Light-emitting element and distance measuring device

Abstract

[Problem] To provide a light-emitting element and a distance measuring device, which have a vertical cavity surface emitting laser structure and are suitable for long-distance light irradiation. [Solution] The light-emitting element according to the present technology is provided with a plurality of light-emitting portions, a first electrode terminal, and a second electrode terminal. The plurality of light-emitting portions are vertical cavity surface emitting laser elements and are provided with a first electrode and a second electrode, wherein the light-emitting portions that emit light when current flows from the first electrode to the second electrode are arranged one-dimensionally or two-dimensionally in a direction perpendicular to the optical axis of the light emitted from the light-emitting portions. The first electrode terminal is electrically connected to the first electrode. The second electrode terminal is electrically connected to the second electrode. The resistance of the current path from the first electrode terminal through one of the plurality of light-emitting portions to the second electrode terminal is different from the resistance of the current path from the first electrode terminal through another of the plurality of light-emitting portions to the second electrode terminal.

Description

Technical Field

[0001] The present technology relates to a light-emitting element and a distance measuring device, and the light-emitting element has a vertical cavity surface emitting laser structure. Background Art

[0002] The time-of-flight (ToF) method is a distance measuring method. In the ToF method, light is emitted by a light emitter, and the light reflected from a measurement target object is detected by a detector. This makes it possible to measure the three-dimensional shape of the measurement target object.

[0003] For example, a distance measuring method is known, which includes diffusing light rays respectively emitted from a plurality of light emitters by a diffusing plate, irradiating the diffused light rays onto a measurement target range, and detecting the reflected light rays by a light detector including light receiving / emitting portions two-dimensionally arranged. In this distance measuring method, the emitted light is diffused by the diffusion plate. Therefore, short-distance measurement can be performed within a certain light range. However, this distance measuring method is not suitable for long-distance measurement.

[0004] On the other hand, Patent Document 1 discloses a distance measuring method, which includes using a lens to collimate light rays emitted from a plurality of light emitters (forming the light rays into parallel light rays); and irradiating the entire irradiation range with light ray bundles respectively emitted from the plurality of light emitters. This method is suitable for long-distance measurement because the emitted light is formed into a light beam.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: US 2007 / 0181810 A1 Summary of the Invention

[0008] Technical Problem to be Solved by the Invention

[0009] However, a detector that detects light reflected from a measurement target object has the characteristic of having high light reception sensitivity for light entering from a direction perpendicular to the detector and low light reception sensitivity for light entering from a direction inclined to the detector. Therefore, there is a problem that the accuracy of distance measurement performed with respect to the surrounding portion in the measurement target range is reduced.

[0010] In view of the above circumstances, an object of the present technology is to provide a light-emitting element and a distance measuring device, the light-emitting element having a vertical cavity surface emitting laser structure and being suitable for long-distance light irradiation.

[0011] Solution to the Problem

[0012] To achieve the above object, a light-emitting element according to an embodiment of the present technology includes a plurality of light emitters, a first electrode terminal, and a second electrode terminal.

[0013] A plurality of light emitters are arranged one-dimensionally or two-dimensionally in a direction perpendicular to an optical axis corresponding to light emitted from each of the plurality of light emitters. Each of the plurality of light emitters is a vertical cavity surface emitting laser element. Each of the plurality of light emitters includes a first electrode and a second electrode, and each of the plurality of light emitters emits light due to a current flowing from the first electrode to the second electrode.

[0014] A first electrode terminal is electrically connected to the first electrode.

[0015] A second electrode terminal is electrically connected to the second electrode.

[0016] A current path passing through one of the plurality of light emitters from the first electrode terminal to the second electrode terminal exhibits a resistance different from a resistance of a current path passing through another one of the plurality of light emitters from the first electrode terminal to the second electrode terminal.

[0017] When viewed in a direction extending parallel to the optical axis, the light emitting element may have a central region and a peripheral region. The central region includes light emitters in an inner portion of the plurality of light emitters, and the peripheral portion includes light emitters in an outer peripheral portion of the plurality of light emitters, and

[0018] A current path passing through a light emitter included in the plurality of light emitters and in the central region may exhibit a higher resistance than a current path passing through a light emitter included in the plurality of light emitters and located in the peripheral region.

[0019] Each of the plurality of light emitters may include: a first distributed Bragg reflector (DBR) layer electrically connected to the first electrode; a second DBR layer electrically connected to the second electrode; a current confinement layer disposed between the first DBR layer and the second DBR layer; and an active layer disposed between the first DBR layer and the second DBR layer, and the active layer emits light due to a current confined by the current confinement layer.

[0020] The current confinement layer may have a confinement region and an injection region having a higher conductivity than the confinement region, and

[0021] The resistance of the current path of the light emitter in the plurality of light emitters may vary according to a size of an aperture diameter which is a diameter of the injection region.

[0022] Each of the plurality of light emitters may have a mesa structure in which at least the first DBR layer, the current confinement layer, and the active layer of the light emitter of the plurality of light emitters are spaced apart from at least the first DBR layer, the current confinement layer, and the active layer of an adjacent light emitter of the plurality of light emitters, and

[0023] The size of the aperture diameter can vary according to the size of the table diameter.

[0024] The wiring connecting the first electrode terminal to one of the plurality of light emitters can exhibit a resistance different from the resistance of the wiring connecting the first electrode terminal to another one of the plurality of light emitters.

[0025] When viewed from a direction extending parallel to the optical axis, the light-emitting element can have a central region and a peripheral region. The central region includes the light emitters in the inner portion among the plurality of light emitters, and the peripheral portion includes the light emitters in the outer peripheral portion among the plurality of light emitters, and

[0026] The wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and located in the central region can exhibit a resistance different from the resistance of the wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and located in the peripheral region.

[0027] The wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and located in the central region can exhibit a higher resistance than the wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and located in the peripheral region.

[0028] The wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and located in the central region can be longer than the wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and located in the peripheral region.

[0029] The plurality of light emitters can be arranged in a plurality of lines, and

[0030] The light emitters of the plurality of light emitters in each of the plurality of lines can be connected to a corresponding one of the plurality of wirings that extend from the first electrode.

[0031] The plurality of wirings can include a wiring that extends from the first electrode terminal through the peripheral region to the central region and a wiring that extends from the first electrode terminal to the peripheral region, and

[0032] The wiring extending to the central region and the wiring extending to the peripheral region can exhibit different resistances.

[0033] The wiring extending to the peripheral region can have a larger cross-sectional area than the wiring extending to the central region.

[0034] The first electrode included in one of the plurality of light emitters can exhibit a contact resistance different from the contact resistance of the first electrode included in another one of the plurality of light emitters.

[0035] Each of the plurality of light emitters may include: a first DBR layer electrically connected to a first electrode; a second DBR layer electrically connected to a second electrode; a current limiting layer disposed between the first DBR layer and the second DBR layer; and an active layer disposed between the first DBR layer and the second DBR layer and emitting light due to the current limited by the current limiting layer.

[0036] Each of the plurality of light emitters may have a mesa structure in which, using isolation grooves, at least the first DBR layer, the current limiting layer, and the active layer of the light emitters of the plurality of light emitters are spaced apart from at least the first DBR layer, the current limiting layer, and the active layer of adjacent light emitters of the plurality of light emitters, and

[0037] The isolation groove provided around one of the plurality of light emitters may have a depth different from the depth of the isolation groove provided around another of the plurality of light emitters.

[0038] To achieve the above object, a light emitting element according to an embodiment of the present technology includes a plurality of light emitters, a first electrode terminal, and a second electrode terminal.

[0039] The plurality of light emitters are a plurality of light emitters arranged one-dimensionally or two-dimensionally in a direction perpendicular to the optical axis corresponding to the light emitted from each of the plurality of light emitters. Each of the plurality of light emitters is a vertical cavity surface emitting laser element. Each of the plurality of light emitters includes a first electrode and a second electrode. Each of the plurality of light emitters emits light due to the current flowing from the first electrode to the second electrode.

[0040] The first electrode terminal is electrically connected to the first electrode.

[0041] The second electrode terminal is electrically connected to the second electrode.

[0042] One of the plurality of light emitters has a light extraction efficiency different from that of another of the plurality of light emitters.

[0043] When viewed in a direction extending parallel to the optical axis, the light emitting element may have a central region and a peripheral region. The central region includes the light emitters in the inner portion of the plurality of light emitters, and the peripheral portion includes the light emitters in the outer portion of the plurality of light emitters, and

[0044] The light emitters included in the plurality of light emitters and in the central region may have a lower light extraction efficiency than the light emitters included in the plurality of light emitters and in the peripheral region.

[0045] A surface coating may be formed on the light emitting surface of each of the plurality of light emitters, and

[0046] The surface coating of one of the plurality of light emitters may have a thickness different from that of the surface coating of another one of the plurality of light emitters.

[0047] A surface coating including a first region and a second region may be provided on the light-emitting surface of each of the plurality of light emitters, the second region having optical properties different from those of the first region, and

[0048] The position of the boundary between the first region and the second region in one of the plurality of light emitters may be different from the position of the boundary between the first region and the second region in another one of the plurality of light emitters.

[0049] Each of the plurality of light emitters may include: a first DBR layer electrically connected to a first electrode; a second DBR layer electrically connected to a second electrode; a current limiting layer disposed between the first DBR layer and the second DBR layer; and an active layer disposed between the first DBR layer and the second DBR layer and emitting light due to the current limited by the current limiting layer, and

[0050] The reflectivity of the first DBR layer of one of the plurality of light emitters and the reflectivity of the second DBR layer of one of the plurality of light emitters may be different from the reflectivity of the first DBR layer of another one of the plurality of light emitters and the reflectivity of the second DBR layer of another one of the plurality of light emitters, respectively.

[0051] The distribution of the light emission intensity of the plurality of light emitters from the central region to the peripheral region may have a shape represented by cos n θ.

[0052] To achieve the above object, a distance measuring device according to an embodiment of the present technology includes a plurality of light emitting units, a light receiving unit, and a distance measuring calculation unit.

[0053] The light emitting unit includes a light emitting element, and the light emitting element includes:

[0054] A plurality of light emitters arranged one-dimensionally or two-dimensionally in a direction perpendicular to the optical axis corresponding to the light emitted from each of the plurality of light emitters, each of the plurality of light emitters being a vertical cavity surface emitting laser element, each of the plurality of light emitters including a first electrode and a second electrode, and each of the plurality of light emitters emitting light due to the current flowing from the first electrode to the second electrode,

[0055] A first electrode terminal electrically connected to the first electrode, and

[0056] A second electrode terminal that is electrically connected to the second electrode, wherein

[0057] The current path from the first electrode terminal through one of the plurality of light emitters to the second electrode terminal exhibits a resistance different from that of the current path from the first electrode terminal through another of the plurality of light emitters to the second electrode terminal.

[0058] A light receiving unit that detects reflected light of light emitted from the light emitting unit.

[0059] A ranging calculation unit that calculates the distance to the measurement target based on the result of the detection performed by the light receiving unit. Description of the Drawings

[0060] Figure 1 is a block diagram showing the configuration of a ranging device according to an embodiment of the present technology.

[0061] Figure 2 is a schematic diagram showing the positional relationship among the light emitting unit, the light receiving unit, and the measurement target, where the light emitting unit and the light receiving unit are included in the ranging device.

[0062] Figure 3 is a schematic diagram of the light emitting unit.

[0063] Figure 4 is a perspective view of a light emitting element included in the light emitting unit.

[0064] Figure 5 is a schematic diagram showing the light emitted from the light emitting element.

[0065] Figure 6 is a cross-sectional view of the light emitting element.

[0066] Figure 7 is a cross-sectional view of a part of the configuration of the light emitting element.

[0067] Figure 8 is a plan view of a light emitter included in the light emitting element.

[0068] Figure 9 is a plan view of an anode included in the light emitting element.

[0069] Figure 10 is a plan view of a cathode included in the light emitting element.

[0070] Figure 11 is a schematic diagram showing the incident angle of reflected light on the light receiving unit included in the ranging device.

[0071] Figure 12 is a schematic diagram showing a (two-dimensional) region in the light emitting element.

[0072] Figure 13 It is a schematic diagram showing a (one-dimensional) region in a light-emitting element.

[0073] Figure 14 It is a circuit diagram showing an equivalent circuit of a light emitter in a light-emitting element.

[0074] Figure 15 It is a circuit diagram showing an equivalent circuit of a light emitter in a corresponding region in a light-emitting element.

[0075] Figure 16 It is a schematic diagram showing the aperture diameter of a light emitter included in a light-emitting element.

[0076] Figure 17 It is a graph showing the relationship between current and voltage caused by the aperture diameter of a light emitter.

[0077] Figure 18 It is a graph showing the relationship between current and light output caused by the aperture diameter of a light emitter.

[0078] Figure 19 It is a graph showing the relationship between voltage and light output caused by the aperture diameter of a light emitter.

[0079] Figure 20 It is a schematic diagram showing the aperture diameter of a light emitter for one region.

[0080] Figure 21 It is a schematic diagram showing the difference in aperture diameter between light emitters caused by the width of a restricted region.

[0081] Figure 22 It is a schematic diagram showing the difference in aperture diameter between light emitters caused by the mesa diameter.

[0082] Figure 23 It is a plan view showing the wiring connecting the anode in a light-emitting element to each light emitter.

[0083] Figure 24 It is a circuit diagram showing an equivalent circuit of a light emitter in a corresponding region in a light-emitting element, where wiring resistance has been added to the equivalent circuit.

[0084] Figure 25 It is a plan view showing the wiring connecting the anode in a light-emitting element to each light emitter.

[0085] Figure 26 It is a schematic diagram showing the contact area of the p-electrode and the depth of the separation groove in a light emitter.

[0086] Figure 27It is a schematic diagram showing the thickness of the surface coating on the light-emitting surface of the light emitter.

[0087] Figure 28 It is a graph showing the relationship between current and light output due to the thickness of the surface coating.

[0088] Figure 29 It is a schematic diagram showing the position of the boundary between the regions of the surface coating on the light-emitting surface of the light emitter.

[0089] Figure 30 It is a schematic diagram showing the position of the boundary between the regions of the surface coating on the light-emitting surface of the light emitter.

[0090] Figure 31 It is a graph showing the distribution of the luminous intensity of the light-emitting element (cos -1 θ: curve shape).

[0091] Figure 32 It is a graph showing the distribution of the luminous intensity of the light-emitting element (cos -3 θ: curve shape).

[0092] Figure 33 It is a graph showing the distribution of the luminous intensity of the light-emitting element (cos -5 θ: curve shape).

[0093] Figure 34 It is a graph showing the distribution of the luminous intensity of the light-emitting element (cos -7 θ: curve shape).

[0094] Figure 35 It is a graph showing the distribution of the luminous intensity of the light-emitting element (cos -1 θ: stepped shape).

[0095] Figure 36 It is a graph showing the distribution of the luminous intensity of the light-emitting element (cos -3 θ: stepped shape).

[0096] Figure 37 It is a graph showing the distribution of the luminous intensity of the light-emitting element (cos -5 θ: stepped shape).

[0097] Figure 38 It is a graph showing the distribution of the luminous intensity of the light-emitting element (cos -7 θ: stepped shape). Detailed implementation

[0098] Describes a ranging device according to an embodiment of the present technology.

[0099] [Configuration of the ranging device]

[0100] Figure 1 This is a block diagram showing the configuration of the distance measuring device 100 according to the present embodiment. As shown, the distance measuring device 100 includes a light emitting unit 101, a light emission controller 102, a light receiving unit 103, and a distance measurement calculation unit 104.

[0101] The light emitting unit 101 irradiates the measurement target P with irradiation light L whose brightness changes periodically. I When provided with a light emission control signal S by the light emission controller 102, the light emitting unit 101 generates the irradiation light L synchronously with the light emission control signal S. I The configuration of the light emitting unit 101 will be described later.

[0102] The light emission controller 102 controls the light emission of the light emitting unit 101. The light emission controller 102 generates a light emission control signal S and supplies the generated light emission control signal S to the light emitting unit 101 and the light receiving unit 103. The light emission control signal S can be, for example, a square wave with a frequency of 100 MHz.

[0103] The light receiving unit 103 receives the reflected light L R , which R is the light L reflected from the measurement target P I , and detects the amount of received light. The light receiving unit 103 receives a vertical synchronization signal and can detect the amount of light received in each period of the vertical synchronization signal every time the period of the vertical synchronization signal elapses. The vertical synchronization signal is, for example, a periodic signal with a period of 60 Hz. The light receiving unit 103 includes light receiving elements arranged in a two-dimensional grid and supplies image data G corresponding to the amount of light received by each light receiving element to the distance measurement calculation unit 104.

[0104] The distance measurement calculation unit 10 calculates the distance from the light receiving unit 103 to the measurement target P based on the image data G provided by the light receiving unit 103. The distance measurement calculation unit 104 can generate a depth map M in which the distance between each light receiving element and the measurement target P is represented by a gray value.

[0105] Figure 2 This is a schematic diagram showing the positional relationship between the light emitting unit 101, the light receiving unit 103, and the measurement target P. As shown, the light emitting unit 101 and the light receiving unit 103 are arranged adjacent to each other, and the distance between the light emitting unit 101 and the light receiving unit 103 is, for example, about several millimeters. The distance between each of the light emitting unit 101 and the light receiving unit 103 and the measurement target P ranges from about several tens of centimeters to about several meters. As will be described later, the light emitting unit 101 according to the present embodiment can irradiate the irradiation light L I over a long distance, and this enables long-distance measurement.

[0106] In the following, as Figure 2 shown, the Z direction represents the direction of the optical axis corresponding to the irradiation light L I and the X direction and the Y direction represent directions orthogonal to the Z direction and orthogonal to each other.

[0107] [Configuration of Light-Emitting Unit]

[0108] Figure 3 is a schematic diagram showing the configuration of the light-emitting unit 101. As shown, the light-emitting unit 101 includes a light-emitting element 111, a light-emitting element holder 112, a base 113, a collimating lens 114, and a lens holder 115.

[0109] The light-emitting element 111 includes a plurality of light emitters. Figure 4 is a perspective view of the light-emitting element 111. As shown, the light-emitting element 111 includes a plurality of light emitters 111a two-dimensionally arranged in a direction (X-Y direction) orthogonal to the optical axis direction (Z direction). In addition, the light emitters 111a may be arranged in a straight line parallel to a direction on the X-Y plane, that is, the light emitters 111a may be arranged one-dimensionally.

[0110] As Figure 3 shown, the light-emitting element 111 is fixed to the base 113 by the light-emitting element holder 112. The collimating lens 114 is supported by the lens holder 115 and collimates the outgoing light L I (forms the outgoing light L I into parallel light).

[0111] Figure 5 is a schematic diagram showing the irradiation light L I emitted from the light-emitting unit 101. The irradiation light L I is emitted from each light emitter 111a and then collimated by the collimating lens 114 to form a light beam, as shown. The irradiation light L I is formed into a light beam so that the irradiation light L I can reach a distant place. In addition, the orientation of the light beam passing through the peripheral portion of the collimating lens 114 is inclined by the light beam passing through the collimating lens 114. This enables irradiation over a wider range.

[0112] Note that the configuration of the light-emitting unit 101 is not limited to this. For example, a diffraction grating (diffractive optical element: DOE) may be arranged in front of the collimating lens 114 to diffract the irradiation light L I for tiling. This makes it possible to increase the number of irradiation points and further widen the irradiation range.

[0113] [Configuration of Light-Emitting Element]

[0114] Each of the plurality of light emitters 111a included in the light emitting element 111 is a vertical cavity surface emitting laser (VCSEL) element. Figure 6 is a cross-sectional view of a part of the light emitting element 111 and shows three light emitters 111a. Figure 7 is a cross-sectional view of the three light emitters 111a and omits the showing of a part of the configuration of the light emitting element 111.

[0115] As Figure 6 and Figure 7 shown, the light emitting element 111 includes a substrate 121, an n-type DBR layer 122, an n-type cladding layer 123, an active layer 124, a p-type cladding layer 125, a current confinement layer 126, a p-type DBR layer 127, a contact layer 128, an insulating layer 129, a p-type electrode 130, and an n-type electrode 131.

[0116] The substrate 121 supports each layer of the light emitting element 111. The substrate 121 can be, for example, an n-type gas substrate or can be made of another material.

[0117] The n-type DBR layer 122 is provided on the substrate 121 and serves as a distributed Bragg reflector (DBR) from which light of wavelength λ is reflected. The n-type DBR layer 122 and the p-type DBR layer 127 together form a resonator for emitting laser light.

[0118] The n-type DBR layer 122 can be formed by alternately stacking a low refractive index layer and a high refractive index layer multiple times. The low refractive index layer is made of, for example, n-type Al x1 Ga 1-X1 As (0 < X1 < 1), and the high refractive index layer is made of, for example, n-type Al x2 Ga 1-x2 As (0 < X2 < X1).

[0119] The n-type cladding layer 123 is stacked on the n-type DBR layer 122 and is a layer that confines light and current in the active layer 124. The n-type cladding layer 123 is made of, for example, n-type Al x3 Ga 1-x3 As (0 < X3 < 1).

[0120] The active layer 124 is provided on the n-type cladding layer 123 and emits spontaneous light and amplifies the spontaneous light. The active layer 124 is made of, for example, undoped In X4 Ga 1-X4 As or Al x4 Ga 1-x4 As (0 < X4 < 1).

[0121] The p-type cladding layer 125 is disposed on the active layer 124 and is a layer that confines light and current within the active layer 124. The p-type cladding layer 125 is made of, for example, p-type Al x5 Ga 1-x5 As (0 < X5 < 1).

[0122] The current confinement layer 126 is disposed on the p-type cladding layer 125 and has a current confinement effect. As Figure 7 shown, the current confinement layer 126 has a confinement region 126a and an injection region 126b. The confinement region 126a is made of, for example, oxidized AlAs and has a low conductivity and a low refractive index. The confinement region 126a serves as a light confinement region. The injection region 126b is made of, for example, unoxidized AlAs and is a region having a higher conductivity than the confinement region 126a.

[0123] The p-type DBR layer 127 is disposed on the current confinement layer 126 and serves as a DBR from which light of wavelength λ is reflected. The p-type DBR layer 127 and the n-type DBR layer 122 together form a resonator for the laser emission.

[0124] The p-type DBR layer 127 can be formed by alternately stacking a low refractive index layer and a high refractive index layer multiple times. The low refractive index layer is made of, for example, p-type Al x1 Ga 1-X6 As (0 < X6 < 1), and the high refractive index layer is made of, for example, p-type Al x7 Ga 1-x7 As (0 < X7 < X6).

[0125] The contact layer 128 is disposed on the p-type DBR layer 127 and is a layer that is joined to the p-type electrode 130. The contact layer 128 is made of, for example, p-type GaAs or p-type Al x8 Ga 1-x8 As (0 < X8 < 1).

[0126] As Figure 7 shown, the optical transmitter 111a includes a part of the n-type DBR layer 122, the n-type cladding layer 123, the active layer 124, the p-type cladding layer 125, the current confinement layer 126, the p-type DBR layer 127, and the contact layer 128, and is spaced apart from adjacent optical transmitters 111a using the isolation groove C. The optical transmitter 111a has a mesa (flat top) structure.

[0127] As Figure 6 shown, the insulating layer 129 is formed on the inner peripheral surface of the isolation groove C and insulates adjacent optical transmitters 111a. The insulating layer 129 is made of, for example, SiO2.

[0128] The p-type electrode 130 is formed on the contact layer 128 and the insulating layer 129 and serves as the p-type electrode for each light emitter 111a. The p-type electrode 130 is made of any conductive material.

[0129] The n-type electrode 131 is formed on the substrate 121 and serves as the n-type electrode for each light emitter 111a. The n-type electrode 131 is made of any conductive material.

[0130] Figure 8 One light emitter 111a is shown as viewed from the light emission direction (Z direction). As shown, the peripheral portion of the surface of the contact layer 128 is covered by the p-type electrode 130. The central portion of the surface of the contact layer 128 is not covered by the p-type electrode 130 and is the surface from which the laser light generated by the light emitter 111a exits. As Figure 6 and Figure 8 shown, this surface is hereinafter referred to as the "light emission surface H". Note that a surface coating for controlling optical characteristics can be provided to the light emission surface H, as described later.

[0131] Figure 9 is a plan view of the front surface of the light-emitting element 111. As shown, the anode 141 is provided as a "first electrode terminal" at each of the two ends of the front surface of the light-emitting element 111. The anode 141 is the part to which the drive source of the light-emitting element 111 is connected by, for example, wire bonding, and the p-type electrode 130 included in each light emitter 111a is connected to the anode 141. The configuration of the anode 141 is not limited to Figure 9 the configuration shown, and any configuration that enables electrical connection of the drive source to the p-type electrode 130 can be adopted.

[0132] Figure 10 is a plan view of the back surface of the light-emitting element 111. As shown, the cathode 151 is provided as a "second electrode terminal" on the back surface of the light-emitting element 111. The cathode 151 is the part to which the ground wiring of the light-emitting element 111 is connected by solder connection or using a conductive adhesive, and the n-type electrode 131 included in each light emitter 111a is connected to the cathode 151. The configuration of the cathode 151 is not limited to Figure 10 the configuration shown, and any configuration that enables electrical connection of the ground potential of the light-emitting element 111 to the n-type electrode 131 can be adopted.

[0133] The light-emitting element 111 has the above configuration. Note that the configuration of the light-emitting element 111 is not limited to this, and any configuration in which each light emitter 111a serves as a VCSEL can be adopted. For example, the light-emitting element 111 can be a VCSEL in which the light emission direction is the substrate direction, that is, a so-called back-emission VCSEL.

[0134] [Operation of the Light-Emitting Element]

[0135] When a voltage is applied between the anode 141 and the cathode 151, current flows from the p-type electrode 130 through each light emitter 111a to the n-type electrode 131. Due to the limiting effect of the current limiting layer 126, the current is injected through the injection region 126b.

[0136] Due to the injected current, self-luminescence is generated in the region of the active layer 124 adjacent to the injection region 126b. The self-luminescence travels in the stacking direction (Z direction) of the light-emitting element 111 and is reflected by the n-type DBR layer 122 and the p-type DBR layer 127.

[0137] The n-type DBR layer 122 and the p-type DBR layer 127 are configured such that light of the oscillation wavelength λ is reflected by the n-type DBR layer 122 and the p-type DBR layer 127. From the self-luminescence, the component of the oscillation wavelength λ forms a standing wave between the n-type DBR layer 122 and the p-type DBR layer 127 and is amplified by the active layer 124.

[0138] When the value of the injected current exceeds the threshold, the light forming the standing wave is lasered and is transmitted through the p-type cladding layer 125, the current limiting layer 126, the p-type DBR layer 127, and the contact layer 128 to exit from the light exit surface H. Accordingly, light corresponding to the optical axis in the Z-axis direction exits from each light emitter 111a, and the light L I exits from the light-emitting unit 101 (refer to Figure 5 ).

[0139] [Regarding the distribution of the light-emitting intensity]

[0140] As described above, in the distance measuring device 100, the irradiation light L I exits from the light-emitting unit 101, and the light receiving unit 103 receives the reflected light L reflected from the measurement target P R to measure the distance to the measurement target P. Figure 11 is a schematic diagram showing the incident angle of the reflected light L R .

[0141] The light-emitting element 111 according to the present embodiment is configured such that the intensities of the plurality of irradiation lights L I emitted by the corresponding light emitters 111a (hereinafter referred to as the light-emitting intensities) are non-uniform, and the plurality of irradiation lights L I have a specific light-emitting intensity distribution. If the corresponding light emitters 111a have uniform light-emitting intensities, the irradiation points formed by the collimating lens 114 will also have uniform brightness.

[0142] Here, the light receiving unit 103 has a wide field of view for light entering from Figure 11the reflected light L therein R1 ) has a characteristic of higher light reception sensitivity than the light entering from a narrow field of view angle ( Figure 11 the reflected light L therein R2 ). Therefore, when the irradiation point has uniform brightness, the ranging performed with respect to the surrounding area in the measurement target range may be reduced in accuracy.

[0143] Figure 12 is a plan view of the light-emitting element 111 according to the present embodiment as viewed from the direction (Z direction) extending parallel to the optical axis corresponding to the outgoing light. As shown, the front surface of the light-emitting element 111 is divided into a plurality of regions called a first region A1, a second region A2, and a third region A3.

[0144] The first region A1 includes the light emitters 111a in the inner part among the plurality of light emitters 111a, and the first region A1 is a region in the central part of the light-emitting element 111. The third region A3 includes the light emitters 111a in the peripheral part among the plurality of light emitters 111a, and the third region is a region in the peripheral part of the light-emitting element 111. The second region A2 is a region between the first region A1 and the third region A3, and includes the light emitters 111a between the first region A1 and the third region A3.

[0145] The light-emitting element 111 is configured such that the third region A3 exhibits the highest light emission intensity, the second region A2 exhibits the second highest light emission intensity, and the first region A1 exhibits the lowest light emission intensity, as will be described later. This makes it possible to compensate for the reduction in light reception sensitivity for the light ( Figure 11 the reflected light L therein R1 ) entering the light receiving unit 103 from a wide field of view angle, and prevent the reduction in the accuracy of the ranging performed with respect to the surrounding area in the measurement target range.

[0146] In Figure 12 , the first region A1 to the third region A3 are distributed in two directions: the X direction and the Y direction, that is, distributed two-dimensionally. However, the first region A1 to the third region A3 may be distributed only in the X direction, that is, distributed one-dimensionally.

[0147] Figure 13 is a plan view of the first region A1 to the third region A3 distributed one-dimensionally. As shown, the first region A1 may be a region in the central part of the light-emitting element 111, the third region A3 may be a region in the peripheral part of the light-emitting element 111, and the second region A2 may be a region between the first region A1 and the third region A3.

[0148] Note that in the following description, the light emitter 111a included in the first area A1 is referred to as a first light emitter 111a1, the light emitter 111a included in the second area A2 is referred to as a second light emitter 111a2, and the light emitter 111a included in the third area A3 is referred to as a third light emitter 111a3. The number of the first light emitters 111a1, the number of the second light emitters 111a2, and the number of the third light emitters 111a3 are not particularly limited.

[0149] The light emitting element 111 has the following configuration to make a difference in the light emission intensity of the light emitter 111a between the first area A1, the second area A2, and the third area A3. Note that the number of areas into which the light emitting element 111 is divided is not limited to the above example.

[0150] <1. Difference in luminous intensity depending on resistance>

[0151] As described above, each light emitter 111 a is electrically connected to the anode 141 and the cathode 151 , and a current path from the anode 141 to the cathode 151 passing through each light emitter 111 a is formed between the anode 141 and the cathode 151 .

[0152] Figure 14 1 is a circuit diagram showing an equivalent circuit of a current path in one light emitter 111a. In the figure, the power supply potential (Vcc) is the potential of the anode 141, and the ground potential (GND) is the potential of the cathode 151. The resistance Rf is the resistance between the light emitter 111a and the anode 141, and the resistance Rb is the resistance between the light emitter 111a and the cathode 151. As shown, the current path from the anode 141 through the light emitter 111a to the cathode 151 is referred to as a current path E, and the resistance of the current path E is referred to as a path resistance R. E .

[0153] Figure 15 1 is a circuit diagram showing an equivalent circuit of current paths of the first light emitter 111a1, the second light emitter 111a2, and the third light emitter 111a3. As shown, the current path from the anode 141 through the first light emitter 111a1 to the cathode 151 is referred to as the first current path E1. Similarly, the current path through the second light emitter 111a2 is referred to as the second current path E2, and the current path through the third light emitter 111a3 is referred to as the third current path E3.

[0154] like Figure 15As shown, the resistor Rf in the first current path E1 is referred to as resistor Rf1, the resistor Rf in the second current path E2 is referred to as resistor Rf2, and the resistor Rf in the third current path E3 is referred to as resistor Rf3. Additionally, the resistor Rb in the first current path E1 is referred to as resistor Rb1, the resistor Rb in the second current path E2 is referred to as resistor Rb2, and the resistor Rb in the third current path E3 is referred to as resistor Rb3.

[0155] The resistance of the entire first current path E1 is obtained by summing the resistor Rf1 and the resistor Rb1, and the resistance of the entire second current path E2 is obtained by summing the resistor Rf2 and the resistor Rb2. The resistance of the entire third current path E3 is obtained by summing the resistor Rf3 and the resistor Rb3. Hereinafter, the resistance of the entire first current path E1 is referred to as the first path resistance R E1 , the resistance of the entire second current path E2 is referred to as the second path resistance R E2 , and the resistance of the entire current path E3 is referred to as the third path resistance R E3 .

[0156] On the front surface of the light-emitting element 111, the current path in the region located closer to the center of the front surface exhibits a higher resistance. In other words, the first path resistance R E1 , the second path resistance R E2 , and the third path resistance R E3 are different from each other, where the first path resistance R E1 is higher than the second path resistance R E2 , and the second path resistance R E2 is higher than the third path resistance R E3 .

[0157] A larger current flows through the current path that exhibits a lower path resistance R E , and this causes the light emitter 111a to exhibit a higher luminous intensity. Therefore, the third light emitter 111a3 exhibits the highest luminous intensity, the second light emitter 111a2 exhibits the second highest luminous intensity, and the first light emitter 111a1 exhibits the lowest luminous intensity.

[0158] This makes it possible to compensate for the reduction in light reception sensitivity for light ([ Figure 11 the reflected light L in R1 ) that enters the light receiving unit 103 from a wide viewing angle, and to prevent a reduction in the accuracy of ranging performed with respect to the surrounding area within the measurement target range.

[0159] The following describes a method for making the first path resistance R R1 , the second path resistance R E2 , and the third path resistance RE3 Specific methods for generating differences

[0160] {1-1. Control of path resistance using the OA diameter}

[0161] In the light-emitting element 111, it is possible to cause a difference in the resistance of the current path by controlling the internal resistance of each light emitter 111a using the aperture diameter (optical aperture (OA) diameter) of the light emitter 111a.

[0162] Figure 16 is a cross-sectional view that is part of the configuration of the light emitter 111a and shows the OA diameter D. As shown, the OA diameter D is the diameter of the injection region 126b of the current limiting layer 126. In the light emitter 111a, the current applied to the light emitter 111a is injected through the injection region 126b, and self-luminescence is generated in the region adjacent to the injection region 126b in the active layer 124. In other words, the injection region 126b serves as an optical aperture.

[0163] Figure 17 is a graph showing the relationship between voltage and current for each OA diameter of the light emitter 111a. As indicated by the arrow in the figure, the voltage required to make the same amount of current flow decreases as the OA diameter increases.

[0164] Figure 18 is a graph showing the relationship between current and light output for each OA diameter of the light emitter 111a. As indicated by the arrow in the figure, the saturated light output increases as the OA diameter increases, but when the light output is less than the saturated light output, the light output remains the same regardless of the OA diameter for the same amount of current.

[0165] Figure 19 is a graph showing the relationship between voltage and light output for each OA diameter of the light emitter 111a. As indicated by the arrow in the figure, the light output at the same voltage increases as the OA diameter increases.

[0166] Therefore, in the light-emitting element 111, the OA diameter of the light emitter 111a is different among the regions as the first region A1 to the third region A3, and this makes it possible to control the difficulty of current flow due to voltage (i.e., the resistance of the light emitter 111a), and to make the path resistance R E generate differences.

[0167] Specifically, the OA diameter of the third light emitter 111a3 is made the largest, the OA diameter of the second light emitter 111a2 is made the second largest, and the OA diameter of the first light emitter 111a1 is made the smallest. Figure 20It is a schematic diagram showing the OA diameters D of the first light emitter 111a1 to the third light emitter 111a3. As shown, the OA diameter D3 of the third light emitter 111a3 is greater than the OA diameter D2 of the second light emitter 111a2, and the OA diameter D2 of the second light emitter 111a2 is greater than the OA diameter D1 of the first light emitter 111a1. For example, the OA diameter D3 can be 9 μm, the OA diameter D2 can be 8 μm, and the OA diameter D1 can be 7 μm.

[0168] Therefore, the first path resistance R E1 is the highest, the second path resistance R E2 is the second highest, and the third path resistance R E3 is the lowest. Accordingly, the third light emitter 111a3 exhibits the highest luminous intensity, the second light emitter 111a2 exhibits the second highest luminous intensity, and the first light emitter 111a1 exhibits the lowest luminous intensity.

[0169] The method for changing the width of the restricted area 126a measured from the outer periphery of the mesa structure is a method for creating a difference in the OA diameter between the light emitters 111a. Figure 21 It is a schematic diagram showing the difference in the width of the restricted area 126a. As shown, the width of the restricted area 126a of the first light emitter 111a1 is referred to as width Wa1, the width of the restricted area 126a of the second light emitter 111a2 is referred to as width Wa2, and the width of the restricted area 126a of the third light emitter 111a3 is referred to as width Wa3.

[0170] Note that the width Wb of the mesa structure of the corresponding light emitter 111a is the same. Here, by making width Wa3 smaller than width Wa2, and by making width Wa2 smaller than width Wa1, the OA diameter D3 can be made the largest and the OA diameter D1 can be made the smallest.

[0171] The restricted area 126a can be formed by performing an oxidation process after stacking the layers forming the current limiting layer 126. In this case, it is possible to create a difference in the width of the restricted area 126a between the first region A1 to the third region A3 by adjusting the time for the oxidation process or another condition for the oxidation process.

[0172] In addition, the method for changing the diameter of the mesa structure (hereinafter referred to as the mesa diameter) is another method for creating a difference in the OA diameter between the light emitters 111a. Figure 22A schematic diagram showing the difference in the mesa diameters is presented. As shown, the mesa diameter of the first light emitter 111a1 is referred to as diameter Wb1, the mesa diameter of the second light emitter 111a2 is referred to as diameter Wb2, and the mesa diameter of the third light emitter 111a3 is referred to as diameter Wb3.

[0173] Note that the width Wa of the confinement region 126a of the corresponding light emitter 111a is the same. Here, by making diameter Wa3 larger than diameter Wa2 and by making diameter Wa2 smaller than diameter Wa1, the OA diameter D3 can be maximized and the OA diameter D1 can be minimized.

[0174] The diameter of the mesa structure can be adjusted by the position where the isolation groove C (refer to Figure 7 ) is formed or by the width of the isolation groove C. This method enables the OA diameter to be changed while the width Wa of the confinement region 126a in the first region A1 to the third region A3 is the same. This allows the same oxidation treatment conditions as those performed to form the confinement regions 126a of the first region A1 and the third region A3.

[0175] In addition, the diameter OA of the light emitter 111a between the first region A1 to the third region A3 can be made different by changing both the width Wa of the confinement region 126a and the mesa diameter Wb.

[0176] {1-2. Control of the path resistance performed using the wiring resistance}

[0177] In the light-emitting element 111, for example, a wiring electrode structure in which the electrodes are arranged in separated straight lines is adopted instead of a structure including an electrode that uniformly covers the entire light-emitting element 111 to connect the anode 141 included in each light emitter 111a to the p-type electrode 130, and it is possible to use the resistance of the wiring to make the first path resistance R R1 、the second path resistance R E2 and the third path resistance R E3 different from each other.

[0178] Figure 23 A schematic diagram showing the wiring L that connects the light emitters 111a located at both ends of the light-emitting element 111 to the anode 141 is presented. As shown, the light emitters 111a are arranged in multiple lines in the X direction. Multiple wirings L extend in the X direction from the anode 141 located at both ends, and the light emitters 111a in each line are connected in series to the wiring L. Note that the wiring L can be Figure 6 the p-type electrode 130 formed between the light emitters 111a in

[0179] In this configuration, asFigure 13 As shown, when the first region A1, the second region A2, and the third region A3 are arranged one-dimensionally, the light emission intensity of the third region A3 can be made the highest, and the light emission intensity of the first region A1 can be made the lowest. In each wiring L, the wiring L between the anode 141 and the second region A2 is referred to as a wiring portion La, and the wiring L between the first region A1 and the third region A3 is referred to as a wiring portion Lb, as Figure 23 shown. In addition, the wiring L between the second regions A2 is referred to as a wiring portion Lc.

[0180] Although the wiring L is made of a conductive material, the wiring L exhibits some resistance. Hereinafter, the resistance of the wiring portion La is referred to as a resistance RLa, and the resistance of the wiring portion Lb is referred to as a resistance RLb.

[0181] Figure 24 is a circuit diagram of the light-emitting element 111. As shown, by summing the resistance Rf3 and the resistance Rb3, a third path resistance R corresponding to the resistance of the third current path E3 is obtained E3 . On the other hand, by summing the resistance RLa, the resistance Rf2, and the resistance Rb2, a second path resistance R corresponding to the resistance of the second current path E2 is obtained E2 because there is a wiring portion La in the current path between the anode 141 and the second light emitter 111a2.

[0182] In addition, by summing the resistance RLa, the resistance Rf2, and the resistance Rb2, a first path resistance R corresponding to the resistance of the first current path E1 is obtained E1 because there are a wiring portion La and a wiring portion Lb in the current path between the anode 141 and the first light emitter 111a1.

[0183] As described above, the wiring L between the anode 141 at each of the two ends and the third light emitter 111a3 adjacent to the anode 141 is short, and the third path resistance R E3 is low. On the other hand, the wiring L (wiring portion La) between the anode 141 at each of the two ends and the second light emitter 111a2 located at a position far from the anode 141 is long, and the second path resistance R E2 is high.

[0184] In addition, the wiring L (wiring La + wiring Lb) between the anode 141 at each of the two ends and the first light emitter 111a1 located at the position farthest from the anode 141 is longer, and the first path resistance R E1Highest. As described above, it is possible to create a difference in the path resistance R between regions by creating a difference between the first region A1, the second region A2, and the third region A3 along the length of the wiring L located between the anode 141 and the light emitter 111a. E Create a difference.

[0185] Note that the wiring L does not have to have the same cross-sectional area. For example, the wiring portion La can have a larger cross-sectional area than the wiring portion Lb, and the wiring portion Lb can have a larger cross-sectional area than the wiring portion Lc. The cross-sectional area of the wiring L can be adjusted by changing at least one of the width and thickness of the wiring L.

[0186] In addition, in the light-emitting element 111, as Figure 12 shown, when the first region A1, the second region A2, and the third region A3 are arranged two-dimensionally, the light-emitting intensity of the third region A3 can be made the highest, and the light-emitting intensity of the first region A1 can be made the lowest. Figure 25 is a schematic diagram showing the wiring L connecting the light emitter 111a and the anode 141 located at both ends of the light-emitting element 111. As shown, the light emitters 111a are arranged in multiple straight lines in the X direction, and the multiple wirings L extend from the anodes 141 located at both ends in the X direction. The light emitters 111a in each straight line are connected in series to the wiring L.

[0187] Here, the wiring L includes the wiring L1, the wiring L2, and the wiring L3. The wiring L1 is the wiring that extends through the third region A3 and the second region A2 to the first region A1, and the wiring L2 is the wiring that extends through the third region A3 to the second region A2. The wiring L3 is the wiring that extends to the third region A3. Note that the number of the wiring L1, the number of the wiring L2, and the number of the wiring L3 can be set arbitrarily and is not limited to Figure 25 the number shown.

[0188] The wiring L1, the wiring L2, and the wiring L3 exhibit different resistances, where the wiring L3 exhibits the lowest resistance and the wiring L1 exhibits the highest resistance. The resistances of the wiring L1, the wiring L2, and the wiring L3 can be controlled by their cross-sectional areas, where the wiring L3 can have a larger cross-sectional area than the wiring L2, and the wiring L2 can have a larger cross-sectional area than the wiring L1.

[0189] The cross-sectional area of the wiring L can be adjusted by changing at least one of the width and thickness of the wiring L. As Figure 25 shown, the wiring L can have a uniform thickness, the wiring L3 can have a larger width than the wiring L2, and the wiring L2 can have a larger width than the wiring L1.

[0190] In addition, the wiring L may have a uniform width, the wiring L3 may have a greater thickness than the wiring L2, and the wiring L2 may have a greater thickness than the wiring L1. Further, both the thickness and width of the wiring L may be adjusted such that the wiring L3 has a greater cross-sectional area than the wiring L2, and the wiring L2 has a greater cross-sectional area than the wiring L1. Note that the wiring L is not limited to three types of wirings, i.e., the wirings L1, L2, and L3 having different cross-sectional areas, and the wiring L may be two types of wirings, or four or more types of wirings.

[0191] In this configuration, in the X direction in which the wiring L extends, the length of the wiring L that connects each light emitter 111a to the anode 141 is used to increase the path resistance R in the central portion. E In addition, in the Y direction, the difference in the resistance of the wiring L is used to increase the path resistance R in the central portion. E Therefore, when the first region A1, the second region A2, and the third region A3 are arranged two-dimensionally, the first path resistance R E1 can be made the highest, the second path resistance R E2 the second highest, and the third path resistance R E3 the lowest.

[0192] As described above, the light-emitting element 111 in which the surrounding region (the third region A3) exhibits a higher light-emitting intensity than the central region (the first region A1) can be set by creating a difference in the path resistance R among the first region A1, the second region A2, and the third region A3 by using the resistance of the wiring L. In this configuration, the corresponding light emitters 111a have the same configuration. Therefore, a distribution of the light-emitting intensity can be formed only by changing the wiring width under the condition that the conditions for obtaining the corresponding light emitters 111a are the same. E Note that

[0193] Note that Figure 23 and Figure 25 show examples of setting the wiring L that connects a plurality of light emitters 111a. However, a planar electrode (solid pattern electrode) may be provided instead of the wiring L. In this case, it is possible to create a difference in the path resistance by different wiring resistances from the anode 141 to the corresponding light emitters 111a.

[0194] {1-3. Control of Path Resistance Performed Using Contact Resistance}

[0195] In addition, in the light-emitting element 111, it is also possible to create a difference in the path resistance R by using the contact resistance (i.e., the resistance between the semiconductor and the metal interface) in each light emitter 111a. E create a difference.

[0196] Figure 26It is a cross-sectional view of the optical transmitter 111a. As Figure 26 and Figure 8 shown, the contact area between the p-type electrode 130 in contact with the contact layer 128 can be changed by adjusting the width Wp of the p-type electrode 130. This makes it possible to increase or decrease the resistance Rf in the optical transmitter 111a (refer to Figure 14 ), and to create a difference between the first path resistance R R1 , the second path resistance R E2 and the third path resistance R E3 .

[0197] Specifically, the width Wp in the third optical transmitter 111a3 can be set to a specific width to set the resistance Rf3 (refer to Figure 15 ). In addition, the width Wp in the second optical transmitter 111a2 can be smaller than the width Wp in the third optical transmitter 111a3, such that the resistance Rf2 exhibits a larger value than the resistance Rf3. Furthermore, the width Wp in the first optical transmitter 111a1 can be smaller than the width Wp in the second optical transmitter 111a2, such that the resistance Rf1 exhibits a larger value than the resistance Rf2.

[0198] In addition, in addition to controlling the width Wp, the resistance Rf can be increased or decreased by changing the shape of the p-type electrode 130 and adjusting the contact area between the p-type electrode 130 and the contact layer 128.

[0199] Furthermore, as Figure 26 shown, the resistance Rb (refer to Figure 7 ) can be increased or decreased by adjusting the depth M of the separation groove C (refer to Figure 14 ), and this makes it possible to create a difference between the first path resistance R R1 , the second path resistance R E2 and the third path resistance R E3 .

[0200] Specifically, the depth M of the separation groove C located at the position surrounding the third optical transmitter 111a3 can be set to a specific depth to set the resistance Rb3 (refer to Figure 15 ). In addition, the depth M of the separation groove C located at the position surrounding the second optical transmitter 111a2 can be greater than the depth M of the separation groove C located at the position surrounding the third optical transmitter 111a3, such that the resistance Rb2 exhibits a larger value than the resistance Rb3. Furthermore, the depth M of the separation groove C located at the position surrounding the first optical transmitter 111a1 can be greater than the depth M of the separation groove C located at the position surrounding the second optical transmitter 111a2, such that the resistance Rb1 exhibits a larger value than the resistance Rb2.

[0201] In addition, it is also possible to change both the width Wp and the depth M of the first light emitter 111a1, the second light emitter 111a2, and the third light emitter 111a3, such that the first path resistance R R1 is the highest, and the third path resistance R E3 is the lowest.

[0202] The above adjustment of the width Wp and the depth M enables a difference in the path resistance R E to be generated between the first region A1, the second region A2, and the third region A3. This configuration also enables a distribution of the emission intensity to be formed using only the shape of the p-type electrode 130 or the depth of the isolation groove C in the case where the corresponding light emitters 111a have a uniform stacked structure.

[0203] As described above, the light-emitting element 111 in which the surrounding region (third region A3) exhibits a higher emission intensity than the central region (first region A1) can be provided using the difference in the path resistance R E between the first region A1, the second region A2, and the third region A3.

[0204] Note that, regarding the method for generating a difference in the path resistance R R1 between the first path resistance R E2 and the third path resistance R E3 and the path resistance R E among them, it is possible to use only one of the above controls performed using the OA diameter, the control performed using the wiring resistance, and the control performed using the contact resistance, or it is possible to use two or more of them in combination. For example, a one-dimensional distribution of the emission intensity (refer to Figure 13 ) can be formed by performing the control using the wiring resistance, and then a two-dimensional distribution of the emission intensity (refer to Figure 12 ) can be formed by performing the control using the OA diameter.

[0205] In addition, the light-emitting element 111 in which the first path resistance R R1 is the highest, the second path resistance R E2 is the second highest, and the third path resistance R E3 is the lowest can also be provided by a method different from the above corresponding methods, such as changing the material of the wiring L.

[0206] <2. Difference in Emission Intensity due to Light Extraction Efficiency>

[0207] In the light-emitting element 111, it is possible to cause a difference in the emission intensity between the first region A1, the second region A2, and the third region A3 by controlling the light extraction efficiency of the light emitter 111a (refer to Figure 12 and 13) Note that when there are differences in the emission intensity due to the light extraction efficiency of the light emitter 111a, the above-mentioned path resistance of the light emitter 111a can be the same.

[0208] Specifically, in the light-emitting element 111, the light extraction efficiencies of the light emitters 111a in the first region A1, the second region A2, and the third region A3 are different from each other, and the light emitter 111a has a higher light extraction efficiency in the region closer to the center of the front surface of the light-emitting element 111. In other words, the third light emitter 111a3 has the highest light extraction efficiency, the second light emitter 111a2 included in the second region A2 has the second-highest light extraction efficiency, and the first light emitter 111a1 has the lowest light extraction efficiency. Therefore, the third region A3 exhibits the highest emission intensity, the second region A2 exhibits the second-highest emission intensity, and the first region A1 exhibits the lowest emission intensity.

[0209] This makes it possible to compensate for the reduction in the light reception sensitivity for the light ( Figure 11 reflected light L in R1 ) entering the light reception unit 103 from a wide viewing angle, and to prevent a reduction in the accuracy of the distance measurement performed with respect to the surrounding area within the measurement target range, as described above.

[0210] The specific structure that causes differences in the light extraction efficiency of the light emitter 111a will be described below.

[0211] {2-1. Control of light extraction efficiency performed using the thickness of the surface coating}

[0212] In the light-emitting element 111, it is possible to cause differences in the light extraction efficiency of the light emitter 111a using the thickness of the surface coating included in each light emitter 111a.

[0213] Figure 27 is a magnified cross-sectional view of the light emitter 111a and shows the surface coating 135 included in the light emitter 111a. As shown, the surface coating 135 is formed on the contact layer 128. The surface coating 135 is an optical thin film for controlling the reflectance of the light output surface H and can be made of, for example, SiN. A change in the thickness T of the surface coating 135 makes it possible to change the threshold current and the slope efficiency, and this results in a change in the light output at a specific current value.

[0214] Figure 28 is a graph showing an example of the relationship between the thickness T of the surface coating 135 and the light output. As shown, due to the thickness T of the surface coating 135, the light output of the light emitter 111a is changed, that is, the light extraction efficiency can be adjusted. Note that Figure 28An example is shown where the light output decreases due to an increase in the thickness T, but the light extraction efficiency can change periodically due to the thickness T, and a decrease in the thickness T can cause an increase in the light output.

[0215] In the light-emitting element 111, the light extraction efficiency in the third region A3 can be maximized, the light extraction efficiency in the second region A2 can be the second highest, and the light extraction efficiency in the first region A1 can be the lowest by creating a difference in the thickness T of the surface coating 135 between the first light emitter 111a1, the second light emitter 111a2, and the third light emitter 111a3.

[0216] Therefore, the third region A3 exhibits the highest light-emitting intensity, the second region A2 exhibits the second highest light-emitting intensity, and the first region A1 exhibits the lowest light-emitting intensity. This makes it possible to provide a light-emitting element 111 in which the surrounding region exhibits a higher light-emitting intensity than the central region. In this configuration, except for the thickness of the surface coating 135, the corresponding light emitters 111a have the same configuration. Therefore, it is possible to form a distribution of the light-emitting intensity by preparing the thickness of the surface coating 135 under the same conditions for obtaining the corresponding light emitters 111a.

[0217] {2-2. Control of light extraction efficiency performed using the position of the boundary in the surface coating}

[0218] In the light-emitting element 111, the position of the boundary in the surface coating of each light emitter 111a can be used to create a difference in the light extraction efficiency of the light emitter 111a.

[0219] Figure 29 is an enlarged cross-sectional view of the light emitter 111a and shows the surface coating 136 and the surface coating 137 included in the light emitter 111a. As Figure 29 shown in (a) and (b) of, the surface coating 136 is formed on the contact layer 128, and the surface coating 137 is formed on a partial region of the surface coating 136. The surface coating 136 and the surface coating 137 are optical thin films for controlling the reflectance of the light-emitting surface H and can be made of, for example, SiN.

[0220] On the light-emitting surface H, the region where the surface coating 136 and the surface coating 137 are formed is called the region Ha, and on the light-emitting surface H, the region where only the surface coating 136 is formed is called the region Hb. In addition, the boundary between the region Ha and the region Hb is called the boundary K.

[0221] Figure 30 is a schematic diagram showing the region Ha and the region Hb, where Figure 30 the (a) of is Figure 29 the plan view of the (a) of, andFigure 30 The (b) of Figure 29 is a plan view of the (b). In the optical transmitter 111a, the oscillation mode of light can be switched by the position of the boundary K, and the threshold current and slope efficiency can be changed. Therefore, it is possible to maximize the light extraction efficiency in the third region A3, make the light extraction efficiency in the second region A2 the second highest, and make the light extraction efficiency in the first region A1 the lowest by making a difference in the position of the boundary K between the first optical transmitter 111a1, the second optical transmitter 111a2, and the third optical transmitter 111a3, as shown in Figure 29 the (a) and (b) of Figure 30 the (a) and (b) of

[0222] Therefore, the third region A3 exhibits the highest light emission intensity, the second region A2 exhibits the second highest light emission intensity, and the first region A1 exhibits the lowest light emission intensity. This makes it possible to provide a light-emitting element 111 in which the surrounding region exhibits a higher light emission intensity than the central region. In addition, in this configuration, except for the configuration of the surface coating, the corresponding optical transmitters 111a have the same configuration. Therefore, it is possible to form a distribution of light emission intensity by preparing the position of the boundary of the surface coating under the same conditions for obtaining the corresponding optical transmitters 111a.

[0223] Note that the regions Ha and Hb are not limited to regions with different numbers of surface coatings. The regions Ha and Hb can be regions where the surface coatings have different optical properties, such as regions where the surface coatings have different thicknesses, or regions where the surface coatings are made of different materials. The number of regions is also not limited to two, and can be three or more.

[0224] {2-3. Control of Light Extraction Efficiency by Using Reflectivity of DBR Layer}

[0225] In the light-emitting element 111, the light extraction efficiency of the optical transmitter 111a can also be made different by using one or both of the reflectivity of the n-type DBR layer 122 and the reflectivity of the p-type DBR layer 127.

[0226] As described above, when a voltage is applied between the anode 141 and the cathode 151 in the light emitter 111a, the self-emitted light emitted by the active layer 124 is reflected from the n-type DBR layer 122 and the p-type DBR layer 127, and is irradiated with laser light to be emitted from the light exit surface H. Therefore, the light extraction efficiency in the third region A3 can be maximized, the light extraction efficiency in the second region A2 can be the second highest, and the light extraction efficiency in the first region A1 can be the lowest by making the reflectance of the n-type DBR layer 122 and the reflectance of the p-type DBR layer 127 in the light emitter 111a different between the first light emitter 111a1, the second light emitter 111a2, and the third light emitter 111a3.

[0227] Accordingly, the third region A3 exhibits the highest light emission intensity, the second region A2 exhibits the second highest light emission intensity, and the first region A1 exhibits the lowest light emission intensity. This makes it possible to provide the light emitting element 111 in which the surrounding region exhibits a higher light emission intensity than the central region.

[0228] As described above, the light emitting element 111 in which the surrounding region exhibits a higher light emission intensity than the central region can be provided by using the difference in light extraction efficiency between the first region A1, the second region A2, and the third region A3.

[0229] Note that, with respect to the method for making the light extraction efficiency different between the first light emitter 111a1, the second light emitter 111a2, and the third light emitter 111a3, only one of the above-described control performed using the thickness of the surface coating, the control performed using the position of the boundary in the surface coating, and the control performed using the DBR layer reflectance can be used, or two or more of them can be used in combination.

[0230] In addition, the light emitting element 111 in which the light extraction efficiency in the third region A3 is the highest, the light extraction efficiency in the second region A2 is the second highest, and the light extraction efficiency in the first region A1 is the lowest can also be provided by a method different from the above corresponding methods.

[0231] [Regarding the shape of the distribution of the light emission intensity]

[0232] An example of the distribution of the light emission intensity of the light emitting element 111 is described. Figure 31 is a graph showing an example of the distribution of the light emission intensity of the light emitting element 111. As shown, the distribution of the light emission intensity of the light emitter 111 shows that the first region A1 corresponding to the central region exhibits a low light emission intensity, and the third region A3 corresponding to the surrounding region exhibits a high light emission intensity.

[0233] Here, Figure 31 the shown distribution of the light emission intensity has cos-1 The shape represented by θ. The distribution of the light emission intensity of the light-emitting element 111 is not limited to having a shape represented by cos -1 the shape represented by θ, and advantageously, the distribution of the light emission intensity of the light-emitting element 111 has a shape represented by cos n the shape represented by θ. Figures 32 to 34 is a graph showing other examples of the distribution of the light emission intensity of the light-emitting element 111.

[0234] The distribution of the light emission intensity may have a shape represented by cos -3 the shape represented by θ, as Figure 32 shown, or may have a shape represented by cos -5 the shape represented by θ, as Figure 33 shown. Additionally, the distribution of the light emission intensity may have a shape represented by cos -7 the shape represented by θ, as Figure 34 shown.

[0235] Additionally, as Figures 31 to 34 shown, the distribution of the light emission intensity of the light-emitting element 111 is not limited to a curved shape. Figures 35 to 38 is a schematic diagram showing other examples of the distribution of the light emission intensity of the light-emitting element 111. As shown, the light distribution of the light emission intensity of the light-emitting element 111 may have a stepped shape approximately represented by cos n the shape represented by θ.

[0236] [Effects provided by the light-emitting element]

[0237] As described above, in the light-emitting element 111, the light emission intensity in the third region A3 can be made the highest, the light emission intensity in the second region A2 can be made the second highest, and the light emission intensity in the first region A1 can be made the lowest by controlling the resistance of the current path passing through each light emitter 111a or the efficiency of extracting the light emitted by each light emitter 111a. This makes it possible to compensate for the reduction in light reception sensitivity for light ( Figure 11 the reflected light L in R1 ) entering the light-receiving unit 103 from a wide viewing angle, and prevent a reduction in the accuracy of the distance measurement performed with respect to the surrounding area within the measurement target range. Additionally, there is no need to add components, increase component costs, and make component sizes larger to obtain this distribution of the light emission intensity.

[0238] In addition, when the corresponding light emitters 111a are commonly connected to the anode 141 and the cathode 151, the difference in path resistance or the difference in light extraction efficiency can be used to form the distribution of the emission intensity. In other words, there is no need to adjust the applied power by connecting to the anodes and cathodes of each individual light emitter 111a to form the distribution of the emission intensity. Therefore, there is no need to arrange multiple drive sources for the light emitters 111a, which can prevent the component cost from increasing due to this arrangement and prevent the ranging device 100 from becoming larger in size due to this arrangement.

[0239] In addition, the present technology is also effective when the anode and the cathode are connected to each individual light emitter 111a and the corresponding light emitters 111a are driven individually. There is a possibility that the driver for driving each light emitter 111a will not have the parameter for setting the power for the light emitter 111a, or only a unified parameter can be used. Even in this case, it is still possible to form the distribution of the emission intensity in the light emitting element 111 by supplying equal power to the anodes 141 and cathodes 151 for each light emitter 111a.

[0240] [Improvement]

[0241] In the above embodiment, there are differences in the emission intensity of the light emitters 111a among the three regions, i.e., the first region A1, the second region A2, and the third region A3 (refer to Figure 12 and 13 ). However, the number of regions is not limited to three, and the number of regions can be two or four or more. The light emitting element 111 in which the peripheral region of the light emitting element 111 exhibits a high emission intensity and the central region of the light emitting element 111 exhibits a low emission intensity regardless of the number of regions makes it possible to prevent a decrease in the accuracy of the ranging performed on the peripheral region in the measurement target range of the light receiving unit 103.

[0242] In addition, the example in which the n-type portion is located on one side of the substrate 121 ( Figure 6 the lower side in Figure 6 ) and the p-type portion is located on one side of the light emitting surface H ( Figure 6 the upper side in Figure 6 ) in the light emitting element 111 has been described above, but the positions of the n-type portion and the p-type portion can be reversed. In addition, a high-resistance substrate can be used as the substrate 121, a p-type layer and an n-type layer can be provided on the substrate 121, and both electrodes can be taken out from one side of the substrate 121. In addition, the light emitting element 111 can be a back-emitting VCSEL in which the emission direction is the substrate direction. In addition, the example of the GaAs substrate has been described in the above embodiment, but depending on the target emission wavelength, a GaN substrate or an InP substrate can be used.

[0243] Additionally, an example has been described above in which the light-emitting element 111 is included in the light-emitting unit 101 of the distance measuring device 100, but the light-emitting element 111 is not limited thereto. For example, the light-emitting element 111 can also be used as a light source for structured light of the distance measuring device, or can be applied to uniform illumination performed without using a diffusion plate.

[0244] In addition, in addition to being used for the distance measuring device, the light-emitting element 111 can also be used as a light source for illumination. The emission wavelength can correspond to infrared light, ultraviolet light, or visible light, and the light-emitting element 111 can also be applied to exposure. In this case, it is also possible to correct the angular dependence of the transmittance of the optical part (such as a lens) in the illumination optical system (in this case, the light intensity in the surrounding part where the light enters obliquely also tends to decrease).

[0245] At least two features of the present technology described above can also be combined. That is, the various features described in the corresponding embodiments can be arbitrarily combined regardless of the embodiments. In addition, the above various effects are not restrictive but merely illustrative, and other effects can be provided.

[0246] Note that the present technology can also adopt the following configuration.

[0247] (1) A light-emitting element, comprising:

[0248] A plurality of light emitters arranged one-dimensionally or two-dimensionally in a direction perpendicular to the optical axis corresponding to the light emitted from each of the plurality of light emitters, each of the plurality of light emitters being a vertical cavity surface emitting laser element, each of the plurality of light emitters including a first electrode and a second electrode, and each of the plurality of light emitters emitting light due to a current flowing from the first electrode to the second electrode;

[0249] A first electrode terminal electrically connected to the first electrode; and

[0250] A second electrode terminal electrically connected to the second electrode, wherein,

[0251] The current path from the first electrode terminal through one of the plurality of light emitters to the second electrode terminal exhibits a resistance different from the resistance of the current path from the first electrode terminal through another of the plurality of light emitters to the second electrode terminal.

[0252] (2) The light-emitting element according to (1), wherein,

[0253] When viewed in a direction extending parallel to the optical axis, the light-emitting element has a central region and a peripheral region. The central region includes light emitters that are in the inner part of the plurality of light emitters, and the peripheral region includes light emitters that are in the outer peripheral part of the plurality of light emitters. And

[0254] The current path passing through the light emitters included in the plurality of light emitters and in the central region exhibits a higher resistance than the current path passing through the light emitters included in the plurality of light emitters and in the peripheral region.

[0255] (3) The light-emitting element according to (1) or (2), wherein

[0256] Each light emitter of the plurality of light emitters includes:

[0257] A first distributed Bragg reflector (DBR) layer electrically connected to the first electrode,

[0258] A second DBR layer electrically connected to the second electrode,

[0259] A current confinement layer disposed between the first DBR layer and the second DBR layer, and

[0260] An active layer disposed between the first DBR layer and the second DBR layer and emitting light due to the current confined by the current confinement layer,

[0261] The current confinement layer has a confinement region and an injection region, and the injection region has a higher conductivity than the confinement region. And

[0262] The resistance of the current path of the light emitters among the plurality of light emitters varies according to the size of the aperture diameter that is the diameter of the injection region.

[0263] (4) The light-emitting element according to (3), wherein

[0264] Each light emitter of the plurality of light emitters has a mesa structure in which at least the first DBR layer, the current confinement layer, and the active layer of the light emitters among the plurality of light emitters are spaced apart from at least the first DBR layer, the current confinement layer, and the active layer of the adjacent light emitters of the plurality of light emitters. And

[0265] The size of the aperture diameter varies according to the size of the mesa diameter.

[0266] (5) The light-emitting element according to any one of (1) to (4), wherein

[0267] The wiring connecting the first electrode terminal to one of the plurality of light emitters exhibits a resistance different from that of the wiring connecting the first electrode terminal to the other light emitter among the plurality of light emitters.

[0268] (6) The light-emitting element according to (5), wherein

[0269] When viewed from a direction extending parallel to the optical axis, the light-emitting element has a central region and a peripheral region. The central region includes the light emitters in the inner portion of the plurality of light emitters, and the peripheral region includes the light emitters in the outer peripheral portion of the plurality of light emitters, and

[0270] The wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and located in the central region exhibits a resistance different from that of the wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and located in the peripheral region.

[0271] (7) The light-emitting element according to (6), wherein

[0272] The wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and located in the central region exhibits a higher resistance than the wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and located in the peripheral region.

[0273] (8) The light-emitting element according to (7), wherein

[0274] The wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and located in the central region is longer than the wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and located in the peripheral region.

[0275] (9) The light-emitting element according to (8), wherein

[0276] The plurality of light emitters are arranged in a plurality of straight lines, and

[0277] The light emitters among the plurality of light emitters in each of the plurality of straight lines are connected to a corresponding one of the plurality of wirings, and each of the plurality of wirings extends from the first electrode.

[0278] (10) The light-emitting element according to (9), wherein

[0279] A plurality of the wirings include a wiring extending from the first electrode terminal through the peripheral region to the central region and a wiring extending from the first electrode terminal to the peripheral region, and

[0280] the wiring extending to the central region and the wiring extending to the peripheral region exhibit different resistances.

[0281] (11) The light-emitting element according to (10), wherein,

[0282] the wiring extending to the peripheral region has a larger cross-sectional area than the wiring extending to the central region.

[0283] (12) The light-emitting element according to any one of (5) to (11), wherein,

[0284] the first electrode included in one of the plurality of light emitters exhibits a contact resistance different from the contact resistance of the first electrode included in the other light emitter among the plurality of light emitters.

[0285] (13) The light-emitting element according to any one of (5) to (12), wherein,

[0286] each of the plurality of light emitters includes:

[0287] a first DBR layer electrically connected to the first electrode,

[0288] a second DBR layer electrically connected to the second electrode,

[0289] a current limiting layer disposed between the first DBR layer and the second DBR layer, and

[0290] an active layer disposed between the first DBR layer and the second DBR layer and emitting light due to the current limited by the current limiting layer,

[0291] each of the plurality of light emitters has a mesa structure in which, using a separation groove, at least the first DBR layer, the current limiting layer, and the active layer of the light emitter among the plurality of light emitters are spaced apart from at least the first DBR layer, the current limiting layer, and the active layer of an adjacent light emitter among the plurality of light emitters, and

[0292] the separation groove provided around one of the plurality of light emitters has a depth different from the depth of the separation groove provided around the other light emitter among the plurality of light emitters.

[0293] (14) A light-emitting element, comprising:

[0294] A plurality of light emitters arranged one-dimensionally or two-dimensionally in a direction perpendicular to an optical axis corresponding to light emitted from each of the plurality of light emitters, each of the plurality of light emitters being a vertical-cavity surface-emitting laser element, each of the plurality of light emitters including a first electrode and a second electrode, and each of the plurality of light emitters emitting light due to a current flowing from the first electrode to the second electrode;

[0295] A first electrode terminal electrically connected to the first electrode; and

[0296] A second electrode terminal electrically connected to the second electrode, wherein,

[0297] One of the plurality of light emitters has a light extraction efficiency different from that of another one of the plurality of light emitters.

[0298] (15) The light-emitting element according to (14), wherein,

[0299] When viewed from a direction extending parallel to the optical axis, the light-emitting element has a central region and a peripheral region, the central region including light emitters in an inner portion of the plurality of light emitters, the peripheral portion including light emitters in an outer peripheral portion of the plurality of light emitters, and

[0300] The light emitters included in the plurality of light emitters and in the central region have a lower light extraction efficiency than the light emitters included in the plurality of light emitters and in the peripheral region.

[0301] (16) The light-emitting element according to (14) or (15), wherein,

[0302] A surface coating is formed on a light-emitting surface of each of the plurality of light emitters, and

[0303] The surface coating of one of the plurality of light emitters has a thickness different from that of the surface coating of another one of the plurality of light emitters.

[0304] (17) The light-emitting element according to any one of (14) to (16), wherein,

[0305] A surface coating including a first region and a second region is provided on a light-emitting surface of each of the plurality of light emitters, the second region having optical properties different from those of the first region, and

[0306] The position of the boundary between the first region and the second region in one of the plurality of light emitters is different from the position of the boundary between the first region and the second region in the other of the plurality of light emitters.

[0307] (18) The light-emitting element according to any one of (14) to (17), wherein,

[0308] Each of the plurality of light emitters includes:

[0309] A first DBR layer electrically connected to the first electrode,

[0310] A second DBR layer electrically connected to the second electrode,

[0311] A current limiting layer disposed between the first DBR layer and the second DBR layer, and

[0312] An active layer disposed between the first DBR layer and the second DBR layer, and emitting light due to the current limited by the current limiting layer, and

[0313] The reflectivity of the first DBR layer of one of the plurality of light emitters and the reflectivity of the second DBR layer of one of the plurality of light emitters are respectively different from the reflectivity of the first DBR layer of the other of the plurality of light emitters and the reflectivity of the second DBR layer of the other of the plurality of light emitters.

[0314] (19) The light-emitting element according to (2) or (15), wherein,

[0315] The distribution of the light emission intensity of the plurality of light emitters from the central region to the peripheral region has a shape represented by cos n θ.

[0316] (20) A distance measuring device, comprising:

[0317] A light-emitting unit including a light-emitting element, the light-emitting element including:

[0318] A plurality of light emitters arranged one-dimensionally or two-dimensionally in a direction perpendicular to the optical axis corresponding to the light emitted from each of the plurality of light emitters, each of the plurality of light emitters being a vertical cavity surface emitting laser element, each of the plurality of light emitters including a first electrode and a second electrode, and each of the plurality of light emitters emitting light due to the current flowing from the first electrode to the second electrode,

[0319] A first electrode terminal, electrically connected to the first electrode, and

[0320] A second electrode terminal, electrically connected to the second electrode, wherein,

[0321] A current path from the first electrode terminal, through one of the plurality of light emitters, to the second electrode terminal exhibits a resistance different from that of a current path from the first electrode terminal, through another of the plurality of light emitters, to the second electrode terminal;

[0322] A light receiving unit that detects reflected light that is light emitted from the light emitting unit; and

[0323] A ranging calculation unit that calculates the distance to a measurement target based on the result of detection performed by the light receiving unit.

[0324] List of reference symbols

[0325] 100 Ranging device

[0326] 101 Light emitting unit

[0327] 102 Light emission controller

[0328] 103 Light receiving unit

[0329] 104 Ranging calculation unit

[0330] 111 Light emitting element

[0331] 111a Light emitter

[0332] 111a1 First light emitter

[0333] 111a2 Second light emitter

[0334] 111a3 Third light emitter

[0335] 122 n-type DBR layer

[0336] 123 n-type cladding layer

[0337] 124 Active layer

[0338] 125 p-type cladding layer

[0339] 126 Current limiting layer

[0340] 126a Limiting region

[0341] 126b Injection region

[0342] 127 p-type DBR layer

[0343] 128 Contact layer

[0344] 129 Insulating layer

[0345] 130 p-type electrode

[0346] 131 n-type electrode

[0347] 135 Surface coating

[0348] 136 Surface coating

[0349] 137 Surface coating

[0350] 141 Anode

[0351] 151 Cathode.

Claims

1. A light-emitting element, comprising: A plurality of optical transmitters are arranged one-dimensionally or two-dimensionally in a direction perpendicular to an optical axis corresponding to light emitted from each of the plurality of optical transmitters. Each of the plurality of optical transmitters is a vertical cavity surface emitting laser element. Each of the plurality of optical transmitters includes a first electrode and a second electrode, and each of the plurality of optical transmitters emits light due to a current flowing from the first electrode to the second electrode; A first electrode terminal is electrically connected to the first electrode; and a second electrode terminal is electrically connected to the second electrode, wherein a current path from the first electrode terminal through one of the plurality of optical transmitters to the second electrode terminal exhibits a resistance different from a resistance of a current path from the first electrode terminal through another of the plurality of optical transmitters to the second electrode terminal, wherein, when viewed in a direction extending parallel to the optical axis, the light emitting element has a central region and a peripheral region. The central region includes optical transmitters in an inner portion of the plurality of optical transmitters, and the peripheral region includes optical transmitters in an outer peripheral portion of the plurality of optical transmitters, and a wiring connecting the first electrode terminal and the optical transmitter included in the plurality of optical transmitters and in the central region exhibits a higher resistance than the wiring connecting the first electrode terminal and the optical transmitter included in the plurality of optical transmitters and in the peripheral region, and wherein the plurality of optical transmitters are arranged in a plurality of straight lines, and optical transmitters in each of the plurality of optical transmitters in each of the plurality of straight lines are connected to a corresponding one of the plurality of wirings, and each of the plurality of wirings extends from the first electrode.

2. The light-emitting element according to claim 1, wherein, When viewed in a direction extending parallel to the optical axis, the light emitting element has a central region and a peripheral region. The central region includes optical transmitters in an inner portion of the plurality of optical transmitters, and the peripheral region includes optical transmitters in an outer peripheral portion of the plurality of optical transmitters, and a current path through the optical transmitter included in the plurality of optical transmitters and in the central region exhibits a higher resistance than a current path through the optical transmitter included in the plurality of optical transmitters and in the peripheral region.

3. The light-emitting element according to claim 1, wherein, Each of the plurality of optical transmitters includes: a first distributed Bragg reflector (DBR) layer electrically connected to the first electrode, a second DBR layer electrically connected to the second electrode, a current confinement layer disposed between the first DBR layer and the second DBR layer, and an active layer disposed between the first DBR layer and the second DBR layer and emitting light due to a current confined by the current confinement layer, the current confinement layer has a confinement region and an injection region, and the injection region has a higher conductivity than the confinement region, and a resistance of a current path of the optical transmitters in the plurality of optical transmitters varies according to a size of an aperture diameter which is a diameter of the injection region.

4. The light-emitting element according to claim 3, wherein, Each of the plurality of light emitters has a mesa structure in which at least the first DBR layer, the current confinement layer, and the active layer of the light emitter among the plurality of light emitters are spaced apart from at least the first DBR layer, the current confinement layer, and the active layer of an adjacent light emitter among the plurality of light emitters, and the size of the aperture diameter varies according to the size of the mesa diameter.

5. The light-emitting element according to claim 1, wherein, The wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and located in the central region is longer than the wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and located in the peripheral region.

6. The light-emitting element according to claim 1, wherein, The plurality of wirings include a wiring extending from the first electrode terminal through the peripheral region to the central region and a wiring extending from the first electrode terminal to the peripheral region, and the wiring extending to the central region and the wiring extending to the peripheral region exhibit different resistances.

7. The light-emitting element according to claim 6, wherein, The wiring extending to the peripheral region has a larger cross-sectional area than the wiring extending to the central region.

8. The light-emitting element according to claim 1, wherein, The first electrode in one light emitter included in the plurality of light emitters exhibits a contact resistance different from the contact resistance of the first electrode in another light emitter included in the plurality of light emitters.

9. The light-emitting element according to claim 1, wherein, Each of the plurality of light emitters includes: a first distributed Bragg reflector (DBR) layer electrically connected to the first electrode, a second DBR layer electrically connected to the second electrode, a current confinement layer disposed between the first DBR layer and the second DBR layer, and an active layer disposed between the first DBR layer and the second DBR layer and emitting light due to the current confined by the current confinement layer, each of the plurality of light emitters has a mesa structure in which at least the first DBR layer, the current confinement layer, and the active layer of the light emitter among the plurality of light emitters are spaced apart from at least the first DBR layer, the current confinement layer, and the active layer of an adjacent light emitter among the plurality of light emitters by using isolation grooves, and the isolation groove provided around one light emitter among the plurality of light emitters has a depth different from the depth of the isolation groove provided around another light emitter among the plurality of light emitters.

10. The light-emitting element according to claim 2, wherein, The distribution of the luminous intensity of the plurality of light emitters from the central region to the peripheral region has a shape represented by cos n θ.

11. A light-emitting element, comprising: A plurality of light emitters are arranged one-dimensionally or two-dimensionally in a direction perpendicular to an optical axis corresponding to light emitted from each of the plurality of light emitters. Each of the plurality of light emitters is a vertical cavity surface emitting laser element. Each of the plurality of light emitters includes a first electrode and a second electrode. Each of the plurality of light emitters emits light due to a current flowing from the first electrode to the second electrode; a first electrode terminal electrically connected to the first electrode; and a second electrode terminal electrically connected to the second electrode, where One of the plurality of light emitters has a light extraction efficiency different from that of another light emitter among the plurality of light emitters. A surface coating is formed on a light-emitting surface of each of the plurality of light emitters, and the surface coating of the one light emitter among the plurality of light emitters has a thickness different from that of the surface coating of the another light emitter among the plurality of light emitters.

12. The light-emitting element according to claim 11, wherein, When viewed in a direction extending parallel to the optical axis, the light-emitting element has a central region and a peripheral region. The central region includes light emitters in an inner portion of the plurality of light emitters, and the peripheral region includes light emitters in an outer peripheral portion of the plurality of light emitters. And the light emitters included in the plurality of light emitters and in the central region have a lower light extraction efficiency than the light emitters included in the plurality of light emitters and in the peripheral region.

13. The light-emitting element according to claim 11, wherein, A surface coating including a first region and a second region is provided on a light-emitting surface of each of the plurality of light emitters. The second region has optical characteristics different from those of the first region, and the position of a boundary between the first region and the second region in the one light emitter among the plurality of light emitters is different from the position of the boundary between the first region and the second region in the another light emitter among the plurality of light emitters.

14. The light-emitting element according to claim 11, wherein, Each of the plurality of light emitters includes: a first distributed Bragg reflector (DBR) layer electrically connected to the first electrode, a second DBR layer electrically connected to the second electrode, a current limiting layer disposed between the first DBR layer and the second DBR layer, and an active layer disposed between the first DBR layer and the second DBR layer and emitting light due to current limited by the current limiting layer. And the reflectivity of the first DBR layer of the one light emitter among the plurality of light emitters and the reflectivity of the second DBR layer of the one light emitter among the plurality of light emitters are respectively different from the reflectivity of the first DBR layer of the another light emitter among the plurality of light emitters and the reflectivity of the second DBR layer of the another light emitter among the plurality of light emitters.

15. The light-emitting element according to claim 12, wherein, The distribution of the luminous intensity of the plurality of light emitters from the central region to the peripheral region has a shape represented by cos n θ.

16. A ranging device, comprising: A light-emitting unit including a light-emitting element, the light-emitting element including: a plurality of light emitters arranged one-dimensionally or two-dimensionally in a direction perpendicular to an optical axis corresponding to light emitted from each of the plurality of light emitters. Each of the plurality of light emitters is a vertical cavity surface emitting laser element. Each of the plurality of light emitters includes a first electrode and a second electrode, and each of the plurality of light emitters emits light due to current flowing from the first electrode to the second electrode. a first electrode terminal electrically connected to the first electrode, and a second electrode terminal electrically connected to the second electrode, where The current path from the first electrode terminal, through one of the plurality of light emitters, to the second electrode terminal exhibits a resistance different from the resistance of the current path from the first electrode terminal, through another of the plurality of light emitters, to the second electrode terminal. Wherein, when viewed from a direction extending parallel to the optical axis, the light emitting element has a central region and a peripheral region, the central region includes light emitters in an inner portion of the plurality of light emitters, the peripheral region includes light emitters in an outer peripheral portion of the plurality of light emitters, and the wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and in the central region exhibits a higher resistance than the wiring connecting the first electrode terminal to the light emitter included in the plurality of light emitters and in the peripheral region and wherein, the plurality of light emitters are arranged in a plurality of straight lines, and the light emitters in each of the plurality of light emitters in each of the plurality of straight lines are connected to a corresponding one of the plurality of wirings, and each of the plurality of wirings extends from the first electrode; a light receiving unit that detects reflected light that is light emitted from the light emitting unit; and a distance measurement calculation unit that calculates the distance to the measurement target based on the result of the detection performed by the light receiving unit.

Images