult, which is a factor hindering miniaturization of light source devices. Therefore, the light-emitting device described in Patent Document 1 includes a light-emitting portion and a phase modulation layer, and the phase distribution of the phase modulation layer is designed so as to concentrate the emitted light in at least one direction.

[0008] In this case, depending on the application, the distance between the object to be irradiated with light and the light source device may vary. For example, when a light source device is used in an endoscope used in medical care, the position of the endoscope relative to the object to be imaged, which is the object to be irradiated, is not predetermined. Therefore, it is necessary to allow a certain degree of variation in the distance between the object to be imaged and the light source device. Therefore, it is desirable for the focused spot to extend over a wide range along the light emission direction (in other words, to have a deep focal depth).

[0009] Therefore, an object of the present disclosure is to provide a light-emitting device in which the focused spot can extend over a wide range along the light emission direction.

[0010] [1] A first 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. The phase modulation layer includes a base layer and a plurality of modified refractive index areas. The plurality of modified refractive index areas have refractive indices different from those of the base layer and are distributed two-dimensionally in a plane perpendicular to the thickness direction. The centers of gravity of the plurality of modified refractive index areas are positioned relative to corresponding lattice points of a virtual lattice set in the plane at positions corresponding to the phase modulation amount of a predetermined phase distribution. The predetermined phase distribution has regions on both sides of the optical axis in the one direction, each including a one-dimensional lens pattern whose phase changes in the one direction. Due to the one-dimensional lens pattern, a first beam emitted from a region on one side of the region on the optical axis intersects with a second beam emitted from a region on the other side of the region on the optical axis at a first position and then separates.

[0011] In this first light-emitting device, the center of gravity of each modified refractive index area is positioned relative to a corresponding lattice point of a virtual lattice set in the plane, at a position corresponding to the phase modulation amount of a predetermined phase distribution. This structure allows for the generation of an optical image of any shape as a so-called S-iPM (Static-Integable Phase Modulating) laser. Additionally, in this first light-emitting device, beams phase-modulated by a one-dimensional lens pattern are emitted from areas arranged on both sides of the optical axis in one direction. The first beam emitted from the area on one side of the optical axis and the second beam emitted from the area on the other side of the optical axis intersect and then separate. When the first beam and the second beam intersect, the focused spot formed by the first beam and the second beam extends over a wide range along the light emission direction. That is, with the first light-emitting device described above, the focused spot extends over a wide range along the light emission direction, in other words, the depth of focus can be increased. This allows light to be focused on the target, regardless of fluctuations in the distance between the target and the first light-emitting device. In addition to +1st-order light, like an optical lens, an S-iPM laser also emits an in-plane standing wave in the opposite direction when resonating in the in-plane direction. This results in the emission of a beam symmetrical to the optical axis, known as -1st-order light. At this time, a third beam is emitted in a direction symmetrical to the first beam, and a fourth beam is emitted in a direction symmetrical to the second beam. The focused spot formed by the intersection of the first and third beams, and the focused spot formed by the intersection of the second and fourth beams, also extend along the light emission direction. By interfering with each other at these focused spots, the two beams can form a clear, striped optical image with minimal brightness unevenness. Therefore, the S-iPM laser can expand the range of stripe formation compared to a one-dimensional axicon lens.

[0012] [2] In the light-emitting device of [1] above, the one-dimensional lens pattern may be expressed by the following mathematical formula (1): Formula (1) includes a coordinate x in the one direction with the optical axis as the origin, a distance L from the optical axis to the edge of the one-dimensional lens pattern, a positive real number α, and a positive real number β. In this case, a one-dimensional lens pattern can be preferably realized in which the first beam and the second beam intersect with each other and then separate.

[0013] [3] In the first light-emitting device of [2] above, the positive real number α may be 1.0, and the positive real number β may be 2.0 or more and 20 or less. Alternatively, [4] in the first light-emitting device of [2] above, the positive real number α may be 0.8 or more and 1.2 or less, and the positive real number β may be 2.0 or more and 10 or less. Alternatively, [5] in the first light-emitting device of [2] above, the positive real number α may be 0.5 or less, and the positive real number β may be 5.0 or more and 20 or less. According to the inventor's simulation, in any of these cases, the first beam and the second beam can be made to interfere with each other at the focused spot to form a clear striped optical image with little brightness unevenness. The striped optical image is used, for example, for three-dimensional shape measurement. Therefore, with any of these first light-emitting devices, even if the distance between the irradiation target and the first light-emitting device fluctuates, three-dimensional shape measurement can be performed with high accuracy regardless of the fluctuation.

[0014] [6] In the first light-emitting device according to any one of [1] to [5] above, the predetermined phase distribution may have a gap including the optical axis between a region on one side of the optical axis and a region on the other side of the optical axis. In this case, the first position where the first beam and the second beam intersect can be controlled by the size of the gap. Therefore, the position of the focused spot in the light emission direction can be set arbitrarily.

[0015] [7] In the first light-emitting device of any one of [1] to [6] above, in the region, another one-dimensional lens pattern whose phase changes in one direction may be superimposed on the one-dimensional lens pattern, and the other one-dimensional lens pattern may emit a third beam separate from the first beam from a region on one side of the optical axis and a fourth beam separate from the second beam from a region on the other side of the optical axis, and the third beam and the fourth beam may intersect with each other at a second position different from the first position and then separate. In this case, multiple focused spots can be formed simultaneously using a single light-emitting device, thereby making it possible to reduce the size of the light source device compared to when a light-emitting device is provided for each focused spot.

[0016] [8] In the light-emitting device of [7] above, the first position and the second position may be on a common imaginary plane perpendicular to the optical axis. Alternatively, [9] in the light-emitting device of [7] above, the first position may be on a first imaginary plane perpendicular to the optical axis, and the second position may be on a second imaginary plane perpendicular to the optical axis and different from the first imaginary plane. In these cases, the range of the spread of the emission direction can be expanded.

[0017]

[10] A second 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. The phase modulation layer includes a base layer and a plurality of modified refractive index areas. The plurality of modified refractive index areas have refractive indices different from that of the base layer and are distributed two-dimensionally in a plane perpendicular to the thickness direction. The centers of gravity of the plurality of modified refractive index areas are positioned relative to corresponding lattice points of a virtual lattice set in the plane at positions corresponding to the phase modulation amount of a predetermined phase distribution. The predetermined phase distribution has a region around the optical axis that includes a two-dimensional lens pattern in which the phase changes in two mutually orthogonal directions. The two-dimensional lens pattern causes a first beam emitted from the region to first contract in diameter at a first position and then expand in diameter into an annular shape.

[0018] In this second light-emitting device, a beam phase-modulated by a two-dimensional lens pattern is emitted from a region arranged around the optical axis. The first beam emitted from the region first contracts in diameter and then expands in diameter into an annular shape. When the first beam contracts in diameter, the focused spot formed by the first beam extends over a wide range along the light-emitting direction. That is, with the second light-emitting device, the focused spot extends over a wide range along the light-emitting direction, in other words, the focal depth can be increased. This allows light to be focused on the target regardless of fluctuations in the distance between the target and the second light-emitting device.

[0019]

[11] In the second light-emitting device of

[10] above, the two-dimensional lens pattern may be expressed by the following formula (2): Formula (2) includes a distance r from the optical axis, a distance L from the optical axis to an edge of the two-dimensional lens pattern, a positive real number α, and a positive real number β. In this case, a two-dimensional lens pattern can be suitably realized in which the first beam first contracts in diameter and then expands in diameter into an annular shape. When the real number α in the above formula (2) is 1.0, the two-dimensional lens pattern functions as a so-called axicon lens, and the light emitted from the second light-emitting device becomes a Bessel beam. When the real number α is 2.0, the two-dimensional lens pattern becomes a general focusing lens (see, for example, Patent Document 1).

[0020]

[12] In the second light-emitting device of

[11] above, the positive real number α may be 1.2 or less. Alternatively,

[13] In the second light-emitting device of

[11] above, the positive real number α may be 0.5 or more and 1.2 or less, and the positive real number β may be 2.0 or more and 20 or less. Alternatively,

[14] In the second light-emitting device of

[11] above, the positive real number α may be 0.1 or more and 0.25 or less, and the positive real number β may be 5.0 or more and 50 or less. According to the inventor's simulation, in any of these cases, interference can be generated at the focused spot within the first beam, forming a clear concentric striped optical image with little brightness unevenness. The striped optical image can be used, for example, for three-dimensional shape measurement. Therefore, with any of these second light-emitting devices, even when the distance between the irradiation target and the second light-emitting device fluctuates, three-dimensional shape measurement can be performed with high accuracy regardless of the fluctuation.

[0021]

[15] In the second light-emitting device according to any one of

[10] to

[14] above, the shape of the region may have an opening including the optical axis. In this case, the first position where the diameter of the first beam is reduced can be controlled by the size of the opening. Therefore, the position of the focused spot in the light emission direction can be set arbitrarily.

[0022]

[16] In the second light-emitting device of any one of

[10] to

[15] above, in the region, another two-dimensional lens pattern whose phase changes in two directions may be superimposed on the two-dimensional lens pattern. A second beam separate from the first beam may be emitted from the region by the other two-dimensional lens pattern. The second beam may be first reduced in diameter at a second position different from the first position, and then expanded in diameter in an annular shape. In this case, multiple focused spots can be formed simultaneously using a single light-emitting device. Therefore, the light source device can be made smaller than when a light-emitting device is provided for each focused spot.

[0023]

[17] In the second light-emitting device of

[16] above, the first position and the second position may be on a common imaginary plane perpendicular to the optical axis. Alternatively,

[18] in the second light-emitting device of

[16] above, the first position may be on a first imaginary plane perpendicular to the optical axis, and the second position may be on a second imaginary plane perpendicular to the optical axis and different from the first imaginary plane. In these cases, the range of the spread of the emission direction can be expanded.

[0024]

[19] In the first light-emitting device of any one of [1] to [9] above or the second light-emitting device of any one of

[10] to

[18] above, the virtual lattice may be a virtual square lattice, and the lattice spacing of the virtual square lattice and the emission wavelength λ of the light-emitting portion may satisfy the condition for M-point oscillation. Four in-plane wave vectors, each including a wavenumber spread corresponding to the angular spread of light emitted from the light-emitting device, may be formed in the reciprocal lattice space of the phase modulation layer. The magnitude of at least one in-plane wave vector may be smaller than 2π / λ. In this light-emitting device, the lattice spacing of the virtual square lattice and the emission wavelength of the light-emitting portion satisfy the condition for M-point oscillation. Typically, in a standing wave state of M-point oscillation, light propagating within the phase modulation layer is totally reflected. This suppresses the output of both signal light and zero-order light, which are, for example, at least one of +1st-order light and -1st-order light. However, in this light-emitting device, in the reciprocal lattice space of the phase modulation layer, the standing wave undergoes phase modulation due to the phase distribution, forming four-directional in-plane wave vectors, each of which has 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, this adjustment of the in-plane wave vector is possible by devising the arrangement of each modified refractive index area. Furthermore, 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 portion of the signal light is output from the phase modulation layer. However, when the condition for M-point oscillation is satisfied, the zero-order light is not diffracted in the direction perpendicular to the plane and is not output from the phase modulation layer into the light line. In other words, this light-emitting device can remove the zero-order light contained in the output of the S-iPM laser from the light line, thereby outputting only the signal light. Therefore, the output of the zero-order light that does not contribute to focusing is suppressed, and only the signal light that can contribute to focusing can be output.

[0025] According to the present disclosure, it is possible to provide a light-emitting device in which the focused spot can extend over a wide range along the light emission direction.

[0026] FIG. 1 is a partially cutaway perspective view showing the configuration of a light-emitting device according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram showing a layered structure of a light-emitting device. FIG. 3 is a plan view showing a phase modulation layer. FIG. 4 is an enlarged view of a unit constituent region. FIG. 5 is a plan view showing an example of a phase distribution of a phase modulation layer. FIG. 6 is a diagram showing how two beams are emitted from each of the two regions shown in FIG. 5. FIG. 7 is a plan view showing another example of a phase distribution of a phase modulation layer. FIG. 8 is a diagram showing how two beams are emitted from each of the two regions shown in FIG. 7. FIG. 9 is a graph showing Equation (3). FIG. 10 is a graph showing the phase distribution φ ｎｏｒｍ 10 shows the case where the real number α is 2.0. FIG. 11 shows the phase distribution φ ｎｏｒｍ 11 shows the case where the real number α is 1.0. FIG. 12 shows the phase distribution φ ｎｏｒｍ 12 shows the case where the real number α is 0.5. FIG. 13 shows the phase distribution φ ｎｏｒｍ 13A and 13B are diagrams showing the simulation results of the shape of the focused spot obtained by (x). In Fig. 13, (a) shows the cross section of the focused spot along the XY plane, (b) shows the cross section of the focused spot along the XZ plane, and (c) shows the cross section of the focused spot along the YZ plane. Fig. 13 shows the case where the real number α is 2.0. Fig. 14 shows the phase distribution φ ｎｏｒｍ 14A and 14B are diagrams showing the simulation results of the shape of the focused spot obtained by (x). In Fig. 14, (a) shows the cross section of the focused spot along the XY plane, (b) shows the cross section of the focused spot along the XZ plane, and (c) shows the cross section of the focused spot along the YZ plane. Fig. 14 shows the case where the real number α is 1.0. Fig. 15 shows the phase distribution φ ｎｏｒｍ15A and 15B are diagrams showing simulation results of the shape of the focused spot obtained by (x). In FIG. 15, (a) shows a cross section of the focused spot along the XY plane, (b) shows a cross section of the focused spot along the XZ plane, and (c) shows a cross section of the focused spot along the YZ plane. FIG. 15 shows the case where the real number α is 0.5. FIG. 16 is a diagram showing how multiple beams are emitted from the phase modulation layer according to yet another example of the phase distribution of the phase modulation layer. FIG. 17 is a diagram showing first and second positions corresponding to two focused spots. FIG. 17A shows how the first and second positions are aligned on a common imaginary plane perpendicular to the optical axis. FIG. 17B shows how the first and second positions are distributed three-dimensionally (stereoscopically). FIG. 18 is a plan view showing yet another example of the phase distribution of the phase modulation layer. FIG. 19 is a diagram showing how beams are emitted from the region shown in FIG. 18. FIG. 20 is a plan view showing another example of the phase distribution of the phase modulation layer. Fig. 21 is a diagram showing how a beam is emitted from the region shown in Fig. 20. Fig. 22 shows the phase distribution φ ｎｏｒｍ 22 shows the case where the real number α is 2.0. FIG. 23 shows the phase distribution φ ｎｏｒｍ 23 shows the case where the real number α is 1.0. FIG. 24 shows the phase distribution φ ｎｏｒｍ 24 shows the case where the real number α is 0.5. FIG. 25 shows the phase distribution φ ｎｏｒｍ 25A and 25B are diagrams showing the simulation results of the shape of the focused spot obtained by (r). In Fig. 25, (a) shows the cross section of the focused spot along the XY plane, (b) shows the cross section of the focused spot along the XZ plane, and (c) shows the cross section of the focused spot along the YZ plane. Fig. 25 shows the case where the real number α is 2.0. Fig. 26 shows the phase distribution φ ｎｏｒｍ 26A and 26B are diagrams showing the simulation results of the shape of the focused spot obtained by (r). In Fig. 26, (a) shows the cross section of the focused spot along the XY plane, (b) shows the cross section of the focused spot along the XZ plane, and (c) shows the cross section of the focused spot along the YZ plane. Fig. 26 shows the case where the real number α is 1.0. Fig. 27 shows the phase distribution φ ｎｏｒｍ27A and 27B are diagrams showing simulation results of the shape of the focused spot obtained by (r). In FIG. 27, (a) shows a cross section of the focused spot along the XY plane, (b) shows a cross section of the focused spot along the XZ plane, and (c) shows a cross section of the focused spot along the YZ plane. FIG. 27 shows the case where the real number α is 0.5. FIG. 28 is a diagram showing how two beams are emitted from a phase modulation layer according to yet another example of the phase distribution of the phase modulation layer. FIG. 29 is a schematic diagram for comparing the light-focusing patterns. Part (a) of FIG. 29 shows how light is focused by a conventional lens pattern. Part (b) of FIG. 29 shows how light is focused by a lens pattern according to an embodiment of the present disclosure. FIG. 30 shows the far-field pattern (FFP) of a light-emitting device having a predetermined phase distribution including a two-dimensional lens pattern actually fabricated, and multiple beams are emitted from the light-emitting device. FIG. 31 is a diagram showing the near-field pattern (NFP) of a beam emitted from the light-emitting device. FIG. 31(a) shows a near-field pattern on the surface of the light-emitting device before oscillation. FIG. 31(b) and FIG. 31(c) show near-field patterns at positions z=50 μm and z=300 μm, respectively, with the surface of the light-emitting device as the reference (z=0). FIG. 32 shows a near-field pattern (NFP) of a beam emitted from the light-emitting device. FIG. 32(a), (b), and (c) show near-field patterns at positions z=550 μm, z=800 μm, and z=950 μm, respectively, with the surface of the light-emitting device as the reference (z=0). FIG. 33 shows a near-field pattern (NFP) of a beam emitted from the light-emitting device. FIG. 33(a) and (b) show near-field patterns at positions z=1050 μm and z=1250 μm, respectively, with the surface of the light-emitting device as the reference (z=0). Fig. 34 is a diagram in which two beams of -1st order light have been added to Fig. 8. Fig. 35 is a diagram in which a beam of -1st order light has been added to Fig. 21. Fig. 36 is a diagram that visualizes the difference in one-dimensional lens pattern depending on the real number β when the real number α = 1 in equation (3). Fig. 37 is a diagram showing striped light images that occur when the real number β in equation (3) that represents the one-dimensional lens pattern is set to various values. Fig. 37 shows a light image at z = 500 μm when the real number α = 1.0.Fig. 38 is a diagram showing striped light images that occur when the real number β in equation (3) representing a one-dimensional lens pattern is set to various values. Fig. 38 shows a light image at z = 1000 μm when the real number α = 1.0. Fig. 39 is a diagram showing striped light images that occur when the real number β in equation (3) representing a one-dimensional lens pattern is set to various values. Fig. 39 shows a light image at z = 1500 μm when the real number α = 1.0. Fig. 40 is a diagram showing striped light images that occur when the real number β in equation (3) representing a one-dimensional lens pattern is set to various values. Fig. 40 shows a light image at z = 2000 μm when the real number α = 1.0. Fig. 41 is a diagram showing striped light images that occur when the real number β in equation (3) representing a one-dimensional lens pattern is set to various values. Fig. 41 shows a light image at z = 2500 μm when the real number α = 1.0. Fig. 42 is a diagram showing striped light images that occur when the real number β in equation (3) representing a one-dimensional lens pattern is set to various values. Fig. 42 shows a light image at z = 3000 μm when the real number α = 1.0. Fig. 43 is a diagram showing striped light images that occur when the real number β in equation (3) representing a one-dimensional lens pattern is set to various values. Fig. 43 shows a light image when the real number α is set to 1.2. Fig. 44 is a diagram showing striped light images that occur when the real number β in equation (3) representing a one-dimensional lens pattern is set to various values. Fig. 44 shows a light image when the real number α is set to 0.8. Fig. 45 is a diagram showing striped light images that occur when the real number β in equation (3) representing a one-dimensional lens pattern is set to various values. Fig. 45 shows light images when the real number α is 0.5 and the real number β is 1.0, 2.0, and 5.0. Fig. 46 is a diagram showing striped light images that occur when the real number β in equation (3) that represents a one-dimensional lens pattern is set to various values. Fig. 46 shows light images when the real number α is set to 0.5 and the real number β is set to 10, 15, and 20. Fig. 47 is a diagram showing striped light images that occur when the real number β in equation (3) that represents a one-dimensional lens pattern is set to various values. Fig. 47 shows light images when the real number α is set to 0.25 and the real number β is set to 1.0, 2.0, and 5.0.Fig. 48 is a diagram showing a striped light image that occurs when the real number β in equation (3) representing a one-dimensional lens pattern is set to various values. Fig. 48 shows light images when the real number α is set to 0.25 and the real number β is set to 10, 15, and 20. Fig. 49 is a diagram showing a concentric striped light image that occurs in the region of Fig. 21 when the real number β in equation (4) representing a two-dimensional lens pattern is set to various values. Fig. 49 shows a light image when the real number α is set to 2.0. Fig. 50 is a diagram showing a concentric striped light image that occurs in the region of Fig. 21 when the real number β in equation (4) representing a two-dimensional lens pattern is set to various values. Fig. 50 shows a light image when the real number α is set to 1.5. Fig. 51 is a diagram showing a concentric striped light image that occurs in the region of Fig. 21 when the real number β in equation (4) representing a two-dimensional lens pattern is set to various values. Fig. 51 shows an optical image when the real number α is set to 1.2. Fig. 52 shows a concentric striped optical image that occurs in the region of Fig. 21 when the real number β in equation (4) representing the two-dimensional lens pattern is set to various values. Fig. 52 shows an optical image when the real number α is set to 1.0. Fig. 53 shows a concentric striped optical image that occurs in the region of Fig. 21 when the real number β in equation (4) representing the two-dimensional lens pattern is set to various values. Fig. 53 shows an optical image when the real number α is set to 0.8. Fig. 54 shows a concentric striped optical image that occurs in the region of Fig. 21 when the real number β in equation (4) representing the two-dimensional lens pattern is set to various values. Fig. 54 shows an optical image when the real number α is set to 0.5. Fig. 55 shows a concentric striped optical image that occurs in the region of Fig. 21 when the real number β in equation (4) representing the two-dimensional lens pattern is set to various values. Fig. 55 shows an optical image when the real number α is set to 0.25. Fig. 56 is a diagram showing a concentric striped optical image that occurs in the region of Fig. 21 when the real number β in equation (4) that indicates a two-dimensional lens pattern is set to various values. Fig. 56 shows an optical image when the real number α is set to 0.1. Fig. 57 is a plan view showing an example in which a substantially periodic refractive index structure is applied to a specific region of a phase modulation layer. Fig. 58 shows a phase image in spherical coordinates (r, θ). ｒｏｔ ,θ ｔｉｌｔ) is a diagram showing a phase distribution φ for adding a diffraction vector to an in-plane wave vector. Fig. 59 is a plan view showing a reciprocal lattice space related to a phase modulation layer of a light-emitting device that performs M-point oscillation. Fig. 60 is a conceptual diagram for explaining a state in which a diffraction vector is added to an in-plane wave vector. Fig. 61 is a diagram for schematically explaining a peripheral structure of a light line. Fig. 62 is a diagram for explaining a phase distribution φ for adding a diffraction vector. ２ FIG. 63 is a diagram conceptually showing an example of (x, y). FIG. 64 is a conceptual diagram for explaining a state in which a diffraction vector is added to the in-plane wave vector in four directions, from which the wave number spread is removed. FIG. 65 is a diagram showing the arrangement of modified refractive index areas in the phase modulation layer shown in FIG. 64. FIG. 66 is a diagram conceptually showing an example of a lens pattern φ Ｌ 67 is a conceptual diagram of an iterative algorithm used in the design of (x, y). Ｌ FIG. 68 is a diagram conceptually showing processing after designing a predetermined phase distribution φ(x, y). FIG. 69 is a diagram conceptually showing a design method for forming a plurality of focused spots. FIG. 70 is a conceptual diagram of a method for synthesizing a plurality of phase distributions. FIG. 71 is a diagram showing an example of a random pattern. FIG. 72 is a schematic diagram showing the configuration of a three-dimensional measurement system.

[0027] Specific examples of the light-emitting device 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 defined 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 duplicated explanations will be omitted. (First embodiment)

[0028] Fig. 1 is a partially cutaway perspective view showing the configuration of a light-emitting device 1 according to an embodiment of the present disclosure. Fig. 2 is a schematic diagram showing the layered structure of the light-emitting device 1. In Figs. 1 and 2, an XYZ Cartesian coordinate system is defined in which the Z axis is an axis extending in the thickness direction of the light-emitting device 1 at the center of the light-emitting device 1.

[0029] The light-emitting device 1 is a laser light source that forms standing waves in the XY plane and outputs phase-controlled plane waves in a direction intersecting its thickness direction. The light-emitting device 1 is a Si-iPM laser. The light-emitting device 1 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 relative to the Z direction, or a direction including both. The light-emitting device 1 may be a Si-iPMSEL (registered trademark) manufactured by Hamamatsu Photonics KK

[0030] 1 and 2 , the light-emitting device 1 includes an active layer 12 serving as a light-emitting portion provided on a primary surface 10a of a semiconductor substrate 10, a pair of cladding layers 11 and 13 sandwiching the active layer 12, and a contact layer 14 provided on the cladding layer 13. The semiconductor substrate 10, the cladding 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 bandgaps of the cladding layers 11 and 13 are larger than the energy bandgaps of the active layer 12. The thickness directions of the semiconductor substrate 10, the cladding layer 11, the active layer 12, the cladding layer 13, and the contact layer 14 coincide with the Z-axis direction.

[0031] 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.

[0032] 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. The plurality of modified refractive index areas 15b are made of a second refractive index medium having a refractive index different from that of the first refractive index medium and are present in the base layer 15a. The plurality of modified refractive index areas 15b include a lattice-like, approximately periodic structure. The equivalent refractive index of the mode is n, and the lattice spacing is a. In this case, the wavelength λ selected by the phase modulation layer 15 is ０ is λ ０ This wavelength λ is expressed as ０ is included in the emission wavelength range of the active layer 12. The phase modulation layer 15 emits light with a wavelength λ ０ The light incident on the phase modulation layer 15 forms a predetermined mode in accordance with the arrangement of the modified refractive index regions 15 b within the phase modulation layer 15, and is then emitted as laser light from the surface of the light-emitting device 1 to the outside.

[0033] The light-emitting device 1 further includes an electrode 16 and an electrode 17. The electrode 16 is provided on the contact layer 14. The electrode 17 is provided on the back surface 10b of the semiconductor substrate 10. The electrode 16 forms ohmic contact with the contact layer 14. The electrode 17 forms 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. Portions of the contact layer 14 other than the electrode 16 are covered with a protective film 18 (see FIG. 2 ). Portions of the contact layer 14 not in contact with the electrode 16 may be removed to limit the current range. Regions of the back surface 10b of the semiconductor substrate 10 other than the region where the electrode 17 is provided, including the inside of the opening 17a, are covered with an anti-reflection film 19. The anti-reflection film 19 in regions other than the opening 17a may be removed.

[0034] 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, as well as the light generated in the active layer 12, are efficiently confined between the cladding layers 11 and 13.

[0035] 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 passes through the opening 17a from the rear surface 10b and is directly output 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 passes through the opening 17a from the rear surface 10b and is output to the outside of the light-emitting device 1. At this time, signal light contained in the laser light is output in any direction, including a direction perpendicular to the main surface 10a and directions inclined relative to that direction.

[0036] It is this signal light that constitutes the light emitted from the light-emitting device 1. The signal light is mainly the first-order diffracted light or the -1st-order diffracted light of the laser light, or both. Hereinafter, the first-order diffracted light and the -1st-order diffracted light will be referred to as the first-order light and the -1st-order light, respectively. As will be described later, the output of the zeroth-order light of the laser light is suppressed from the phase modulation layer 15 of this embodiment.

[0037] FIG. 3 is a plan view showing 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 multiple 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 lattice is set in the XY plane for the phase modulation layer 15. In this embodiment, a square lattice is used as the virtual lattice, but the virtual lattice may be another lattice, such as a triangular lattice. In this embodiment, one side of the square lattice is parallel to the X axis, and the other side is parallel to the Y axis. Square-shaped unit constituent regions R, each centered on a lattice point O of the square lattice, are two-dimensionally arranged across multiple columns along the X axis and multiple rows along the Y axis. The XY coordinates of each unit constituent region R are defined by the center of gravity of the respective unit constituent region R. These center of gravity positions coincide with the lattice point O of the virtual square lattice. For example, only one modified refractive index area 15b is provided in each unit constituent region R. The modified refractive index area 15b has a planar shape that 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.

[0038] FIG. 4 is an enlarged view of the unit constituent region R. As shown in the figure, each modified refractive index area 15b has a center of gravity G. Here, the angle between the vector from lattice point O toward the center of gravity G and the X-axis is defined as γ(x, y). x indicates the position of the xth lattice point on the X-axis, and y indicates the position of the yth lattice point on the Y-axis. When the rotation angle γ is 0°, the direction of the vector connecting lattice point O and the center of gravity G coincides with the positive direction of the X-axis. Furthermore, the length of the vector connecting lattice point O and the center of gravity G is defined as r(x, y). In one example, r(x, y) is constant throughout the phase modulation layer 15, regardless of x and y.

[0039] The center of gravity G of each modified refractive index area 15b is positioned relative to the corresponding lattice point O at a position corresponding to the phase modulation amount of a predetermined phase distribution. That is, as shown in FIG. 3 , the direction of the vector connecting the lattice point O and the center of gravity G, in other words, the rotation angle γ of the center of gravity G of the modified refractive index area 15b around the lattice point O, is individually set for each lattice point O according to the phase distribution φ(x, y) corresponding to the desired shape of the emitted light. In the present disclosure, this arrangement of the center of gravity G is referred to as the first arrangement. 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 γ(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 recommended to apply an iterative algorithm such as the Gerchberg-Saxton (GS) method, which is commonly used in calculations for hologram generation. In this case, it is possible to improve the reproducibility of the beam pattern.

[0040] FIG. 5 is a plan view showing an example of the phase distribution of the phase modulation layer 15. The predetermined phase distribution of the phase modulation layer 15 may have a region 151 on one side of the optical axis 21 in one direction (the X-axis direction in the illustrated example) and a region 152 on the other side of the optical axis 21 in the same direction. In this case, the optical axis 21 is located between the region 151 and the region 152. The distance from the region 151 to the optical axis 21 is equal to the distance from the region 152 to the optical axis 21. In other words, the planar shapes of the region 151 and the region 152 are symmetrical with respect to a line passing through the optical axis 21 and extending in the Y-axis direction. The optical axis 21 is the central axis of light emitted from the light-emitting device 1, and is typically the center line of the light-emitting device 1 along the Z-axis direction. The regions 151 and 152 have planar shapes such as rectangular shapes and extend in a direction intersecting the X-axis direction (the Y-axis direction in the illustrated example). The longitudinal direction of the region 151 is parallel to the longitudinal direction of the region 152. A gap 22 including the optical axis 21 is provided between the region 151 and the region 152. The width of the gap 22 in the X-axis direction is arbitrary.

[0041] Regions 151 and 152 include a one-dimensional lens pattern whose phase changes in the arrangement direction of regions 151 and 152, i.e., in the X-axis direction. FIG. 6 is a diagram showing how beams 241 and 242 are emitted from regions 151 and 152 shown in FIG. 5 . Beam 241 (first beam), which is +1st-order light, is emitted from region 151. Beam 242 (second beam), which is +1st-order light, is emitted from region 152. Beams 241 and 242 cross each other at a first position 25 and then separate. First position 25 is defined as the center position in the XZ plane of region 26 (shown by dots in the figure) where beams 241 and 242 overlap. If the width of region 151 in the X-axis direction is equal to the width of region 152 in the same direction, region 26 will have a diamond shape when viewed from the Y-axis direction. Within the region 26, a focused spot 261 is formed that extends in the light emission direction and is centered at the first position 25. The first position 25 may be located on the optical axis 21 or away from the optical axis 21. In Fig. 6, the greater the width of the gap 22 in the X-axis direction, the farther the first position 25 is from the phase modulation layer 15.

[0042] FIG. 7 is a plan view showing another example of the phase distribution of the phase modulation layer 15. In the example shown in FIG. 7, there is no gap between the region 151 and the region 152, and the region 151 and the region 152 are in contact with each other. The optical axis 21 is located on the boundary line between the region 151 and the region 152. FIG. 8 is a diagram showing how the beams 241 and 242 are emitted from the regions 151 and 152, respectively, shown in FIG. 7. In this example, the end of the region 26 is close to the phase modulation layer 15. Therefore, the first position 25 is closer to the phase modulation layer 15 than in the case of FIG. 6.

[0043] Phase distribution φ in the X-axis direction of a one-dimensional lens pattern ｎｏｒｍ (x) is expressed, for example, by the following mathematical formula (3): Formula (3) includes a coordinate x in the X-axis direction with the optical axis 21 as the origin, a distance L from the optical axis 21 to the edge of the one-dimensional lens pattern, a positive real number α, and a positive real number β.

[0044] FIG. 9 is a graph showing the above equation (3). In FIG. 9, the vertical axis represents the phase value, and the horizontal axis represents the coordinate x. In this example, the distance L = 0.5, and the real number β = 1.0. Curves G11 to G18 are shown in the figure. Curves G11 to G18 represent the cases where the real number α is 0.1, 0.25, 0.5, 0.8, 1.0, 1.2, 1.5, and 2.0, respectively. As shown in the figure, when the real number α is less than 1.0, the lens pattern is concave between the optical axis 21 and the edge of the lens pattern. When the real number α is 1.0, the phase value is proportional to x, and the lens pattern is flat between the optical axis 21 and the edge of the lens pattern, forming a shape equivalent to a triangular prism. When the real number α is greater than 1.0 and less than 2.0, the lens pattern is convex between the optical axis 21 and the edge of the lens pattern. When the real number α is 2.0, the lens pattern corresponds to a conventional focusing lens. When the real number α is 2.0 or greater, the beams 241 and 242 intersect at the first position 25 and then diverge without separating from each other.

[0045] 10 to 12 show the phase distribution φ ｎｏｒｍ10 shows a visualization of (x). In the figure, the magnitude of the phase is expressed by the shade of color, with darker colors indicating closer to 0 (rad) and lighter colors indicating closer to 2π (rad). Fig. 10 shows the case where the real number α is 2.0, Fig. 11 shows the case where the real number α is 1.0, and Fig. 12 shows the case where the real number α is 0.5.

[0046] 13 to 15 show the phase distribution φ ｎｏｒｍ 13A to 15B are diagrams showing the results of a simulation of the shape of the focused spot 261 obtained by (x). In FIGS. 13 to 15A, (a) shows a cross section of the focused spot 261 along the XY plane, (b) shows a cross section of the focused spot 261 along the XZ plane, and (c) shows a cross section of the focused spot 261 along the YZ plane. FIG. 13 shows the case where the real number α is 2.0, FIG. 14 shows the case where the real number α is 1.0, and FIG. 15 shows the case where the real number α is 0.5. In this simulation, the wavelength is 0.9 μm, the size of the calculation region is 500 μm square, the size of the modulation region of the phase modulation layer 15 is 200 μm square, and the calculation interval is 0.45 μm (half the wavelength) in both the X-axis and Y-axis directions.

[0047] In one embodiment, the real number α is 1.0 and the real number β is greater than or equal to 2.0 and less than or equal to 20. In another embodiment, the real number α is greater than or equal to 0.8 and less than or equal to 1.2 and the real number β is greater than or equal to 2.0 and less than or equal to 10. In yet another embodiment, the real number α is less than or equal to 0.5 and the real number β is greater than or equal to 5.0 and less than or equal to 20.

[0048] 16 is a diagram showing how beams 241 to 244 are emitted from the phase modulation layer 15 according to yet another example of the phase distribution of the phase modulation layer 15. In this example, in regions 151 and 152, another one-dimensional lens pattern whose phase changes in the one direction (the X-axis direction in the illustrated example) is superimposed on the one-dimensional lens pattern. This other one-dimensional lens pattern causes beam 243 (third beam), which is +1st-order light separate from beam 241, to be emitted together with beam 241 from region 151 on one side of the optical axis 21. At the same time, beam 244 (fourth beam), which is +1st-order light separate from beam 242, to be emitted together with beam 242 from region 152 on the other side of the optical axis 21. Beams 243 and 244 intersect at a second position 27 different from the first position 25 and then separate. The second position 27 is defined as the center position of a region 28 (shown by dots in the figure) in the XZ plane where the beams 243 and 244 overlap. When the width of the region 151 in the X-axis direction is equal to the width of the region 152 in the same direction, the region 28 has a diamond shape when viewed from the Y-axis direction. A focused spot 281 is formed in the region 28, centered at the second position 27 and extending in the light emission direction. In this way, a plurality of focused spots 261, 281 may be formed by a predetermined phase pattern of the phase modulation layer 15.

[0049] When the predetermined phase pattern of the phase modulation layer 15 forms a plurality of focused spots 261, 281, the first positions 25 and the second positions 27 corresponding to the respective focused spots 261, 281 may be aligned on a common imaginary plane 30 perpendicular to the optical axis 21, as shown in part (a) of Fig. 17 . Alternatively, the first positions 25 and the second positions 27 may be distributed three-dimensionally (stereoscopically) as shown in part (b) of Fig. 17 . That is, the first positions 25 may be located on a first imaginary plane 31 perpendicular to the optical axis 21, and the second positions 27 may be located on a second imaginary plane 32 perpendicular to the optical axis 21 and different from the first imaginary plane 31.

[0050] 18 is a plan view showing yet another example of the phase distribution of the phase modulation layer 15. The predetermined phase distribution of the phase modulation layer 15 may have an annular region 153 around the optical axis 21. In this case, the optical axis 21 is surrounded by the region 153. In one example, the optical axis 21 is located at the center of the region 153. A circular opening 23 including the optical axis 21 is provided inside the region 153. The radius of the opening 23 may have any size.

[0051] Region 153 includes a two-dimensional lens pattern whose phase changes in two mutually orthogonal directions (X-axis direction and Y-axis direction in the illustrated example). FIG. 19 is a diagram showing how beam 245 is emitted from region 153 shown in FIG. 18 , and schematically shows a cross section including optical axis 21. An annular beam 245 (first beam) of +1st-order light is emitted from region 153. The beam 245 first contracts in diameter at first position 33 and then expands into an annular shape. First position 33 is defined as the center position of region 34 where multiple elements of beam 245 emitted from each position of region 153 overlap each other. Region 34 has a biconical shape. A focused spot 341 is formed within region 34, centered at first position 33 and extending in the light emission direction. First position 33 may be located on optical axis 21 or away from optical axis 21. In FIG. 19, the first position 33 becomes farther from the phase modulation layer 15 as the radius of the opening 23 increases.

[0052] 20 is a plan view showing another example of the phase distribution of the phase modulation layer 15. In the example shown in FIG. 20, the region 153 does not have an opening 23, and the region 153 has a circular shape. The optical axis 21 is at the center of the region 153 and is included in the region 153. FIG. 21 is a diagram showing how a beam 245 is emitted from the region 153 shown in FIG. 20. In this example, the end of the region 34 is close to the phase modulation layer 15. Therefore, the first position 33 is closer to the phase modulation layer 15 than in the case of FIG. 19.

[0053] Phase distribution φ in the radial direction of a two-dimensional lens pattern ｎｏｒｍ (r) is expressed, for example, by the following mathematical formula (4): Formula (4) includes the distance r from the optical axis 21, the distance L from the optical axis 21 to the edge of the two-dimensional lens pattern, a positive real number α, and a positive real number β.

[0054] If the horizontal axis of FIG. 9 is replaced with r, a graph showing the above formula (4) is obtained. When the real number α is less than 1.0, the lens pattern is concave between the optical axis 21 and the edge of the lens pattern. When the real number α is 1.0, the phase value is proportional to r, and the lens pattern is triangular pyramidal. That is, an axicon lens is realized by a lens pattern with a predetermined phase distribution, and the beam 245 at that time is a Bessel beam. When the real number α is greater than 1.0 and less than 2.0, the lens pattern is convex between the optical axis 21 and the edge of the lens pattern. When the real number α is 2.0, the lens pattern corresponds to a conventional focusing lens. When the real number α is 2.0 or greater, the beam 245 converges at the first position 33 and then expands into a circular shape without an aperture.

[0055] 22 to 24 show the phase distribution φ ｎｏｒｍ 22 shows a visualization of (r). In the figure, the magnitude of the phase is expressed by the shade of color, with darker colors being closer to 0 (rad) and lighter colors being closer to 2π (rad). FIG. 22 shows the case where the real number α is 2.0. FIG. 23 shows the case where the real number α is 1.0. FIG. 24 shows the case where the real number α is 0.5.

[0056] 25 to 27 show the phase distribution φ ｎｏｒｍ 25A to 27B are diagrams showing the results of a simulation of the shape of the focused spot 341 obtained by (r). In FIGS. 25 to 27A, (a) shows a cross section of the focused spot 341 along the XY plane, (b) shows a cross section of the focused spot 341 along the XZ plane, and (c) shows a cross section of the focused spot 341 along the YZ plane. Also, FIG. 25 shows the case where the real number α is 2.0, FIG. 26 shows the case where the real number α is 1.0, and FIG. 27 shows the case where the real number α is 0.5. In this simulation, the wavelength, the size of the calculation region, the size of the modulation region of the phase modulation layer 15, and the calculation interval are the same as those in FIGS. 13 to 15. In these FIGS. 25 to 27B, the light intensity is represented by shades of color, with the lighter the color, the greater the light intensity.

[0057] In one embodiment, the real number α is less than or equal to 1.2. In another embodiment, the real number α is greater than or equal to 0.5 and less than or equal to 1.2, and the real number β is greater than or equal to 2.0 and less than or equal to 20. In yet another embodiment, the real number α is greater than or equal to 0.1 and less than or equal to 0.25, and the real number β is greater than or equal to 5.0 and less than or equal to 50.

[0058] FIG. 28 shows how beams 245 and 246 are emitted from the phase modulation layer 15, based on yet another example of the phase distribution of the phase modulation layer 15. In this example, in region 153, another two-dimensional lens pattern whose phase changes in the two directions (X-axis direction and Y-axis direction in the illustrated example) is superimposed on the two-dimensional lens pattern. This other two-dimensional lens pattern causes beam 246 (second beam), which is a +1st-order light separate from beam 245, to be emitted from region 153 together with beam 245. Beam 246 first contracts in diameter at second position 35, which is different from first position 33, and then expands in diameter into an annular shape. Second position 35 is defined as the center position of region 36, where multiple elements of beam 246 emitted from each position in region 153 overlap each other. Region 36 has a biconical shape. Within region 36, a focused spot 361 is formed, centered at second position 35 and extending in the light emission direction. In this way, a plurality of focused light spots 341 and 361 may be formed by a predetermined phase pattern of the phase modulation layer 15 .

[0059] When the predetermined phase pattern of the phase modulation layer 15 forms a plurality of focused spots 341, 361, the first positions 33 and the second positions 35 corresponding to the respective focused spots 341, 361 may be aligned on a common imaginary plane 30 perpendicular to the optical axis 21, similar to the first positions 25 and the second positions 27 shown in part (a) of Fig. 17 . Alternatively, the first positions 33 and the second positions 35 may be distributed three-dimensionally (stereoscopically) similar to the first positions 25 and the second positions 27 shown in part (b) of Fig. 17 . That is, the first positions 33 may be located on a first imaginary plane 31 perpendicular to the optical axis 21, and the second positions 35 may be located on a second imaginary plane 32 perpendicular to the optical axis 21 and different from the first imaginary plane 31.

[0060] The effects obtained by the light-emitting device 1 according to the present embodiment described above will now be described. In the light-emitting device 1 of the present embodiment, the center of gravity G of each modified refractive index area 15b is disposed at a relative position corresponding to the phase modulation amount of a predetermined phase distribution with respect to the corresponding lattice point O of a virtual square lattice. With this structure, a so-called Si-iPM laser can generate an optical image of any shape.

[0061] Additionally, in the light-emitting device 1, beams 241 and 242 that are phase-modulated by a one-dimensional lens pattern are emitted from regions 151 and 152 located on both sides of the optical axis 21 in one direction. The beam 241 emitted from region 151 on one side of the optical axis 21 and the beam 242 emitted from region 152 on the other side of the optical axis 21 intersect with each other and then separate. When the beams 241 and 242 intersect, a focused spot 261 formed by the beams 241 and 242 extends over a wide range along the light-emitting direction. Alternatively, in the light-emitting device 1, a beam 245 that is phase-modulated by a two-dimensional lens pattern is emitted from region 153 located around the optical axis 21. The beam 245 emitted from region 153 first contracts in diameter and then expands in diameter into an annular shape. When the beam 245 contracts in diameter, a focused spot 341 formed by the beam 245 extends over a wide range along the light-emitting direction. That is, according to the light-emitting device 1 of this embodiment, the focused spot extends over a wide range along the light emission direction, in other words, the focal depth can be increased, so that even if the distance between the light-emitting device 1 and the target to be irradiated varies, the light can be converged on the target to be irradiated regardless of the variation.

[0062] Fig. 29 is a schematic diagram for comparing the manner of light collection. Part (a) of Fig. 29 shows the manner of light collection by a conventional lens pattern. Part (b) of Fig. 29 shows the manner of light collection by the lens pattern of this embodiment. As shown in part (a), the depth of focus DF is small when light is collected by the conventional lens pattern. In contrast, the depth of focus DF is extremely large when light is collected by the lens pattern of this embodiment. In this way, the light-emitting device 1 of this embodiment can achieve a deep depth of focus.

[0063] The one-dimensional lens pattern may be expressed by the above-mentioned formula (3). In this case, a one-dimensional lens pattern in which beam 241 and beam 242 intersect with each other and then separate can be preferably realized. The two-dimensional lens pattern may be expressed by the above-mentioned formula (4). In this case, a two-dimensional lens pattern in which beam 245 first contracts in diameter and then expands in diameter in an annular shape can be preferably realized.

[0064] When the predetermined phase distribution includes a one-dimensional lens pattern, as described above, the predetermined phase distribution may have a gap 22 including the optical axis 21 between the region 151 on one side of the optical axis 21 and the region 152 on the other side of the optical axis 21. In this case, the first position 25 where the beams 241 and 242 intersect can be controlled by the size of the gap 22. Therefore, the position of the focused spot 261 in the light emission direction can be set arbitrarily. When the predetermined phase distribution includes a two-dimensional lens pattern, as described above, the shape of the region 153 may have an opening 23 including the optical axis 21. In this case, the first position 33 where the beam 245 contracts in diameter can be controlled by the size of the opening 23. Therefore, the position of the focused spot 341 in the light emission direction can be set arbitrarily.

[0065] When the predetermined phase distribution includes a one-dimensional lens pattern, as described above, another one-dimensional lens pattern whose phase changes in one direction may be superimposed on the one-dimensional lens pattern in regions 151 and 152. This other one-dimensional lens pattern may cause a beam 243 separate from beam 241 to be emitted from region 151 on one side of optical axis 21, and a beam 244 separate from beam 242 to be emitted from region 152 on the other side of optical axis 21. Then, beam 243 and beam 244 may intersect and then separate at a second position 27 different from first position 25. In this case, multiple focused spots 261 and 281 can be simultaneously formed using a single light-emitting device 1. This allows the light source device to be more compact than when a light-emitting device is provided for each focused spot.

[0066] When the predetermined phase distribution includes a two-dimensional lens pattern, as described above, another two-dimensional lens pattern whose phase changes in two directions may be superimposed on the two-dimensional lens pattern in region 153. This other two-dimensional lens pattern may cause a beam 246 separate from beam 245 to be emitted from region 153. Then, beam 246 may be contracted in diameter at second position 35 different from first position 33 and then expand into an annular shape. In this case, a single light-emitting device 1 can be used to simultaneously form multiple focused spots 341, 361. This allows the light source device to be more compact than when a light-emitting device is provided for each focused spot.

[0067] Figure 30 shows the far-field pattern (FFP) obtained when a light-emitting device 1 having a predetermined phase distribution including a two-dimensional lens pattern was actually fabricated and multiple beams including beams 245 and 246 were emitted from the light-emitting device 1. In this example, two rows and three columns (six beams in total) of beams were emitted. The reason that 12 beams are observed in the far-field pattern is that six beams of first-order light are superimposed on six beams of -1st-order light. As shown in Figure 30, the light-emitting device 1 of this embodiment can effectively emit multiple beams that spread out in a circular shape.

[0068] 31 to 33 are diagrams showing near-field patterns (NFPs) of a beam emitted from the light-emitting device 1. (a) in FIG. 31 shows a near-field pattern on the surface of the light-emitting device 1 before oscillation. (b) and (c) in FIG. 31 , (a), (b), and (c) in FIG. 32 , and (a) and (b) in FIG. 33 show near-field patterns at positions z=50 μm, z=300 μm, z=550 μm, z=800 μm, z=950 μm, z=1050 μm, and z=1250 μm, respectively, with the surface of the light-emitting device 1 as the reference (z=0). As shown in FIGS. 31 to 33 , the light-emitting device 1 of this embodiment can form a focused spot over an extremely long range in the light emission direction. [Formation of Interference Fringes]

[0069] 6 or 8, when beams 241 and 242 cross each other and then separate to form focused spot 261, interference occurs in region 26 where beams 241 and 242 overlap, and a striped light image extending in the Y-axis direction may be observed. Similarly, when beam 245 temporarily contracts in diameter and then expands into an annular shape to form focused spot 341, as shown in FIG. 19 or 21, interference occurs in region 34 where portions of beam 245 overlap each other, and a concentric striped light image centered on optical axis 21 may be observed. These striped light images are used, for example, for three-dimensional shape measurement.

[0070] The above description assumes that only beams 241 and 242 (or beam 245), which are +1st-order light, are emitted from the light-emitting device 1. In an Si-iPM laser, -1st-order light is also generally emitted from the light-emitting device 1. Figure 34 is a diagram in which beams 247 and 248, which are -1st-order light, are added to Figure 8 . Beams 247 and 241 interfere with each other, and beams 248 and 242 interfere with each other. As a result, a striped optical image is generated not only in region 26 but also in regions 37 and 38 (shown by light dots in the figure). Similarly, Figure 35 is a diagram in which beam 249, which is -1st-order light, is added to Figure 21 . Because beams 249 and 245 interfere with each other, a striped optical image is generated not only in region 34 but also in region 39 (shown by light dots in the figure). In this way, the Si-iPM laser can expand the interference region compared to a conventional optical lens. 34, the region where the stripes are formed expands not only to region 26 but also to regions 37 and 38. Therefore, when light-emitting device 1 is used for three-dimensional measurement, it becomes possible to measure a wider range than with a normal optical lens.

[0071] The inventors set the real numbers α and β in formulas (3) and (4) to various values ​​and calculated striped light images through simulation. Fig. 36 is a diagram visualizing the difference in one-dimensional lens patterns depending on the real number β when the real number α is set to 1 in formula (3). In the diagram, the magnitude of the phase is expressed by the shade of color, with darker colors being closer to 0 (rad) and lighter colors being closer to 2π (rad).

[0072] Figures 37 to 48 are diagrams showing the striped light image that appears in region 26 of Figure 8 when the real numbers α and β in equation (3) representing the one-dimensional lens pattern are set to various values. In these Figures 37 to 48, light intensity is represented by shades of color, with lighter colors representing greater light intensity. Figures 37 to 42 each show light images at z = 500 μm, z = 1000 μm, z = 1500 μm, z = 2000 μm, z = 2500 μm, and z = 3000 μm, respectively, when the real number α is set to 1.0. These diagrams show that the number of stripes decreases when the real number β is 1.0 or less. Furthermore, as the real number β increases, the Z-axis distance Zmax at which interference occurs decreases; for example, when the real number β is greater than 20, the distance Zmax becomes 500 μm or less. Therefore, when the real number α is 1.0, in order to obtain clear stripes with little unevenness in brightness, the real number β should be 2.0 or more and 20 or less, more preferably 2.0 or more and 10 or less.

[0073] FIG. 43 shows the light image when the real number α is 1.2. FIG. 44 shows the light image when the real number α is 0.8. FIGS. 43 and 44 show light images at z = 500 μm, z = 1000 μm, z = 1500 μm, z = 2000 μm, z = 2500 μm, and z = 3000 μm, respectively, for real numbers β = 1.0, β = 2.0, β = 5.0, and β = 10. These figures reveal that when the real number α is 1.2, the light intensity is biased toward the optical axis due to the tendency for converging propagation caused by the curved wave, while when the real number α is 0.8, the light intensity is biased toward positions away from the optical axis due to the tendency for diverging propagation caused by the curved wave. Additionally, these figures reveal that, in order to obtain clear fringes with minimal brightness unevenness, when the real number α is 0.8 to 1.2, the real number β should be 2.0 to 10.

[0074] Figures 45 and 46 show the optical image when the real number α is set to 0.5. Figures 47 and 48 show the optical image when the real number α is set to 0.25. Figures 45 to 48 show the optical images at z = 500 μm, z = 1000 μm, z = 1500 μm, z = 2000 μm, z = 2500 μm, and z = 3000 μm, respectively, for real numbers β = 1.0, β = 2.0, β = 5.0, β = 10, β = 15, and β = 20. These figures show that when the real number α is 0.5 or less, the light intensity is biased toward positions away from the optical axis due to the divergent propagation tendency of the curved wave. In addition, it can be seen that strong fringes are formed at the edges of the optical image, but fine fringes are also formed inside them. In addition, it can be seen from these figures that when the real number α is 0.5 or less, the real number β should be 5.0 or more and 20 or less in order to obtain clear stripes with little unevenness in brightness.

[0075] Figures 49 to 56 are diagrams showing concentric striped light images that appear in region 34 of Figure 21 when the real numbers α and β in equation (4), which describes a two-dimensional lens pattern, are set to various values. In Figures 49 to 56, light intensity is represented by shades of color, with lighter colors representing greater light intensity. Figures 49 to 56 show light images when the real number α is set to 2.0, 1.5, 1.2, 1.0, 0.8, 0.5, 0.25, and 0.1, respectively. Figures 49 to 53 show light images at z = 500 μm, z = 1000 μm, z = 1500 μm, z = 2000 μm, z = 2500 μm, and z = 3000 μm, respectively, for real numbers β = 1.0, β = 2.0, β = 5.0, β = 10, and β = 20, respectively. 54 to 56 show optical images at z=500 μm, 1000 μm, 1500 μm, 2000 μm, 2500 μm, and 3000 μm, respectively, for real numbers β=1.0, β=2.0, β=5.0, β=10, β=20, and β=50. These figures show that in order to obtain clear stripes with little luminance unevenness, it is preferable for the real number α to be 1.2 or less. Alternatively, it is preferable for the real number α to be 0.5 to 1.2, and for the real number β to be 2.0 to 20. Alternatively, it is preferable for the real number α to be 0.1 to 0.25, and for the real number β to be 5.0 to 50.

[0076] The striped light image is used, for example, for three-dimensional shape measurement. Therefore, as long as the real numbers α and β are within the above ranges, even if the distance between the irradiation target and the light-emitting device 1 varies, three-dimensional shape measurement can be performed with high accuracy regardless of the variation. [Calculation of phase pattern]

[0077] A method for calculating a phase pattern in the phase modulation layer 15 will be described in detail below. FIG. 57 is a plan view showing an example in which a substantially periodic refractive index structure is applied to a specific region of the phase modulation layer 15. In the example shown in FIG. 57, a substantially periodic structure (e.g., the structure shown in FIG. 3) for emitting a desired optical image is formed inside the square inner region RIN. Meanwhile, a circular modified refractive index region 15b is arranged in the outer region ROUT surrounding the inner region RIN, in which the lattice point positions of the square lattice coincide with the center of gravity position. The lattice spacing a of the virtually set square lattice is identical inside the inner region RIN and the outer region ROUT. In the structure shown in FIG. 57, light is distributed also within the outer region ROUT, thereby suppressing the generation of high-frequency noise (so-called window function noise) caused by a sudden change in light intensity around the periphery of the inner region RIN. In addition, light leakage in a direction perpendicular to the thickness direction can be suppressed, which is expected to reduce the threshold current. The present invention is not limited to this example, and the substantially periodic structure for emitting a desired optical image (for example, the structure shown in FIG. 3) may be formed over the entire region of the phase modulation layer 15 .

[0078] In order to obtain a predetermined phase distribution including the one-dimensional or two-dimensional lens pattern described above, the rotation angle distribution γ(x, y) of the modified refractive index area 15b in the phase modulation layer 15 is determined by the following procedure.

[0079] As a first prerequisite, 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 M １ ×N １ pieces (M １ , N １ A virtual square lattice composed of unit constituent regions R (where R is an integer of 1 or more) is set on the XY plane.

[0080] The second prerequisite is that the coordinates (ξ, η, ζ) in the XYZ Cartesian coordinate system are expressed as spherical coordinates (r, θ ｒｏｔ ,θ ｔｉｌｔ ) satisfy the relationships shown in the following formulas (5) to (7). ｒｏｔ ,θ ｔｉｌｔ ) is the length r of the moving radius and the tilt angle θ from the Z axis, as shown in FIG. ｔｉｌｔ and the rotation angle θ from the X-axis specified on the XY plane ｒｏｔ and is defined by the spherical coordinates (r, θ ｒｏｔ ,θ ｔｉｌｔ 1 is a diagram illustrating a coordinate transformation from coordinates (ξ, η, ζ) in the XYZ Cartesian coordinate system to coordinates (ξ, η, ζ) in the XYZ Cartesian coordinate system. The coordinates (ξ, η, ζ) represent a designed optical image on a predetermined plane set in the XYZ Cartesian coordinate system, which is real space.

[0081] The light emitted from the light-emitting device 1 is reflected at an angle θ ｔｉｌｔ and θ ｒｏｔ The set of bright points facing the direction defined by the angle θ ｔｉｌｔ and θ ｒｏｔ is converted into a coordinate value kx and a coordinate value ky. The coordinate value kx is a normalized wave number defined by the following equation (8), and corresponds to the X axis. ｘ The coordinate value ky is a normalized wave number defined by the following equation (9), and corresponds to the Y axis and is also a coordinate value on the K axis. ｘ K perpendicular to the axis ｙ The normalized wave number is a wave number normalized by setting the wave number 2π / a, which corresponds to the lattice spacing of a virtual square lattice, to 1.0. ｘ axis and K ｙ In the wavenumber space defined by the axes, specific wavenumber ranges including the beam pattern corresponding to the optical image are each a square-shaped M ２ ×N ２ pieces (M ２ , N ２ is an integer greater than or equal to 1). ２ is an integer M １ Similarly, the integer N２ is an integer N １ The formulas (8) and (9) are disclosed in, for example, Non-Patent Document 2. a: lattice constant of a virtual square lattice λ: oscillation wavelength of the light-emitting device 1

[0082] Here, 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 or more N ２ The image area specified by the coordinate component x (an integer equal to or less than 0) in the X-axis direction is defined as the image area FR(kx, ky). １ -1 or less) and the coordinate component y (0 or more N １ A unit constituent region on the X-Y plane specified by kx, ky and k(kx, ky) is defined as unit constituent region R(x, y). The complex amplitude obtained by performing a two-dimensional inverse discrete Fourier transform on each image region FR(kx, ky) to the unit constituent region R(x, y) is defined as complex amplitude F(x, y). As a third precondition, the complex amplitude F(x, y) is given by the following equation (10), where j is the imaginary unit. When the amplitude term is A(x, y) and the phase term is φ(x, y), the complex amplitude F(x, y) is defined by the following equation (11). As a fourth precondition, the unit constituent region R(x, y) is defined by the s-axis and the t-axis. The s-axis and the t-axis are parallel to the X-axis and the Y-axis, respectively, and intersect at right angles at lattice point O(x, y), which is the center of the unit constituent region R(x, y).

[0083] 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 １is set to a common value in each of the unit constituent regions R. In addition, the angle formed by the line segment connecting the lattice point O(x, y) and the corresponding center of gravity G and the s-axis is defined as angle γ(x, y). The sixth condition is met by arranging the corresponding modified refractive index area 15b within the unit constituent region R(x, y) so that angle γ(x, y) satisfies the following relationship: γ(x, y) = C × φ(x, y) + B C: proportionality constant, for example 180° / π B: any constant, for example 0

[0084] Next, the M-point oscillation of the light-emitting device 1 will be described. For the light-emitting device 1 to achieve M-point oscillation, 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 should satisfy the condition λ = (√2)n × a. Figure 59 is a plan view showing the reciprocal lattice space related to the phase modulation layer of a light-emitting device that performs M-point oscillation. Point P in the figure represents a reciprocal lattice point. Arrow B1 in the figure represents the fundamental reciprocal lattice vector. Arrows K1, K2, K3, and K4 represent four in-plane wave vectors. Each of the in-plane wave vectors K1 to K4 has a wave number spread SP due to the rotation angle distribution γ(x, y).

[0085] 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 does not become 0, and the wave number in the in-plane direction cannot become 0 due to diffraction. Therefore, diffraction does not occur in the direction perpendicular to the plane (Z-axis direction). If this continues, the M-point oscillation light-emitting device 1 will not output not only zero-order light in the direction perpendicular to the plane (Z-axis direction), but also +1st-order light and -1st-order light in directions inclined with respect to the Z-axis direction.

[0086] In this embodiment, the M-point oscillation light-emitting device 1 is configured as follows to apply the following technique to the phase modulation layer 15, so that the zeroth-order light is not output, but a portion of the +1st-order light and the -1st-order light is output. That is, as shown in FIG. 60, a diffraction vector V1 having a certain magnitude and direction is added to the in-plane wave vectors K1 to K4. This causes the magnitude of at least one of the in-plane wave vectors K1 to K4 (in the figure, the in-plane wave vector K3) to be 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 a light line LL, which is a circular region with a radius of 2π / λ.

[0087] In FIG. 60, the in-plane wave vectors K1 to K4 shown by dashed lines represent the wave vectors before the addition of the diffraction vector V1. 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. Therefore, wave vectors whose magnitude falls within the light line LL have 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.

[0088] Next, we consider the magnitude and direction of the diffraction vector V1 to place at least one of the in-plane wave vectors K1 to K4 within the light line LL. The following equations (12) to (15) show the in-plane wave vectors K1 to K4 before the diffraction vector V1 is added. The spreads Δkx and Δky of the wave vectors satisfy the following formulas (16) and (17), respectively. ｍａｘ and the maximum value of the spread in the y-axis direction Δky ｍａｘ is defined by the angular spread of the optical image of the design.

[0089] When the diffraction vector V1 is expressed as in the following formula (18), the in-plane wave vectors K1 to K4 after the diffraction vector V1 is added are expressed as the following formulas (19) to (22).

[0090] In the formulas (19) to (22), if 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 (23) holds. That is, by adding the diffraction vector V1 that satisfies the formula (23), any of the in-plane wave vectors K1 to K4 falls within the light line LL, thereby outputting a part of the +1st-order light and the −1st-order light.

[0091] The size (radius) of the light line LL is set to 2π / λ for the following reason. Figure 61 is a diagram for schematically explaining the structure surrounding the light line LL. The figure 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. When light propagates through the device medium as shown in Figure 61, the magnitude of the wave vector Ka in the medium with refractive index 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).

[0092] In Figure 61, when the wave vector Ka and the Z axis form an angle θ, the length of the wave vector projected onto the plane, i.e., the in-plane wave vector Kb, is (2πn / λ) sin θ. 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. In this case, 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.

[0093] As an example of a specific method for adding the diffraction vector V1 to the in-plane wave vectors K1 to K4, the following method can be considered: １(x, y), the phase distribution φ 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. ２ (x, y) is the phase distribution for adding the diffraction vector V1 that satisfies the above equation (23).

[0094] FIG. 62 shows the phase distribution φ ２ 1 is a diagram conceptually illustrating an example of (x, y) in which 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 is π (rad), where the first phase value φ Ａ and a second phase value φ Ｂ and change by π. This arrangement of phase values ​​makes it possible to effectively 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). Therefore, the diffraction vector V1 exactly cancels out one of the in-plane wave vectors K1 to K4 in FIG. 11. Therefore, the axis of symmetry between the +1st-order light and the -1st-order light coincides with the Z direction, i.e., a direction perpendicular to the in-plane direction of the phase modulation layer 15. Generally, the angular distribution θ2(x, y) of the diffraction vector V is expressed as the dot product of the diffraction vector V(Vx, Vy) and the position vector r(x, y), and is given by the following equation: θ2(x, y) = V r = Vx x + Vy y Therefore, when V = V1, the phase values ​​are 0 and π when the position vector r(xa, ya) (x and y are both integers) is used. 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 falls within the range of the light line LL.

[0095] In the present embodiment, when the wavenumber spread based on the angular spread of the emitted light is contained in a circle of radius Δk centered at a certain point in wavenumber space, this can also be simply considered as follows: By adding a diffraction vector V1 to the four-directional in-plane wavenumber vectors K1 to K4, the magnitude of at least one of the four-directional in-plane wavenumber vectors K1 to K4 is made smaller than 2π / λ (light line LL). This can be considered to be the same as making the magnitude of at least one of the four-directional in-plane wavenumber vectors K1 to K4 smaller than the value ((2π / λ) - Δk) obtained by subtracting the wavenumber spread Δk from 2π / λ by adding a diffraction vector V1 to the four-directional in-plane wavenumber vectors K1 to K4.

[0096] FIG. 63 is a diagram conceptually illustrating the above-mentioned idea. A diffraction vector V1 is added to the in-plane wave vectors K1 to K4 excluding the wave number spread Δk. As shown in the figure, at this time, the magnitude of at least one of the in-plane wave vectors K1 to K4 is smaller than {(2π / λ)-Δk}. In FIG. 63, region LL2 is a circular region with a radius of {(2π / λ)-Δk}. In FIG. 63, the in-plane wave vectors K1 to K4 shown by dashed lines represent the state before the addition of the diffraction vector V1, while the in-plane wave vectors K1 to K4 shown by solid lines represent the state after the addition of the diffraction vector V1. Region LL2 corresponds to the total reflection condition that takes into account the wave number spread Δk. Therefore, wave vectors whose magnitude falls within region LL2 also propagate in the direction perpendicular to the plane (the Z-axis direction).

[0097] 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 (24) to (27) show the in-plane wave vectors K1 to K4 before the diffraction vector V1 is added.

[0098] Here, when the diffraction vector V1 is expressed as in the above-mentioned formula (18), the in-plane wave number vectors K1 to K4 after the diffraction vector V1 is added are expressed by the following formulas (28) to (31).

[0099] In formulas (28) to (31), 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 (32) holds. That is, by adding a diffraction vector V1 that satisfies formula (32), 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.

[0100] FIG. 64 is a plan view showing another embodiment of the phase modulation layer 15. FIG. 65 is a diagram showing the arrangement of modified refractive index areas 15b in the phase modulation layer 15 shown in FIG. 64. As shown in FIGS. 64 and 65, 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. Even in this case, the center of gravity G of each modified refractive index area 15b can be arranged at a relative position corresponding to the phase modulation amount of a predetermined phase distribution with respect to the corresponding lattice point O of a virtual square lattice. The straight line D passes through the lattice point O corresponding to each unit constituent region 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 of the square lattice (the X-axis) is ψ.

[0101] In this case, the tilt angle ψ is constant within the phase modulation layer 15. The tilt angle ψ satisfies 0°<ψ<90°, and in one example, ψ=45°. Alternatively, the tilt angle ψ satisfies 180°<ψ<270°, and in one example, ψ=225°. When the tilt angle ψ satisfies 0°<ψ<90° or 180°<ψ<270°, the straight line D extends from the first quadrant to the third quadrant of the coordinate plane defined by the X-axis and Y-axis. The tilt angle ψ satisfies 90°<ψ<180°, and in one example, ψ=135°. Alternatively, the tilt angle ψ satisfies 270°<ψ<360°, and in one example, ψ=315°. When the tilt angle ψ satisfies 90°<ψ<180° or 270°<ψ<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 tilt angle ψ is an angle excluding 0°, 90°, 180°, and 270°.

[0102] Here, the distance between the lattice point O and the center of gravity G is r(x, y). x is the position of the xth lattice point on the X axis. y is the position of the yth 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 angle is preferably 45°, 135°, 225°, or 315°. At these tilt angles, only two of the four wave vectors forming the standing wave at point M, for example, the in-plane wave vectors (±π / a, ±π / a), are phase-modulated, and the other two are not phase-modulated. Therefore, a stable standing wave can be formed.

[0103] 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 in accordance with the phase distribution φ(x, y) corresponding to the desired output light shape. In the present disclosure, this arrangement of the center of gravity G is referred to as the second arrangement. 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 distance r(x, y) is determined from the phase distribution φ(x, y) extracted from the complex amplitude distribution obtained by performing an inverse Fourier transform on the desired output light shape.

[0104] That is, when the phase φ(x, y) at a certain coordinate (x, y) is φ0, the distance r(x, y) is set to 0. When the phase φ(x, y) is π+φ0, the distance r(x, y) is set to the maximum value R0. When the phase φ(x, y) is -π+φ0, the distance r(x, y) is set to the minimum value -R0. For phases φ(x, y) in between, the distance r(x, y) is set so that r(x, y) = {φ(x, y) - φ0} × R0 / π. The initial phase φ0 can be set arbitrarily.

[0105] If the lattice spacing of a virtual square lattice is a, the maximum value R of r(x, y) falls within the range of the following equation (33), for example. When determining the complex amplitude distribution from a desired optical image, it is advisable to apply an iterative algorithm such as the GS method, which is commonly used in calculations for generating holograms. This makes it possible to improve the reproducibility of the beam pattern. In this second embodiment, a desired light output shape (such as the number and position of light-focusing points) can be obtained by determining the distribution of the distances r(x, y) of the modified refractive index regions 15b of the phase modulation layer 15. Under the same first to fourth preconditions as in the first embodiment, the phase modulation layer 15 is configured to satisfy the following condition. That is, the corresponding modified refractive index region 15b is disposed within the unit constituent region R(x, y) so that the distance r(x, y) from the lattice point O(x, y) to the center of gravity G of the corresponding modified refractive index region 15b satisfies the following relationship: r(x, y) = C × (φ(x, y) - φ0), where C is a proportionality constant, such as R0 / π, and φ0 is an arbitrary constant, such as 0. To obtain a desired light output shape, the light output shape may be subjected to an inverse Fourier transform, and a distribution of the distances r(x, y) corresponding to the phase φ(x, y) of the complex amplitude may be imparted to the multiple modified refractive index regions 15b. The phase φ(x, y) and the distance r(x, y) may be proportional to each other.

[0106] In this second embodiment, as in the first embodiment described above, 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.

[0107] In this second embodiment, by implementing the following innovation in the phase modulation layer 15 in a light-emitting device that oscillates at point M, the zeroth-order light is not output within the light line LL, and a portion of the +1st-order light and the −1st-order light is output. Specifically, as shown in FIG. 60 , a diffraction vector V1 having a certain magnitude and direction is added to the in-plane wave vectors K1 to K4. This makes the magnitude of at least one of the in-plane wave vectors K1 to K4 smaller than 2π / λ. In other words, after the diffraction vector V1 is added, at least one of the in-plane wave vectors K1 to K4 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 (23), one of the in-plane wave vectors K1 to K4 is contained within the light line LL, and a portion of the +1st-order light and the −1st-order light is output.

[0108] 63, a diffraction vector V1 is added to the four-directional in-plane wave vectors K1 to K4 minus the wave number spread Δk, i.e., the four-directional in-plane wave vectors in an M-point oscillation square lattice PCSEL. This allows the magnitude of at least one of the four directional in-plane wave vectors K1 to K4 to be smaller than the value ((2π / λ)-Δk) obtained by subtracting the wave number spread Δk from 2π / λ. That is, by adding a diffraction vector V1 that satisfies the above-described formula (32), any one of the in-plane wave vectors K1 to K4 falls within region LL2, and a portion of the +1st-order light and a portion of the −1st-order light are output.

[0109] Here, a detailed description will be given of the design of the phase modulation layer 15 for condensing and emitting light from the light-emitting device 1. [Single Converged Spot Type (A)]

[0110] A method for designing the phase modulation layer 15 for forming a single focused spot by the light emitting device 1 itself will be described. First, the lens pattern φ Ｌ (x, y) is designed. At this time, the lens pattern φ Ｌ The lens pattern φ is set so that only the area including (x, y), that is, the areas 151 and 152 in FIGS. 5 and 7 or the area 153 in FIGS. 18 and 20, contributes to the formation of the focused spot. ＬDesign (x, y).

[0111] FIG. 66 shows such a lens pattern φ Ｌ This is a conceptual diagram of an iterative algorithm used in the design of (x, y). This iterative algorithm is based on the GS method. First, a target amplitude distribution is calculated from the square root of a target intensity distribution (beam pattern) on an infinitely distant screen (Process A1). At this time, the phase distribution is set to random, and a complex amplitude distribution composed of the target amplitude distribution and a random or non-constant phase distribution is used as the initial condition. Next, an inverse Fourier transform is performed on this complex amplitude distribution (Process A2). As a result, a complex amplitude distribution in the phase modulation layer 15 is obtained (Process A3).

[0112] Next, the amplitude distribution of the complex amplitude distribution in the phase modulation layer 15, i.e., r(x, y), and the phase distribution, i.e., the rotation angle distribution φ(x, y), are each replaced with a target distribution. For example, the amplitude distribution is replaced with a target distribution that is constant in both regions 151 and 152 (or region 153) and regions other than regions 151 and 152 (or region 153). At the same time, the phase distribution is replaced with a target distribution that maintains its original value in regions 151 and 152 (or region 153) and is constant in regions other than regions 151 and 152 (or region 153) (process A4).

[0113] Next, a Fourier transform is performed on the complex amplitude distribution consisting of the amplitude distribution and phase distribution after the replacement (process A5). As a result, a complex amplitude distribution on an infinitely far screen is obtained (process A6). Of this complex amplitude distribution, the amplitude distribution is replaced with a target amplitude distribution (beam pattern), while the phase distribution remains unchanged (process A7). By performing an inverse Fourier transform on the complex amplitude distribution consisting of these amplitude distributions and phase distributions (process A2), the complex amplitude distribution in the phase modulation layer 15 is obtained again (process A3). The above processes A2 to A7 are repeated a sufficient number of times. Then, the phase distribution of the complex amplitude distribution finally obtained in the phase modulation layer 15 is used to arrange the modified refractive index areas 15b in the phase modulation layer 15.

[0114] With this method, an optical image including a single focused spot can be completed from the distribution of the modified refractive index areas 15b in only areas 151 and 152 (or area 153). In this case, the phase distribution is constant in areas other than areas 151 and 152 (or area 153), but the modified refractive index areas 15b in areas other than areas 151 and 152 (or area 153) do not contribute to the optical image. Therefore, the positions of the centers of gravity G of the multiple modified refractive index areas 15b in areas other than areas 151 and 152 (or area 153) may be located on lattice point O of a virtual square lattice. Alternatively, the positions of the centers of gravity G of the multiple modified refractive index areas 15b in areas other than areas 151 and 152 (or area 153) may be located away from lattice point O of the virtual square lattice and at a constant rotation angle φ around lattice point O.

[0115] FIG. 67 shows the lens pattern φ Ｌ 1 is a diagram conceptually illustrating processing after designing (x, y). Ｌ After designing (x, y), the lens pattern φ is Ｌ (x, y) and the phase distribution φ for the diffraction vector V ２ The sum φ with (x, y) Ｌ +φ ２ Calculate the sum φ Ｌ +φ ２ Alternatively, a mask process may be performed on regions other than the regions 151 and 152 (or the region 153) to forcibly set the phase values ​​of the regions other than the regions 151 and 152 (or the region 153) to a constant value, and the resulting phase distribution φ′(x, y) may be used as the final predetermined phase distribution.

[0116] Fig. 68 is a partially enlarged view of regions 151 and 152 (or region 153) of the predetermined phase distribution φ(x, y) or the phase distribution φ'(x, y) after masking. When this phase pattern is viewed locally, it appears at first glance that a first phase value and a second phase value different from the first phase value are arranged in a checkerboard pattern, similar to Fig. 62. For example, with such a phase pattern, the diffraction vector V1 described above can be added to the in-plane wave vectors K1 to K4. [Single Focused Spot Type (B)]

[0117] Next, another method for designing the phase modulation layer 15 for forming a single focused spot 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. 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, i.e., the direction perpendicular to the in-plane direction of the phase modulation layer 15.

[0118] In another single-focus design, the diffraction vector V1 is changed so that the lengths of the in-plane wave vectors K1 to K4 are all 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 spaced apart 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. Such a diffraction vector V1 is obtained by adding a non-zero vector (dVx, dVy) to the diffraction vector V1 = (±π / a, ±π / a). That is, the diffraction vector V1 is set to V1 = ±(π / a)(1 + dVx, 1 + dVy).

[0119] The component of the phase distribution corresponding to the non-zero vector (dVx, dVy) is the lens pattern φ Ｌ Together with (x, y), this constitutes an element for focusing the emitted light into one focused spot in the phase distribution φ(x, y). Even if the axis of symmetry between the +1st order light and the -1st order light is tilted from the Z direction, the +1st order light forms a focused spot on the light-emitting surface side of the light-emitting device 1. In this case, the -1st order light diverges and does not form a focused spot. Therefore, this design makes it possible to preferably form one focused spot. [Multiple focused spot type]

[0120] Next, a description will be given of one method for designing the phase modulation layer 15 for forming a plurality of focused spots by a single light-emitting device 1 itself. Fig. 69 is a diagram conceptually showing this design method. As shown in Fig. 69, in this design method, a hologram phase distribution φ for emitting outgoing light in at least two directions is used. Ｈ (x, y) and a lens pattern φ for forming a focused spot Ｌ (x, y) are combined. The combined phase distribution is then applied to a lens pattern φ for forming at least two focused spots. Ｌ２ (x, y). Then, this phase distribution φ Ｌ２ (x, y) and the phase distribution φ for the diffraction vector V ２ 67, a mask process may be performed on the regions other than the regions 151 and 152 (or the region 153) to forcibly set the phase values ​​of the regions other than the regions 151 and 152 (or the region 153) to a constant value, and the obtained phase distribution may be used as the final predetermined phase distribution.

[0121] At least two focused spots may be located on the same imaginary plane perpendicular to the Z axis (see FIG. 17(a)). In this case, the hologram phase distribution φ Ｈ (x, y) and lens pattern φ Ｌ As an example of a method for synthesizing (x, y) and (x, y), the hologram phase distribution φ Ｈ (x, y) phase value and lens pattern φ Ｌ The sum φ of the phase value of (x, y) Ｈ (x, y) + φ Ｌ There is a method of taking (x, y). At least two focused spots may be located on multiple imaginary planes that are perpendicular to the z-axis and have different z-coordinates (see FIG. 17(b)). In this case, the hologram phase distribution φ Ｈ (x, y) and lens pattern φ Ｌ (x, y) can be synthesized using the following methods. Ｈ (x, y) phase value and lens pattern φ Ｌ The sum φ of the phase value of (x, y)Ｈ (x, y) + φ Ｌ The synthetic phase distribution φs is (x, y) １ (x, y) to 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) to φs ｎ (x, y) are combined with each other. The combined phase distribution is then calculated using a lens pattern φ for focusing the output light into at least two focusing spots. Ｌ２ Let (x, y).

[0122] One method is to use the synthetic phase distribution φs １ (x, y) to φs ｎ This is a method of dividing each of (x, y) into a real part and an imaginary part, and performing 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 70. However, Figure 70 shows the case where n=2. First, as shown below, the synthetic phase distribution φs １ (x, y) to φs ｎ Each of (x, y) is divided into a real part and an imaginary part (processes 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) to φs ｎ The real parts and imaginary parts of (x, y) are added together as follows (steps 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(φsｎ Then, the real part Re and the imaginary part Im are written in polar form as follows (step B5 in the figure): Re + j·Im = A·exp(j·φ Ｌ２ ) (A: amplitude, φ Ｌ２ : argument) From the above calculation, the composite phase φ at each coordinate (x, y) Ｌ２ , i.e., the lens pattern φ for forming at least two focused spots Ｌ２ (x, y) is obtained (process B6 in the figure).

[0123] Another method is to calculate the composite phase distribution φs １ (x, y) to φs ｎ This method (hereinafter referred to as the second method) involves randomly selecting phase values ​​from (x, y) in a two-dimensional space and superimposing the selected phase values. In this method, the composite phase distribution φs １ (x, y) to φs ｎ (x, y) and select a phase value from only one of the two or more synthetic phase distributions φs １ (x, y) to φs ｎ The phase values ​​of (x, y) are set so as not to overlap. Figure 71 shows an example of a random pattern used in this method. However, in Figure 71, it is assumed that n = 2. Figure 71(a) shows the composite phase distribution φs １ (x, y) is applied to the random pattern 50A. Figure 71(b) shows the composite 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. 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. Here, the white regions are regions 52 where a phase value is selected (hereinafter referred to as selected regions), and the black regions are regions 53 where a phase value is not selected (hereinafter referred to as 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 the (x, y) coordinates. ２From the coordinates (x, y), a phase value of the coordinates (x, y) corresponding to the selected region 52 of the random pattern 50B is selected. Comparing the random patterns 50A and 50B, the selected regions 52 of the random patterns 50A and 50B are distributed complementarily. That is, the selected regions 52 in the random pattern 50A are always non-selected regions 53 in the random pattern 50B. The non-selected regions 53 in the random pattern 50A are always selected regions 52 in the random pattern 50B. The selected regions 52 are distributed two-dimensionally and randomly on the xy plane. The number of selected regions 52 in the random pattern 50A, i.e., the composite phase distribution φs １ The number of phase values ​​selected from (x, y) is the number of selected regions 52 in the random pattern 50B, i.e., the composite phase distribution φs ２ This may be equal to the number of phase values ​​selected from (x, y), or it may be slightly different.

[0124] A method for creating the random patterns 50A and 50B described above may involve, for example, assigning a value to each region from random numbers between 0 and 1, and then designating the region where the value is equal to or greater than 0 and less than 1 / 2 as the selected region 52 for the random pattern 50A, and the region where the value is equal to or greater than 1 / 2 and less than 1 as the selected region 52 for the random pattern 50B, etc. The Rand function of the numerical calculation software MATLAB (registered trademark), for example, can be used to create the random number distribution.

[0125] In the above FIG. 71, 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 selected region 52 of the random pattern corresponding to (x, y) is distributed complementarily. That is, the composite phase distribution φs １ The selected region 52 in the random pattern corresponding to (x, y) is the region of the other synthetic phase distribution φs ２ (x, y) and φs ３In each random pattern corresponding to (x, y), there is always a non-selected region 53. ２ The selected region 52 in the random pattern corresponding to (x, y) is the region of the other 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. ３ The selected region 52 in the random pattern corresponding to (x, y) is the region of the other 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 random numbers 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 selected region 52 of the random pattern corresponding to (x, y) is defined as the region that is equal to or greater than 1 / 3 and less than 2 / 3, and the composite phase distribution φs ２ The selected region 52 of the random pattern corresponding to (x, y) is defined as the region between 2 / 3 and 1, and the region is defined as the composite phase distribution φs ３ It is preferable to use a random pattern selection area 52 corresponding to (x, y). When n is 4 or more, a random pattern can be created by a method similar to the above method.

[0126] According to each of the above methods, the hologram phase distribution φ Ｈ The +1st-order light can be emitted in at least two directions using (x, y). Therefore, at least two focused spots can be formed using only the +1st-order light. [Configuration of the three-dimensional measurement system]

[0127] FIG. 72 is a schematic diagram showing the configuration of a three-dimensional measurement system 101. As shown in the figure, the three-dimensional measurement system 101 includes a light source device 102, multiple (e.g., a pair of) image capture units 103, and a measurement unit 104. The light source device 102 includes the light-emitting device 1 of 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 or three dimensions. If the irradiation range of the measurement light 105 is sufficiently wide compared to the measurement range of the measurement object SA, the stage 106 may be omitted. The measurement light 105 emitted from the light source device 102 forms a striped light image on the surface of the measurement object SA.

[0128] The imaging unit 103 is configured by a device that has sensitivity to the measurement light 105 emitted from the light source device 102. For example, a CCD (Charge Coupled Device) camera, a CMOS (Complementary MOS) camera, or other two-dimensional image sensors can be used as the imaging unit 103. 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.

[0129] The measurement unit 104 is configured by a computer system including, for example, a processor, a memory, etc. The measurement unit 104 executes various control functions using the processor. Examples of computer systems 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). The measurement unit 104 is communicably connected to the image capture unit 103 and performs three-dimensional shape measurement of the measurement object SA based on signals input from the image capture unit 103. In this embodiment, the measurement unit 104 measures the three-dimensional shape of the measurement object SA based on a phase shift method using a striped light image.

[0130] As described above, the light source device 102 included in the three-dimensional measurement system 101 of this embodiment can form a striped light image on the surface of the measurement object SA without using other optical elements such as lenses. Such a striped light image can be suitably used in the three-dimensional measurement system 101. In addition, the light-emitting device 1 included in these light source devices 102 can be significantly smaller than conventional light sources. Therefore, the light source device 102 can be placed in extremely small spaces. This allows the light source device 102 to be inserted into small spaces that were previously impossible, such as inside the body, such as the oral cavity or a body cavity, inside a tube, a gap in a wall, or a gap between furniture, equipment, etc. and the floor. This facilitates image diagnosis and examination in these spaces.

[0131] As described above, the light source device 102 of this embodiment focuses and emits light by adjusting the phase distribution φ(x, y) of the S-iPM laser, causing self-interference. Self-interference can be achieved not only by the S-iPM laser, but also by spatially modulating the phase of light using, for example, a phase-modulating spatial light modulator (SLM). However, the technical concepts of the method using an SLM and the method of this embodiment using an iPM laser are significantly different.

[0132] An SLM is originally designed to output modulated light in a direction intersecting the light modulation surface. In an 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 signal light in a direction intersecting the light emission surface. Γ-point oscillation S-iPM lasers have been studied in the past, but Γ-point oscillation S-iPM lasers emit zeroth order light in a direction perpendicular to the light emission surface. Since zeroth order light is not affected by the phase distribution φ(x, y), when light is emitted while being focused as in this embodiment, it becomes unnecessary light, i.e., noise. By oscillating an S-iPM laser at the M-point, it is possible to prevent the zeroth order light from being emitted in a direction perpendicular to the light emission surface. However, if an S-iPM laser is simply oscillated at the M-point, signal light such as +1st order light and -1st order light is also not emitted in a direction intersecting 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). This makes it possible for the signal light to be emitted in a direction that intersects with the light exit surface. This kind of innovation is not easily conceivable in methods that use SLMs.

[0133] The light-emitting device and light source apparatus according to the present disclosure are not limited to the above-described embodiments, and various other modifications are possible. For example, the above embodiments illustrate laser elements made of GaAs-based, InP-based, and nitride-based (particularly GaN-based) compound semiconductors. The present disclosure can be applied to laser elements made of various other semiconductor materials. The above embodiments describe an example in which an active layer provided on a semiconductor substrate common to the phase modulation layer serves as the light-emitting portion. 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, such a configuration can also achieve the same effects as the above-described embodiments.

[0134] In the light-emitting devices of the above embodiments, the modified refractive index areas of the phase modulation layer are arranged at relative positions corresponding to the phase modulation amount with respect to the lattice points of the square lattice, as shown in Figures 4 and 65. The configuration for achieving phase modulation is not limited to this. For example, phase modulation may be performed using the size of the modified refractive index area instead of the relative position, or the relative position and the size of the modified refractive index area may be changed simultaneously.

[0135] In the above embodiment, when the virtual lattice is a square lattice, the lattice spacing of the square lattice and the emission wavelength λ of the light-emitting unit satisfy the condition for M-point oscillation. When the virtual lattice is a triangular lattice, the lattice spacing of the triangular lattice and the emission wavelength λ of the light-emitting unit may satisfy the condition for J-point oscillation.

[0136] 1...light-emitting device, 10...semiconductor substrate, 10a...main surface, 10b...rear surface, 11, 13...cladding layer, 12...active layer, 14...contact layer, 15...phase modulation layer, 15a...basic layer, 15b...modified refractive index area, 16, 17...electrode, 17a...opening, 18...protective film, 19...anti-reflection film, 21...optical axis, 22...gap, 23...opening, 25...first position, 26, 28, 34, 36 to 39...areas, 27...second position, 30...imaginary plane, 31...first imaginary plane, 32...second imaginary plane, 33...first position, 35...second position, 50A, 50B...random pattern, 51...area, 52 ...selected region, 53...non-selected region, 101...three-dimensional measurement system, 102...light source device, 103...imaging unit, 104...measurement unit, 105...measurement light, 106...stage, 151, 152, 153...region, 241 to 249...beam, 261, 281, 341, 361...focused spot, B1...primitive reciprocal lattice vector, D...line, DF...depth of focus, G...center of gravity, K1 to K4, Ka...wave vector, Kb...in-plane wave vector, LL...light line, LL2...region, O...lattice point, R...unit constituent region, RIN...inner region, ROUT...outer region, SA...object to be measured, V1...diffraction vector.

Claims

1. A light-emitting device comprising: a light-emitting section; and 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 distributed two-dimensionally in a plane perpendicular to a thickness direction, wherein the centers of gravity of the plurality of modified refractive index areas are arranged at relative positions corresponding to a phase modulation amount of a predetermined phase distribution with respect to corresponding lattice points of a virtual lattice set in the plane, the predetermined phase distribution having areas on both sides of the optical axis in the one direction including an area including a one-dimensional lens pattern in which the phase changes in one direction, and the one-dimensional lens pattern causes a first beam emitted from an area of ​​the area on one side of the optical axis to intersect with a second beam emitted from an area of ​​the area on the other side of the optical axis at a first position and then separate.

2. The light-emitting device of claim 1, wherein the one-dimensional lens pattern is represented by the following formula (1), which includes a coordinate x in the one direction with the optical axis as the origin, a distance L from the optical axis to an edge of the one-dimensional lens pattern, a positive real number α, and a positive real number β.

3. The light-emitting device of claim 2, wherein the positive real number α is 1.0, and the positive real number β is greater than or equal to 2.0 and less than or equal to 20.

4. The light-emitting device of claim 2, wherein the positive real number α is greater than or equal to 0.8 and less than or equal to 1.2, and the positive real number β is greater than or equal to 2.0 and less than or equal to 10.

5. The light-emitting device of claim 2, wherein the positive real number α is 0.5 or less, and the positive real number β is 5.0 or more and 20 or less.

6. A light-emitting device according to any one of claims 1 to 5, wherein the predetermined phase distribution has a gap including the optical axis between a region on one side of the optical axis and a region on the other side of the optical axis.

7. A light-emitting device as claimed in any one of claims 1 to 6, wherein in the said region, another one-dimensional lens pattern whose phase changes in the said one direction is superimposed on the said one-dimensional lens pattern, and by the said another one-dimensional lens pattern, a third beam separate from the said first beam is emitted from the region on one side of the said optical axis, and a fourth beam separate from the said second beam is emitted from the region on the other side of the said optical axis, and the said third beam and the said fourth beam intersect with each other at a second position different from the said first position and then separate.

8. The light emitting device of claim 7, wherein the first location and the second location lie on a common imaginary plane perpendicular to the optical axis.

9. The light-emitting device of claim 7, wherein the first position is on a first imaginary plane perpendicular to the optical axis, and the second position is on a second imaginary plane perpendicular to the optical axis and different from the first imaginary plane.

10. A light-emitting device comprising: a light-emitting section; and a phase modulation layer optically coupled to the light-emitting section, the phase modulation layer including a basic layer and a plurality of modified refractive index areas having a refractive index different from that of the basic layer and distributed two-dimensionally in a plane perpendicular to the thickness direction, wherein the centers of gravity of the respective modified refractive index areas are arranged at relative positions corresponding to a phase modulation amount of a predetermined phase distribution with respect to corresponding lattice points of a virtual lattice set in the plane, the predetermined phase distribution having an area around the optical axis including a two-dimensional lens pattern in which the phase changes in two mutually perpendicular directions, and wherein the two-dimensional lens pattern causes a first beam emitted from the area to once contract in diameter at a first position and then expand in diameter into an annular shape.

11. The light-emitting device of claim 10, wherein the two-dimensional lens pattern is represented by the following mathematical formula (2) including a distance r from the optical axis, a distance L from the optical axis to an edge of the two-dimensional lens pattern, a positive real number α, and a positive real number β.

12. The light emitting device of claim 11, wherein the positive real number α is less than or equal to 1.

2.

13. The light-emitting device of claim 11, wherein the positive real number α is greater than or equal to 0.5 and less than or equal to 1.2, and the positive real number β is greater than or equal to 2.0 and less than or equal to 20.

14. The light-emitting device of claim 11, wherein the positive real number α is greater than or equal to 0.1 and less than or equal to 0.25, and the positive real number β is greater than or equal to 5.0 and less than or equal to 50.

15. A light-emitting device according to any one of claims 10 to 14, wherein the shape of the region has an opening that includes the optical axis.

16. A light-emitting device as described in any one of claims 10 to 15, wherein in the region, another two-dimensional lens pattern whose phase changes in the two directions is superimposed on the two-dimensional lens pattern, and a second beam separate from the first beam is emitted from the region by the other two-dimensional lens pattern, and the second beam once contracts in diameter at a second position different from the first position and then expands in an annular shape.

17. The light emitting device of claim 16, wherein the first location and the second location lie on a common imaginary plane perpendicular to the optical axis.

18. The light-emitting device of claim 16, wherein the first position is on a first imaginary plane perpendicular to the optical axis, and the second position is on a second imaginary plane perpendicular to the optical axis and different from the first imaginary plane.

19. A light-emitting device according to any one of claims 1 to 18, wherein the virtual lattice is a virtual square lattice, the lattice spacing of the virtual square lattice and the emission wavelength λ of the light-emitting portion satisfy the condition for M-point oscillation, four in-plane wave vectors each including a wave number spread corresponding to the angular spread of the output light from the light-emitting device are formed in the 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.

Images