Surface light-emitting element

Abstract

[Problem] To provide a surface light-emitting element capable of improving light-emitting efficiency by suppressing thermal interference. [Solution] This surface light-emitting element includes a substrate, a plurality of light-emitting elements arranged separately in a plane on the substrate, and a low-heat conduction part arranged between two adjacent light-emitting elements in the plane and having a lower thermal conductivity than the substrate. Each of the plurality of light-emitting elements has a first reflection member and a second reflection member constituting a resonator, and the second reflection member has a concave surface for condensing light in the direction of the first reflection member.

Description

Surface-emitting element

[0001] The present disclosure relates to a surface-emitting device.

[0002] A VCSEL (Vertical Cavity Surface Emitting Laser), which has multiple light-emitting elements arranged on a substrate, has been attracting attention. Patent Document 1 discloses a configuration in which one of two reflecting mirrors arranged at both ends of a resonator is a concave mirror in order to reduce diffraction loss due to lateral optical field confinement.

[0003] International Publication No. 2018 / 083877

[0004] In a VCSEL, the volume of the active layer of each light-emitting element is very small, so the temperature in the vicinity of the active layer of the light-emitting element becomes high during light emission.

[0005] In order to increase the light output of a VCSEL, it is necessary to narrow the pitch between adjacent light-emitting elements and increase the number of light-emitting elements. However, increasing the number of light-emitting elements may result in a decrease in light-emitting efficiency due to thermal interference between the light-emitting elements (also known as thermal crosstalk).

[0006] For example, in the light-emitting element disclosed in Patent Document 1, the thermal conductivity of each layer inside the resonator is isotropic, and heat generated by the light-emitting element during light emission spreads in the in-plane direction of the substrate, making it prone to thermal interference with other light-emitting elements.

[0007] Therefore, the present disclosure provides a surface light emitting device that can suppress thermal interference and improve light emitting efficiency.

[0008] In order to solve the above problems, according to the present disclosure, there is provided a surface light emitting device comprising: a substrate; a plurality of light emitting elements arranged at a distance within a plane on the substrate; and low thermal conductivity portions each arranged between two adjacent light emitting elements within the plane and having a thermal conductivity lower than that of the substrate, wherein each of the plurality of light emitting elements has a first reflecting member and a second reflecting member that form a resonator, and the second reflecting member has a concave surface that focuses light in the direction of the first reflecting member.

[0009] The low thermal conductivity portion may be disposed between two of the first reflecting members adjacent to each other in a plane.

[0010] The two first reflecting members adjacent to each other in a plane and the low thermal conductivity portion disposed therebetween may be disposed along one direction of the substrate in a plan view.

[0011] The low thermal conductive portion may be an anisotropic thermal conductive portion having different thermal conductivities in an in-plane direction and in a stacking direction of the substrate.

[0012] The anisotropic heat conduction portion may have a thermal conductivity in an in-plane direction that is smaller than the thermal conductivity in the stacking direction.

[0013] The distance in a planar view between the low thermal conductivity portion and the first reflecting member located closest to the low thermal conductivity portion may be equal to or greater than the resonator length of the light-emitting element and equal to or less than half the pitch between two adjacent light-emitting elements.

[0014] The volume of the low thermal conductivity portion may be half or less of the volume of a resonator medium disposed between the first reflecting member and the second reflecting member.

[0015] The low thermal conductivity portion may be made of metal, glass, resin, ceramic, or oxide.

[0016] The low thermal conductivity portion may be a recess in contact with air, or a hollow member the inside of which is filled with air or evacuated.

[0017] A plurality of the low thermal conductive portions having the same thermal conductivity may be arranged between two adjacent light emitting elements in at least one of a surface direction and a stacking direction.

[0018] A plurality of the low thermal conductive portions each having a different thermal conductivity may be arranged between two adjacent light emitting elements in at least one of a surface direction and a stacking direction.

[0019] The low thermal conductivity portion may include a reflective film disposed on a side surface thereof.

[0020] A part of the light resonated between the first reflecting member and the second reflecting member may be reflected by the reflecting film, and light having a uniform polarization state due to the light reflected by the reflecting film may be emitted.

[0021] The heat exchanger may further include a first electrode disposed on the low thermal conductivity portion, wherein a surface of the low thermal conductivity portion that comes into contact with the first electrode is flat.

[0022] The light-emitting element may include a plurality of second electrodes spaced apart in a first direction, each extending in a second direction intersecting the first direction, and a plurality of the first electrodes spaced apart in the second direction, each extending in the first direction, and the plurality of light-emitting elements may be arranged at points where the plurality of first electrodes and the plurality of second electrodes intersect.

[0023] The first reflecting members of the light-emitting elements may be spaced apart from one another within a plane, and the second reflecting members of the light-emitting elements may be integrally connected within the plane.

[0024] Each of the plurality of first reflecting members of the plurality of light-emitting elements may be arranged spaced apart in a plane, and each of the plurality of second reflecting members of the plurality of light-emitting elements may be arranged spaced apart in a plane.

[0025] Each of the plurality of light emitting elements may be driven individually.

[0026] By controlling at least one of the material and the shape of the low thermal conductivity portion, the direction and magnitude of the stress applied to the corresponding light emitting element may be changed, thereby controlling the polarization state.

[0027] The low thermal conductivity portion may be arranged to surround the corresponding light-emitting element, and the direction and magnitude of the stress applied to the corresponding light-emitting element may be changed by controlling the distance from the corresponding light-emitting element depending on the direction.

[0028] 1 is a cross-sectional view of a surface light-emitting device according to a first embodiment of the present disclosure. FIG. 2 is a diagram schematically showing the propagation direction of heat generated in a light-emitting device. FIG. 3 is a cross-sectional view of a surface light-emitting device according to a modified example of the first embodiment. FIG. 4 is a diagram showing the correspondence relationship between the current flowing in an active layer in a surface light-emitting device and the optical output. FIG. 5 is a diagram showing the position of each light-emitting device in a surface light-emitting device with dots. FIG. 6 is a diagram showing a curve of the amount of thermal crosstalk. FIG. 7 is a cross-sectional view of a surface light-emitting device in which a second reflecting member has a flat surface. FIG. 8 is a cross-sectional view of a surface light-emitting member in which a concave surface is formed. FIG. 9 is a cross-sectional view of a surface light-emitting device in which a concave surface is formed. FIG. 10 is a cross-sectional view of a surface light-emitting device according to a modified example of the seventh embodiment. 18A to 18E are typical plan views of low thermal conductivity parts included in the surface light emitting devices according to the first to seventh embodiments. A diagram showing an example of stress applied to a light emitting device. A cross-sectional view of a surface light emitting device according to the ninth embodiment. A block diagram showing an example of the configuration of a distance measuring system. An explanatory diagram of the STL method. An explanatory diagram of the distance measuring principle of the STL method. A block diagram showing an example of the general configuration of a vehicle control system. An explanatory diagram showing an example of the installation positions of an outside vehicle information detection unit and an imaging unit.

[0029] Hereinafter, an embodiment of a surface light emitting device will be described with reference to the drawings. The following description will focus on the main components of the surface light emitting device, but the surface light emitting device may have components or functions that are not shown or described. The following description does not exclude components or functions that are not shown or described.

[0030] 1 is a cross-sectional view of a surface light emitting device 1 according to a first embodiment of the present disclosure. As shown in FIG. 1, the surface light emitting device 1 according to the first embodiment includes a substrate 2, a plurality of light emitting elements 3, and a plurality of low thermal conductive portions 4.

[0031] The substrate 2 is, for example, an n-type GaN substrate, but the specific material of the substrate 2 is not limited.

[0032] The plurality of light emitting elements 3 are arranged at intervals within the plane of the substrate 2. The surface light emitting element 1 according to the first embodiment is called a VCSEL.

[0033] The low thermal conductive portions 4 are disposed between two adjacent light emitting elements 3 within the plane of the substrate 2. The low thermal conductive portions 4 have a lower thermal conductivity than the substrate 2. The material of the low thermal conductive portions 4 is, for example, metal, glass, resin, ceramic, or oxide.

[0034] Each of the light-emitting elements 3 has a first reflecting member 5 and a second reflecting member 6 that form a resonator. The first reflecting member 5 is disposed on the light-emitting surface S1 side. The second reflecting member 6 is disposed on the surface S2 side opposite the light-emitting surface S1.

[0035] The first reflecting member 5 and the second reflecting member 6 are reflecting layers made of the same or different dielectric materials or semiconductor materials. As a specific example, the first reflecting member 5 and the second reflecting member 6 are made of SiO ２ / Ta ２ O ５ It is a dielectric multilayer film consisting of

[0036] A first reflecting member 5 is disposed for each of the plurality of light-emitting elements 3. The plurality of first reflecting members 5 are disposed spaced apart from one another on the light emission surface S1. A low thermal conductivity portion 4 is disposed between two adjacent first reflecting members 5 within the plane. More specifically, the two adjacent first reflecting members 5 within the plane and the low thermal conductivity portion 4 disposed therebetween are disposed along one direction of the substrate 2 when viewed in a plan view.

[0037] A second reflecting member 6 is disposed for each of the plurality of light-emitting elements 3. The second reflecting member 6 has a concave surface 6a that focuses light in the direction of the first reflecting member 5. The plurality of second reflecting members 6 are connected to each other to form a reflecting layer 7.

[0038] Although not shown in FIG. 1 , a lower cladding layer is disposed on the substrate 2. A lower cladding layer is disposed on the lower contact layer. An active layer 8 is disposed on the lower cladding layer. A region 9 into which impurity ions are implanted is provided around the active layer 8, thereby forming a current confinement structure. An upper cladding layer is disposed on the active layer 8. An upper contact layer 10 is disposed on the upper cladding layer. The upper contact layer 10 is formed of, for example, ITO (Indium Tin Oxide). A p-electrode 11 is disposed on the upper contact layer 10. Furthermore, an n-electrode 12 is disposed on the lower contact layer.

[0039] In this specification, the lower cladding layer, the lower contact layer, the active layer 8, and the upper cladding layer may be collectively referred to as the substrate 2. The low thermal conductivity portion 4 according to the first embodiment is disposed between two adjacent light emitting elements 3 in the plane of the substrate 2 so as to be embedded in a part of the substrate 2.

[0040] The low thermal conductivity portion 4 is arranged so as to penetrate, for example, the upper contact layer 10, the upper cladding layer, the active layer 8, the lower cladding layer, and the lower contact layer.

[0041] 2 is a diagram schematically showing the propagation direction of heat generated in the light-emitting element 3. Heat generated in the active layer 8 of the light-emitting element 3 propagates in the planar direction as indicated by arrow y1 in FIG. 2 and also propagates in the stacking direction as indicated by arrow y2. The low thermal conductivity portion 4 reduces the amount of heat transferred from the active layer 8 in the planar direction, thereby suppressing the diffusion of heat propagating in the planar direction.

[0042] The effect of suppressing heat generation from the light emitting element 3 varies depending on the length in the stacking direction of the low thermal conductive portion 4. The longer the length in the stacking direction of the low thermal conductive portion 4, the more effectively the heat generation can be suppressed.

[0043] Fig. 3 is a cross-sectional view of a surface light emitting device 1 according to a modified example of the first embodiment. In the surface light emitting device 1 according to the modified example, as shown in Fig. 3, a low thermal conductivity portion 4 is arranged so as to penetrate the substrate 2. In the surface light emitting device 1 according to the modified example shown in Fig. 3, the volume of the low thermal conductivity portion 4 is larger than that of the surface light emitting device 1 shown in Fig. 1, and therefore, the propagation of heat in the surface direction of the light emitting device 3 can be further suppressed.

[0044] In the surface-emitting device 1, the greater the heat generation amount of each light-emitting element 3, the greater the thermal resistance of the current flowing in the active layer 8, resulting in a decrease in light-emitting efficiency. Fig. 4 is a diagram showing the correspondence relationship between the current flowing in the active layer 8 and the light output in the surface-emitting device 1. The curve w1 in Fig. 4 shows the characteristics of the surface-emitting device 1 at high temperature and high thermal resistance due to the heat generation of the light-emitting element 3, and the curve w2 shows the characteristics of the surface-emitting device 1 at low temperature and low thermal resistance. As can be seen from the curves w1 and w2, the higher the temperature and thermal resistance, the more the light output is suppressed even when a current is passed through the active layer 8, and the worse the heat-generating efficiency becomes.

[0045] 5A and 5B are diagrams illustrating a method for calculating thermal resistance. Fig. 5A is a diagram in which the position of each light-emitting element 3 in a surface light-emitting element 1 is represented by a dot. The amount of thermal crosstalk α(d) that a light-emitting element 3 receives from another light-emitting element 3 is expressed as a function of the linear distance d between the light-emitting element 3 and the other light-emitting element 3. Specifically, the amount of thermal crosstalk α(d) is expressed by the following equation (1):

[0046] α(d)=ΔT / ΔTj (1) ΔT in equation (1) represents the temperature change at the light-emitting center point of a certain light-emitting element 3. ΔTj represents the temperature change of another light-emitting element 3 located at a distance d from the certain light-emitting element 3.

[0047] 5B is a diagram showing a curve w3 of the amount of thermal crosstalk α(d). The horizontal axis of FIG. 5B represents the distance d, and the vertical axis represents the amount of thermal crosstalk α(d). As shown by the curve w3, the amount of thermal crosstalk increases exponentially as the distance d decreases.

[0048] The thermal resistance Rth_array of a certain light-emitting element 3 is expressed by the following formula (2).

[0049]

[0050] In equation (2), Rth_single is the thermal resistance when there is no thermal crosstalk. As shown in equation (2), the greater the amount of thermal crosstalk, the greater the thermal resistance, and the greater the decrease in light output, as shown by curves w1 and w2 in Figure 4. Therefore, it is important to suppress the amount of thermal crosstalk.

[0051] In the surface light emitting element 1 according to the first embodiment, a low thermal conductivity portion 4 is disposed between two adjacent light emitting elements 3 in the plane. By providing the low thermal conductivity portion 4, the amount of thermal crosstalk can be reduced.

[0052] As described above, the low thermal conductivity portion 4 is embedded in the substrate 2. Embedding the low thermal conductivity portion 4 in the substrate 2 may apply stress to the substrate 2, which may unintentionally reduce the light-emitting characteristics. For example, embedding the low thermal conductivity portion 4 in the substrate 2 may cause the substrate 2 to warp. If the substrate 2 warps, the internal loss of the resonator formed by the first reflecting member 5 and the second reflecting member 6 increases, and the threshold current and slope efficiency at which resonated light begins to be output to the outside may decrease.

[0053] In particular, when the second reflecting member 6 has a flat surface as in Fig. 6A, the light-emitting characteristics are likely to deteriorate due to warpage of the substrate 2. In contrast, the second reflecting member 6 in the surface-emitting device 1 according to the first embodiment has a concave surface 6a as shown in Fig. 6B, and light incident on the second reflecting member 6 from the active layer 8 is reflected and condensed by the concave surface 6a before being incident on the first reflecting member 5. Even if the substrate 2 of the surface-emitting device 1 according to the first embodiment is warped, light is condensed by the concave surface 6a of the second reflecting member 6, so that deterioration of the light-emitting characteristics is suppressed more than in the surface-emitting device 1 of Fig. 6A.

[0054] Fig. 7 is a diagram showing the correspondence relationship between resonator length and thermal resistance. The horizontal axis of Fig. 7 represents resonator length [µm], and the vertical axis represents the relative value of thermal resistance. The longer the resonator length of a resonator composed of a first reflecting member 5 and a second reflecting member 6, the smaller the thermal resistance and the higher the optical output. The resonator length when the second reflecting member 6 is flat as in Fig. 6A is within the dashed line range br1 in Fig. 7, and the resonator length when the second reflecting member 6 has a concave surface 6a as in Fig. 6B is within the dashed line range br2 in Fig. 7.

[0055] As shown in FIG. 7, by forming the second reflecting member 6 into a concave surface 6a, the cavity length can be increased, the thermal resistance can be reduced, and the optical output can be increased.

[0056] The distance in a plan view between the low thermal conductivity portion 4 and the first reflecting member 5 located closest to the low thermal conductivity portion 4 is equal to or greater than the cavity length of the light-emitting element 3 and equal to or less than half the pitch between two adjacent light-emitting elements 3. The cavity length is, for example, 10 μm or greater. The volume of the low thermal conductivity portion is equal to or less than half the volume of the cavity medium disposed between the first reflecting member and the second reflecting member.

[0057] In this way, in the first embodiment, the low thermal conductivity portion 4 is provided between two adjacent light emitting elements 3 in the plane of the substrate 2, which reduces the amount of heat transferred from each light emitting element 3 to diffuse in the in-plane direction, thereby suppressing the amount of thermal crosstalk between the plurality of light emitting elements 3. Therefore, by providing the low thermal conductivity portion 4, it is possible to suppress a decrease in the light emitting efficiency of each light emitting element 3 and increase the light output.

[0058] Second Embodiment A surface light emitting device 1 according to a second embodiment has the same cross-sectional structure as that shown in Fig. 1. However, the surface light emitting device 1 according to the second embodiment is characterized in that a low thermal conductivity part 4 is disposed in the vicinity of an opening through which light is emitted. The opening is provided in a position that overlaps with a first reflecting member 5 and a second reflecting member 6 when viewed in a planar state.

[0059] 8 is a plan view of the periphery of the opening 13 as viewed from the light emitting surface S1 side, and a diagram showing the emission modes of light emitted from the surface light emitting device 1. As shown in the plan view of FIG. 8, the low thermal conductivity portion 4 is arranged along the outer periphery of the approximately circular opening 13 so as to surround the opening 13. Near the center of the opening 13, light is mainly emitted in the fundamental mode, which emits light at the original emission wavelength, but the further away from the center of the opening 13, the higher-order mode, which emits light at a harmonic wavelength of the original emission wavelength, becomes more intense. By arranging the low thermal conductivity portion 4 close to the outer periphery of the opening 13, the internal loss of the resonator for the higher-order mode can be increased, and transverse mode control of the emitted light can be performed.

[0060] The low thermal conductive portion 4 is preferably disposed within 100 μm of the opening 13. More preferably, the low thermal conductive portion 4 is disposed within 50 μm of the opening 13. Even more preferably, the low thermal conductive portion 4 is disposed within 20 μm of the opening 13.

[0061] In this way, by arranging the low thermal conductivity portion 4 along the outer periphery of the opening 13 or in the vicinity thereof, the emission intensity in the higher order mode can be suppressed and the emission wavelength can be made uniform.

[0062] Third Embodiment In the first and second embodiments, an example was described in which a low thermal conductive portion 4 having a thermal conductivity lower than that of the substrate 2 was provided, but the thermal conductivity of the low thermal conductive portion 4 may differ depending on the direction. Hereinafter, a member having different thermal conductivities in the in-plane direction and the stacking direction of the substrate 2 is referred to as an anisotropic thermal conductive portion.

[0063] Fig. 9 is a cross-sectional view of a surface light emitting device 1a according to the third embodiment. The surface light emitting device 1a according to the third embodiment shown in Fig. 9 differs from that shown in Fig. 1 only in that the low thermal conductivity portion 4 is replaced with an anisotropic thermal conductivity portion 4a.

[0064] Fig. 10 is a diagram showing the thermal conductivity of the anisotropic thermal conductive portion 4a, where the horizontal axis represents the thermal conductivity in the in-plane direction and the vertical axis represents the thermal conductivity in the stacking direction of the substrate 2. Fig. 10 shows an example in which the thermal conductivity in the stacking direction is greater than the in-plane direction. As shown in Fig. 10, by providing an anisotropic thermal conductive portion 4a with a smaller thermal conductivity in the in-plane direction, the amount of thermal crosstalk between multiple light-emitting elements 3 can be further suppressed.

[0065] The thermal conductivity of the low thermal conductive portion 4 (anisotropic thermal conductive portion 4a) in the in-plane direction is preferably 20 W / m·K or less, and more preferably 10 W / m·K or less.

[0066] The anisotropic ratio (thermal conductivity in the in-plane direction: thermal conductivity in the stacking direction) of the anisotropic heat conductive portion 4a is preferably 1: 2 or more. The direction in which the thermal conductivity of the anisotropic heat conductive portion 4a is highest may be a direction inclined from the stacking direction (for example, a direction within 30 degrees).

[0067] (Fourth Embodiment) FIG. 11 is a cross-sectional view of a surface-emitting device 1b according to a fourth embodiment. In the surface-emitting device 1b according to the fourth embodiment shown in FIG. 11, at least one of the types and the number of low thermal conductive portions 4 arranged between two adjacent light-emitting elements 3 varies depending on the location of the light-emitting elements 3 arranged in the plane. FIG. 11 illustrates an example in which, between two adjacent light-emitting elements 3, there are provided a location where multiple low thermal conductive portions 4, 4a of different types are stacked, a location where multiple low thermal conductive portions 4 of the same type are arranged in the plane direction, and a location where multiple low thermal conductive portions 4, 4a of different types are arranged in the plane direction. However, this example is merely one example, and various variations in the arrangement of the low thermal conductive portions 4 are possible. When multiple low thermal conductive portions 4 of different types are arranged, low thermal conductive portions 4 having the same thermal conductivity in the plane direction and the stacking direction may be arranged, or low thermal conductive portions 4 having different thermal conductivity in the plane direction and the stacking direction may be arranged.

[0068] As described above, in the fourth embodiment, since the degree of heat generation of the surface light-emitting element 1 may vary depending on the location, the degree of heat generation in the in-plane direction can be made uniform by changing the type and number of low thermal conductivity sections 4 placed between two adjacent light-emitting elements 3 depending on the location.

[0069] 12 is a cross-sectional view of a surface light emitting device 1c according to a fifth embodiment. The surface light emitting device 1c according to the fifth embodiment shown in Fig. 12 differs from the surface light emitting device 1 shown in Fig. 1 in that it includes a reflective film 4b on the side surface of the low thermal conductivity portion 4.

[0070] A portion of the light resonated in the resonator of the light-emitting element 3 becomes leaked light and travels toward the low thermal conductivity portion 4. By reflecting the leaked light by the reflective film 4b, the polarization state of the light resonated in the resonator can be aligned. In other words, the reflective film 4b functions as a polarization control member. The reflective film 4b is formed of, for example, a single-layer film or a multi-layer film containing a metal material or a dielectric material.

[0071] In this way, with a simple configuration in which the reflective film 4 b is simply disposed on the side surface of the low thermal conductive portion 4 , the polarization state of the light emitted from each light emitting element 3 can be aligned.

[0072] Sixth Embodiment Fig. 13 is a cross-sectional view of a surface light emitting device 1d according to a sixth embodiment. In the surface light emitting device 1d according to the sixth embodiment shown in Fig. 13, the upper surface of the low thermal conductivity portion 4 is flattened, and a pad (electrode) 14 is disposed thereon. The pad 14 is used to pass current through the active layer 8 of each light emitting element 3, and is connected flush with the p-electrode 11 disposed around the area where the plurality of light emitting elements 3 are disposed. This prevents a step from being formed between the pad 14 and the p-electrode 11, making it less likely for electromigration to occur, thereby improving the reliability of the surface light emitting element 1.

[0073] 14 is a cross-sectional view of a surface light emitting device 100 according to a comparative example. If the top surface of the low thermal conductivity portion 4 is not flattened, unevenness is formed on the top surface, and when a pad 14 is placed on top of it, a step is formed between the pad 14 and the p-electrode 11. If there is a step, the metal material such as aluminum (Al) that is the material of the p-electrode 11 will move, increasing the contact resistance between the p-electrode 11 and the pad 14 and making it more likely to cause defects such as disconnection.

[0074] In this way, in the sixth embodiment, the upper surface of the low thermal conductivity portion 4 is flattened and the pad 14 is placed thereon, so that no step is formed between the pad 14 and the p-electrode 11, thereby improving the reliability of the surface-emitting element 1.

[0075] 15 is a cross-sectional view of a surface light emitting device 1e according to a seventh embodiment. In the surface light emitting device 1e according to the seventh embodiment shown in Fig. 15, a p-electrode 11 to which a voltage can be applied is disposed on each low thermal conductivity portion 4, and a second reflecting member 6 disposed on the surface opposite to the light emitting surface S1 is integrally formed and connected to an n-electrode 12.

[0076] This allows the n-electrodes 12 of all the light-emitting elements 3 to be set to the same potential, and by individually controlling the p-electrodes 11, the light emission of each light-emitting element 3 can be individually controlled.

[0077] Fig. 16 is a schematic plan view of a surface light emitting device 1e according to the seventh embodiment. As shown in Fig. 16, the surface light emitting device 1e according to the seventh embodiment includes, for example, a plurality of p-electrodes 11 arranged spaced apart in the second direction Y and each extending in the first direction X, a plurality of n-electrodes 12 arranged spaced apart in the first direction X and each extending in the second direction Y, and a plurality of light emitting elements 3 arranged at points where these p-electrodes 11 and n-electrodes 12 intersect. The cross-sectional structure along line A-A in Fig. 16 is shown in Fig. 15.

[0078] In this way, by arranging the plurality of strip-shaped p-electrodes 11 and n-electrodes 12 in the first direction X and the second direction Y, each light-emitting element 3 can be driven individually.

[0079] At least one of the p-electrode 11 and the n-electrode 12 may not be in a strip shape, but may be separated for each light-emitting element 3 .

[0080] 17 is a cross-sectional view of a surface light emitting device 1f according to a modified example of the seventh embodiment. In the surface light emitting device 1f according to the modified example shown in FIG. 17, the second reflecting members 6 are disposed separately for each light emitting element 3, and n-electrodes 12 are disposed between adjacent second reflecting members 6. This allows not only the p-electrodes 11 but also the n-electrodes 12 to be driven individually.

[0081] Eighth Embodiment The low thermal conductivity portion 4 included in the surface-emitting devices 1 to 1f according to the first to seventh embodiments is disposed between two adjacent light-emitting elements 3 so as to penetrate the upper contact layer 10, the upper cladding layer, the active layer 8, the lower cladding layer, and the lower contact layer. Therefore, depending on the material of the low thermal conductivity portion 4, stress is applied to the upper contact layer 10, the upper cladding layer, the active layer 8, the lower cladding layer, and the lower contact layer. By controlling at least one of the material and the shape of the low thermal conductivity portion 4, the direction and magnitude of the stress applied to the corresponding light-emitting element 3 can be changed, thereby controlling the polarization state.

[0082] FIG. 18 is a representative plan view of the low thermal conductivity portion 4 included in the surface light emitting devices 1 to 1f according to the first to seventh embodiments. As shown in FIGS. 18A to 18E, there are multiple options for the planar shape of the low thermal conductivity portion 4. The low thermal conductivity portion 4 in FIG. 18A is circular and is arranged so as to isotropically surround the periphery of the light emitting element 3. The low thermal conductivity portion 4 in FIG. 18B has a structure in which a portion of the circular shape is missing. The low thermal conductivity portion 4 in FIG. 18C has an elliptical shape, and the distance from the light emitting element 3 varies depending on the direction. The low thermal conductivity portion 4 in FIG. 18D has a rectangular shape, and the distance from the light emitting element 3 varies depending on the direction. The low thermal conductivity portion 4 in FIG. 18E is circular but is made of multiple materials.

[0083] 18A shows that the stress is uniform in the in-plane direction, whereas in Figures 18B to 18E the stress is non-uniform in the in-plane direction. The direction and magnitude of the stress applied to the light-emitting element 3 change depending on the distance from the light-emitting element 3 to the low thermal conductivity portion 4. Therefore, by controlling the shape and size of the low thermal conductivity portion 4, it is possible to adjust the direction and magnitude of the stress applied to the light-emitting element 3, and thereby to arbitrarily control the polarization state of the light emitted from each light-emitting element 3.

[0084] Fig. 19 is a diagram showing an example of stress applied to the light-emitting element 3. Fig. 19A shows an example in which compressive stress is applied to the light-emitting element 3 from four directions that are perpendicular to each other. Fig. 19B shows an example in which compressive stress is applied to the light-emitting element 3 from directions that face each other, and tensile stress is applied from two directions that are 90 degrees different from the compressive stress directions. The polarization state of the light-emitting element 3 can be made different between Fig. 19A and Fig. 19B.

[0085] Thus, in the eighth embodiment, by controlling at least one of the material and shape of the low thermal conductivity portion 4, the direction and magnitude of the stress applied to the light-emitting element 3 can be controlled, thereby controlling the polarization state of the light emitted from the light-emitting element 3.

[0086] Ninth Embodiment Fig. 20 is a cross-sectional view of a surface light emitting device 1g according to a ninth embodiment. The surface light emitting device 1g according to the ninth embodiment is different from the surface light emitting device 1 of Fig. 1 in that the material of the low thermal conductivity portion 4 is different. The low thermal conductivity portion 4 according to the ninth embodiment shown in Fig. 20 may be a recess in contact with air, or a hollow member 4c the inside of which is filled with air or evacuated. The hollow member 4c may have a structure in which a large number of voids are included in the base material of the low thermal conductivity portion 4.

[0087] The low thermal conductive portion 4 according to the ninth embodiment can also be applied to the low thermal conductive portions 4 according to the first to eighth embodiments.

[0088] (Configuration of Distance Measuring System 40) FIG. 21 is a block diagram showing a configuration example of a distance measuring system 40 as an example of implementation of the laser device 1 according to this embodiment.

[0089] As shown in the figure, the distance measurement system 40 includes a light emitting unit 41, a driving unit 42, a power supply circuit 43, a light emitting side optical system 44, a light receiving side optical system 45, a light receiving unit 46, a signal processing unit 47, a control unit 48, and a temperature detection unit 49.

[0090] The light-emitting unit 41 emits light from a plurality of light sources. The light-emitting unit 41 and the light-emitting side optical system 44 correspond to the laser element 1 described above. The light-emitting unit 41 can be configured using any of the laser elements 1, 1a, 1b, and 1c according to the first to seventh embodiments (hereinafter collectively referred to as the laser element 1). The light-emitting unit 41 may also be, for example, a VECSEL (Vertical External Cavity Surface Emitting Laser) in which a plurality of laser elements 1 are arranged in a one-dimensional or two-dimensional direction.

[0091] The drive unit 42 is configured to have a power supply circuit 43 for driving the light emitting unit 41. The power supply circuit 43 generates a power supply voltage (a drive voltage Vd described later) for the drive unit 42 based on an input voltage (an input voltage Vin described later) from, for example, a battery (not shown) or the like provided in the distance measuring system 40. The drive unit 42 drives the light emitting unit 41 based on the power supply voltage.

[0092] Light emitted from the light-emitting unit 41 is irradiated onto a subject (object) S, which is the target of distance measurement, via a light-emitting side optical system 44. The light thus irradiated is reflected from the subject S and enters the light-receiving surface of a light-receiving unit 46 via a light-receiving side optical system 45.

[0093] The light receiving unit 46 has a light receiving element such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor, receives reflected light from the subject S that enters via the light receiving side optical system 45 as described above, converts the light into an electrical signal, and outputs the electrical signal. The light receiving unit 46 and the light receiving side optical system 45 constitute a light receiving device.

[0094] The light receiving unit 46 performs processes such as CDS (Correlated Double Sampling) and AGC (Automatic Gain Control) on the electrical signal obtained by photoelectrically converting the received light, and then performs A / D (Analog / Digital) conversion on the electrical signal, and outputs the resulting digital data to the signal processing unit 47 at the subsequent stage.

[0095] Furthermore, the light receiving unit 46 in this example outputs a frame synchronization signal Fs to the driving unit 42. This enables the driving unit 42 to cause the light emitting element 23 in the light emitting unit 41 to emit light at a timing according to the frame period of the light receiving unit 46.

[0096] The signal processing unit 47 has a signal processor such as a DSP (Digital Signal Processor), etc. The signal processing unit 47 performs various signal processes on the digital signal input from the light receiving unit 46.

[0097] The control unit 48 has, for example, a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., or an information processing device such as a DSP, and controls the drive unit 42 for controlling the light-emitting operation by the light-emitting unit 41, and controls the light-receiving operation by the light-receiving unit 46.

[0098] The control unit 48 functions as a distance measuring unit 28a. The distance measuring unit 28a measures the distance to the subject S based on a signal input via the signal processing unit 47 (i.e., a signal obtained by receiving reflected light from the subject S). The distance measuring unit 28a in this example measures the distance to each part of the subject S in order to be able to identify the three-dimensional shape of the subject S.

[0099] The specific distance measurement method used in the distance measurement system 40 will be described later.

[0100] The temperature detection unit 49 detects the temperature of the light emitting unit 41. The temperature detection unit 49 performs temperature detection using, for example, a diode.

[0101] In this example, information about the temperature detected by the temperature detection unit 49 is supplied to the drive unit 42, which enables the drive unit 42 to drive the light emitting unit 41 based on the temperature information.

[0102] (Range Measurement Method) The distance measurement method used in the distance measurement system 40 may be, for example, a STL (Structured Light) method or a ToF (Time of Flight) method.

[0103] The STL method is a method for measuring distance based on an image of a subject S illuminated with light having a predetermined light / dark pattern, such as a dot pattern or a grid pattern.

[0104] Fig. 22A is an explanatory diagram of the STL method. In the STL method, pattern light Lp having a dot pattern such as that shown in Fig. 22A is irradiated onto a subject S. The pattern light Lp is divided into a plurality of blocks BL, and a different dot pattern is assigned to each block BL (dot patterns are arranged not to overlap between blocks BL).

[0105] FIG. 22B is an explanatory diagram of the distance measurement principle of the STL system.

[0106] In this example, a wall W and a box BX placed in front of it are treated as the subject S, and pattern light Lp is irradiated onto the subject S. "G" in the drawing schematically represents the angle of view of the light receiving unit 46.

[0107] In addition, "BLn" in the drawing denotes the light of a certain block BL in the pattern light Lp, and "dn" denotes the dot pattern of the block BLn projected on the light-receiving image by the light-receiving unit 46.

[0108] Here, if there is no box BX in front of the wall W, the dot pattern of the block BLn is projected at the position "dn'" in the figure in the received light image. In other words, the position at which the pattern of the block BLn is projected in the received light image differs depending on whether the box BX is present or not, and specifically, the pattern is distorted.

[0109] The STL method is a method for determining the shape and depth of the subject S by utilizing the fact that the irradiated pattern is distorted by the object shape of the subject S. Specifically, it is a method for determining the shape and depth of the subject S from the way the pattern is distorted.

[0110] When the STL system is employed, for example, a global shutter type IR (Infrared) light receiving unit 46 is used as the light receiving unit 46. In the case of the STL system, the distance measuring unit 28a controls the drive unit 42 so that the light emitting unit 41 emits pattern light, detects distortion of the pattern in the image signal obtained via the signal processing unit 47, and calculates the distance based on the distortion of the pattern.

[0111] Next, the ToF method is a method for measuring the distance to an object by detecting the time of flight (time difference) of light emitted from the light-emitting unit 41, reflected by the object, and reaching the light-receiving unit 46.

[0112] When the so-called direct ToF (dToF) method is adopted as the ToF method, a SPAD (Single Photon Avalanche Diode) is used as the light receiving unit 46, and the light emitting unit 41 is pulse-driven. In this case, the distance measuring unit 28a calculates the time difference between light emission and reception of light emitted from the light emitting unit 41 and received by the light receiving unit 46, based on a signal input via the signal processing unit 47, and calculates the distance to each part of the subject S based on the time difference and the speed of light.

[0113] When the so-called indirect ToF (iToF) method (phase difference method) is adopted as the ToF method, the light receiving unit 46 used is, for example, a light receiving unit 46 capable of receiving IR.

[0114] <Application to a Mobile Body> The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of mobile body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, or a robot.

[0115] FIG. 23 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0116] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 23, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also shown as functional components of the integrated control unit 12050 are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (Interface) 12053.

[0117] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0118] The body system control unit 12020 controls the operation of various devices equipped in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0119] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc. based on the received images.

[0120] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0121] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0122] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the distance between vehicles, maintaining vehicle speed, vehicle collision warning, vehicle lane departure warning, etc.

[0123] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0124] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching from high beams to low beams.

[0125] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying information to vehicle occupants or the outside of the vehicle. In the example of Fig. 23, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0126] FIG. 24 is a diagram showing an example of the installation position of the imaging unit 12031.

[0127] In FIG. 24, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0128] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 provided on the top of the windshield inside the vehicle cabin is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0129] 24 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0130] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for phase difference detection.

[0131] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation.

[0132] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines a collision risk that indicates the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0133] At least one of the image capturing units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching on a series of feature points that indicate the outline of an object to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0134] The above describes an example of a vehicle control system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to the vehicle exterior information detection unit 12030 and the like among the above-described configurations. By applying any of the laser elements 1, 1a, 1b, and 1c according to the first to seventh embodiments to the light-emitting elements of the vehicle exterior information detection unit 12030 and the like, it is possible to accurately measure the distance to an obstacle or the like located around the vehicle.

[0135] The present technology may have the following configurations: (1) A surface light-emitting device comprising: a substrate; a plurality of light-emitting elements arranged at a distance in a plane on the substrate; and low thermal conductivity portions arranged between two adjacent light-emitting elements in the plane and having a thermal conductivity lower than that of the substrate, wherein each of the plurality of light-emitting elements has a first reflecting member and a second reflecting member that form a resonator, and the second reflecting member has a concave surface that focuses light in the direction of the first reflecting member. (2) The surface light-emitting device according to (1), wherein the low thermal conductivity portion is arranged between two adjacent first reflecting members in the plane. (3) The surface light-emitting device according to (2), wherein the two adjacent first reflecting members in the plane and the low thermal conductivity portion arranged therebetween are arranged along one direction of the substrate in a plan view. (4) The surface light-emitting device according to any one of (1) to (3), wherein the low thermal conductivity portion is an anisotropic thermal conductive portion having different thermal conductivities in an in-plane direction and a stacking direction of the substrate. (5) The surface light-emitting device according to (4), wherein the anisotropic thermal conduction portion has a thermal conductivity in an in-plane direction that is lower than the thermal conductivity in the stacking direction. (6) The surface light-emitting device according to any one of (1) to (5), wherein the distance in a plan view between the low thermal conduction portion and the first reflecting member located closest to the low thermal conduction portion is equal to or greater than the resonator length of the light-emitting element and equal to or less than half the pitch between two adjacent light-emitting elements. (7) The surface light-emitting device according to any one of (1) to (6), wherein the volume of the low thermal conduction portion is equal to or less than half the volume of the resonator medium disposed between the first reflecting member and the second reflecting member. (8) The surface light-emitting device according to any one of (1) to (7), wherein the low thermal conduction portion is metal, glass, resin, ceramic, or oxide. (9) The surface light-emitting device according to any one of (1) to (7), wherein the low thermal conduction portion is a recess in contact with air or a hollow member the interior of which is filled with air or evacuated. (10) A surface light emitting device described in any one of (1) to (9), wherein a plurality of the low thermal conductivity portions having the same thermal conductivity are arranged between two adjacent light emitting elements in at least one of the surface direction and the stacking direction.(11) The surface light emitting device according to any one of (1) to (9), wherein a plurality of the low thermal conductivity sections, each having a different thermal conductivity, are arranged between two adjacent light emitting elements in at least one of the surface direction or the stacking direction. (12) The surface light emitting device according to any one of (1) to (11), comprising a reflective film arranged on a side surface of the low thermal conductivity section. (13) The surface light emitting device according to (12), wherein a portion of light resonating between the first reflecting member and the second reflecting member is reflected by the reflective film, and light having a uniform polarization state is emitted by the light reflected by the reflective film. (14) The surface light emitting device according to any one of (1) to (13), comprising a first electrode arranged on the low thermal conductivity section, and wherein a contact surface of the low thermal conductivity section with the first electrode is flat. (15) The surface light emitting device according to (14), comprising: a plurality of second electrodes arranged at intervals in a first direction and each extending in a second direction intersecting the first direction; and a plurality of the first electrodes arranged at intervals in the second direction and each extending in the first direction, wherein the plurality of light emitting elements are arranged at locations where the plurality of first electrodes intersect with the plurality of second electrodes. (16) The surface light emitting device according to any one of (1) to (15), wherein each of the plurality of first reflecting members included in the plurality of light emitting elements is arranged at intervals in a plane, and the plurality of second reflecting members included in the plurality of light emitting elements is connected integrally in a plane. (17) The surface light emitting device according to any one of (1) to (15), wherein each of the plurality of first reflecting members included in the plurality of light emitting elements is arranged at intervals in a plane, and the plurality of second reflecting members included in the plurality of light emitting elements is arranged at intervals in a plane. (18) The surface light emitting device according to any one of (1) to (17), wherein each of the plurality of light emitting elements is driven individually. (19) The surface light emitting device according to any one of (1) to (18), wherein by controlling at least one of the material and the shape of the low thermal conductivity portion, the direction and magnitude of stress applied to the corresponding light emitting element are changed, thereby controlling the polarization state.(20) The surface light emitting device described in (19), wherein the low thermal conductivity portion is arranged to surround the corresponding light emitting element, and the direction and magnitude of the stress applied to the corresponding light emitting element are changed by controlling the distance from the corresponding light emitting element depending on the direction.

[0136] The aspects of the present disclosure are not limited to the individual embodiments described above, but include various modifications that may be conceived by those skilled in the art, and the effects of the present disclosure are not limited to the above-described contents. In other words, various additions, modifications, and partial deletions are possible within the scope of the conceptual idea and spirit of the present disclosure, which is derived from the contents defined in the claims and their equivalents.

[0137] 1, 1a, 1b, 1c, 1d, 1e, 1f, 1g: surface-emitting element, 2: substrate, 3: light-emitting element, 4: low thermal conductivity portion, 4a: anisotropic thermal conductivity portion, 4b: reflective film, 4c: hollow member, 5: first reflecting member, 6: second reflecting member, 6a: concave surface, 7: reflective layer, 8: active layer, 9: region, 10: upper contact layer, 11: p-electrode, 12: n-electrode, 13: opening, 14: pad, 100: surface-emitting element

Claims

1. A surface-emitting device comprising: a substrate; a plurality of light-emitting elements arranged at intervals within a plane on the substrate; and low thermal conductivity portions each arranged between two adjacent light-emitting elements within the plane and having a thermal conductivity lower than that of the substrate, wherein each of the plurality of light-emitting elements has a first reflecting member and a second reflecting member that form a resonator, and the second reflecting member has a concave surface that focuses light in the direction of the first reflecting member.

2. The surface light emitting device according to claim 1, wherein the low thermal conductivity portion is disposed between two adjacent first reflecting members in the plane.

3. The surface light emitting device according to claim 2, wherein the two adjacent first reflecting members in the plane and the low thermal conductivity portion disposed therebetween are arranged along one direction of the substrate when viewed in a plane.

4. The surface light emitting device according to claim 1, wherein the low thermal conductivity portion is an anisotropic thermal conductivity portion having different thermal conductivities in the in-plane direction and the stacking direction of the substrate.

5. The surface light emitting device according to claim 4, wherein the anisotropic heat conduction portion has a thermal conductivity in an in-plane direction that is smaller than the thermal conductivity in the stacking direction.

6. The surface light emitting element according to claim 1, wherein the distance in a plan view between the low thermal conductivity portion and the first reflecting member located closest to the low thermal conductivity portion is equal to or greater than the cavity length of the light emitting element and equal to or less than half the pitch between two adjacent light emitting elements.

7. The surface light emitting device according to claim 1, wherein the volume of the low thermal conductivity portion is equal to or less than half the volume of the resonator medium disposed between the first reflecting member and the second reflecting member.

8. The surface light emitting device according to claim 1, wherein the low thermal conductivity portion is made of metal, glass, resin, ceramic, or oxide.

9. The surface light emitting device according to claim 1, wherein the low thermal conductivity portion is a recess in contact with air, or a hollow member the interior of which is filled with air or evacuated.

10. The surface light emitting device according to claim 1, wherein a plurality of low thermal conductive portions having the same thermal conductivity are arranged between two adjacent light emitting elements in at least one of the surface direction and the stacking direction.

11. The surface light emitting device according to claim 1, wherein a plurality of low thermal conductive portions each having a different thermal conductivity are arranged between two adjacent light emitting elements in at least one of the surface direction and the stacking direction.

12. The surface light emitting device according to claim 1, further comprising a reflective film disposed on a side surface of the low thermal conductivity portion.

13. The surface-emitting device according to claim 12, wherein a portion of the light resonating between the first reflecting member and the second reflecting member is reflected by the reflecting film, and light having a uniform polarization state is emitted by the light reflected by the reflecting film.

14. The surface light emitting device according to claim 1, further comprising a first electrode disposed on the low thermal conductivity portion, wherein the contact surface of the low thermal conductivity portion with the first electrode is a flat surface.

15. A surface light emitting device as described in claim 14, comprising: a plurality of second electrodes arranged at intervals in a first direction, each extending in a second direction intersecting the first direction; and a plurality of the first electrodes arranged at intervals in the second direction, each extending in the first direction, wherein the plurality of light emitting elements are arranged at locations where the plurality of first electrodes and the plurality of second electrodes intersect.

16. A surface light emitting device according to claim 1, wherein each of the plurality of first reflecting members of the plurality of light emitting elements is arranged spaced apart from one another within a plane, and the plurality of second reflecting members of the plurality of light emitting elements is integrally connected within the plane.

17. A surface light emitting device as described in claim 1, wherein each of the plurality of first reflecting members of the plurality of light emitting elements is arranged spaced apart from each other in a plane, and each of the plurality of second reflecting members of the plurality of light emitting elements is arranged spaced apart from each other in a plane.

18. The surface light emitting device according to claim 1, wherein each of the plurality of light emitting elements is driven individually.

19. The surface light emitting device according to claim 1, wherein the polarization state is controlled by controlling at least one of the material and shape of the low thermal conductivity portion, thereby changing the direction and magnitude of the stress applied to the corresponding light emitting element.

20. A surface light-emitting device as described in claim 19, wherein the low thermal conductivity portion is arranged to surround the corresponding light-emitting element, and the direction and magnitude of the stress applied to the corresponding light-emitting element are changed by controlling the distance from the corresponding light-emitting element depending on the direction.

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