Optical device and distance measurement device

Abstract

[Problem] To provide an optical device and a distance measurement device capable of appropriately detecting the emission timing of oscillating light. [Solution] An optical device according to the present disclosure comprises: a light-emitting element that emits light of a second wavelength, and that comprises a semiconductor part that is included in a first resonator that resonates light of a first wavelength and oscillates the light of the first wavelength, a solid-state laser medium, and a saturable absorber; a solid-state laser medium included in the first resonator and included in a second resonator that resonates light of a second wavelength and oscillates light of the second wavelength, and a saturable absorber included in the second resonator; a detector for detecting light of the first wavelength or a driving current of the light emitting element; and an emission timing detection unit for detecting the emission timing of the light of the second wavelength on the basis of the detection result of the light of the first wavelength or the driving current of the light-emitting element obtained by the detector.

Description

Technical Field

[0001] The present disclosure relates to optical devices and distance measuring devices. Background Art

[0002] The technology of short pulse lasers is used in the fields of distance measurement, etc. For example, Q-switched solid-state laser elements can achieve high peak powers exceeding kW (kilowatts) with a relatively simple configuration, and are therefore used as light sources for distance measurement devices of direct time-of-flight (dToF) systems.

[0003] Reference List

[0004] Patent Literature

[0005] Patent document 1: WO 2021 / 106757.

[0006] Patent document 2: JP 2000-269598 A.

[0007] Patent document 3: WO 2021 / 051814. Summary of the invention

[0008] Technical issues

[0009] When a Q-switched laser element is used in dToF, in order to determine the emission time of the oscillating light, it is necessary to extract a portion of the oscillating light and detect it using a photodetector. For example, in the case of a Q-switched laser element in which the wavelength of the excitation light is 940nm and the wavelength of the oscillating light is 1030nm in dToF, in order to detect the emission time of the oscillating light with high sensitivity, an expensive photodetector such as an InGaAs photodetector with a sensitivity level of 1030nm is required. In addition, in order to detect the emission time of the oscillating light, a reflector that reflects the oscillating light and a photodetector that detects the oscillating light are required, and therefore, there is a problem that it is difficult to reduce the size of the distance measuring device and the impact resistance of the distance measuring device is weak. In addition, in the case where the Q-switched laser element is configured as an array, there is a problem that it is difficult to arrange the reflector and the photodetector, and the emission time of the oscillating light of each pixel cannot be accurately detected due to light leakage between pixels.

[0010] In order to reduce the size of the distance measuring device, a vertical cavity surface emitting laser (VCSEL) element with a wavelength of 1030 nm may be considered as a light source. However, in this case, there is a problem that high power cannot be obtained as in the case of a Q-switched laser element.

[0011] The present disclosure provides an optical device and a distance measuring device capable of appropriately detecting emission timing of oscillation light.

[0012] Solution to the problem

[0013] An optical device according to a first aspect of the present disclosure includes: a light emitting element including a semiconductor portion, a solid-state laser medium, and a saturable absorber and emitting light of a second wavelength, the semiconductor portion being included in a first resonator that resonates light of a first wavelength and oscillates the light of the first wavelength, the solid-state laser medium being included in the first resonator and in a second resonator that resonates light of a second wavelength and oscillates the light of the second wavelength, and the saturable absorber being included in the second resonator; a detector that detects light of the first wavelength or a driving current of the light emitting element; and an emission timing detection unit that detects the emission timing of the light of the second wavelength based on a detection result of the light of the first wavelength or the driving current of the light emitting element obtained using the detector. Accordingly, for example, by using the detection result of the light of the first wavelength (excitation light) or the driving current of the light emitting element, the emission timing of the light of the second wavelength (oscillation light) can be appropriately detected.

[0014] In addition, in the first aspect, the intensity of the light of the first wavelength or the value of the driving current of the light emitting element may be changed according to the emission timing of the light of the second wavelength. Accordingly, for example, by using the intensity of the light of the first wavelength or the value of the driving current of the light emitting element to be changed according to the emission timing of the light of the second wavelength, the emission timing of the light of the second wavelength can be appropriately detected.

[0015] In addition, the optical device according to the first aspect may further include a distance measurement unit that performs distance measurement based on the detection result of the emission timing of the light of the second wavelength acquired using the emission timing detection unit. Accordingly, for example, appropriate distance measurement can be performed based on appropriate detection results of the emission timing.

[0016] In addition, the optical device according to the first aspect may further include a light receiving element that receives reflected light of the light of the second wavelength, wherein the distance measurement unit can perform distance measurement based on the detection result of the emission timing of the light of the second wavelength acquired using the emission timing detection unit and the light reception result of the reflected light acquired using the light receiving element. Accordingly, for example, appropriate distance measurement can be performed from the light reception result based on an appropriate detection result of the emission timing.

[0017] In addition, the optical device according to the first aspect may further include a light reception timing detection unit that detects the light reception timing of the reflected light based on the light reception result of the reflected light acquired using the light receiving element, wherein the distance measurement unit can perform distance measurement based on the detection result of the emission timing of the light of the second wavelength acquired using the emission timing detection unit and the detection result of the light reception timing of the reflected light acquired using the light reception timing detection unit. Accordingly, for example, appropriate distance measurement can be performed based on appropriate detection results of the emission and light reception timings.

[0018] Furthermore, the optical device according to the first aspect may further include a difference detection unit that detects a difference between the emission timing of the light of the second wavelength and the light reception timing of the reflected light, wherein the distance measurement unit may perform distance measurement based on the difference detected using the difference detection unit. Accordingly, for example, by appropriately detecting the difference between the emission timing and the light reception timing, appropriate distance measurement may be performed based on the difference.

[0019] In addition, in the first aspect, the optical device may be a distance measuring device that performs distance measurement based on the detection result of the emission timing of the light of the second wavelength acquired using the emission timing detection unit. Accordingly, for example, a distance measuring device that performs appropriate distance measurement can be provided.

[0020] In addition, in the first aspect, the optical device may be a light emitting device that emits light of the second wavelength and is included in the distance measuring device together with a light receiving device that receives light of the second wavelength. Accordingly, for example, a light emitting device capable of achieving appropriate distance measurement can be provided.

[0021] Furthermore, in this first aspect, the light emitting element may include: a first reflection layer located in the semiconductor portion and reflecting light of a first wavelength; a second reflection layer located on the first surface of the solid-state laser medium and reflecting light of a second wavelength; a third reflection layer located on the second surface of the solid-state laser medium and reflecting light of the first wavelength; a fourth reflection layer located on the surface of the saturable absorber and reflecting light of the second wavelength; and a fifth reflection layer located in the semiconductor portion, located on the solid-state laser medium side of the first reflection layer, and reflecting a portion of the light of the first wavelength. Accordingly, for example, the first resonator and the second resonator can be realized using such reflection layers.

[0022] Furthermore, in the first aspect, the detector may be arranged on the second resonator side of the light emitting element. Accordingly, for example, the substrate may be arranged on one side of the light emitting element, and the detector may be arranged on the other side of the light emitting element.

[0023] Furthermore, in this first aspect, the detector may be arranged on the first resonator side of the light emitting element. Accordingly, for example, a substrate may be arranged on one side of the light emitting element, and the detector may be arranged in or on the substrate.

[0024] Furthermore, in the first aspect, the detector may be installed in the light emitting element. Accordingly, for example, a structure in which the light emitting element and the detector are integrated together can be realized.

[0025] In addition, in the first aspect, the light emitting element may be provided on the first surface side of the substrate, and the detector may be provided on the first surface side of the substrate and in a layer provided between the substrate and the light emitting element. Accordingly, for example, the detector may be arranged near the light emitting element.

[0026] In addition, in the first aspect, the light emitting element may be provided on the first surface side of the substrate, and the detector may be provided in a layer provided on the second surface side of the substrate. Accordingly, for example, the light emitting element and the detector may be provided on different surfaces of the substrate.

[0027] Furthermore, in the first aspect, the optical device may include a plurality of light emitting elements arranged in an array as the light emitting element. Accordingly, for example, distance measurement can be performed using an image.

[0028] In addition, in the first aspect, the optical device may further include a plurality of detectors arranged in an array in the same layer as the detectors. According to this, for example, the detectors corresponding to the light emitting elements on a one-to-one basis can be simply formed.

[0029] In addition, the optical device according to the first aspect may further include a driving unit that drives the plurality of light emitting elements, and the driving unit may sequentially excite light from the plurality of light emitting elements by scanning the plurality of light emitting elements. Accordingly, for example, the configuration of the driving unit may be simplified.

[0030] In addition, the optical device according to the first aspect may further include a driving unit that drives a plurality of light emitting elements, and the driving unit may simultaneously excite light from a plurality of light emitting elements by driving the plurality of light emitting elements simultaneously. Accordingly, for example, such light emitting elements may be driven in a short time.

[0031] The distance measuring device according to the second aspect of the present disclosure includes: a light emitting element including a semiconductor portion, a solid-state laser medium, and a saturable absorber, and emitting light of a second wavelength, the semiconductor portion being included in a first resonator that resonates light of a first wavelength and oscillates the light of the first wavelength, the solid-state laser medium being included in the first resonator and a second resonator that resonates light of a second wavelength and oscillates the light of the second wavelength, the saturable absorber being included in the second resonator; a detector that detects light of the first wavelength or a driving current of the light emitting element; a light receiving element that receives reflected light of the light of the second wavelength; and a distance measuring unit that performs distance measurement based on a detection result of the light of the first wavelength or the driving current of the light emitting element obtained using the detector and a light reception result of the reflected light obtained using the light receiving element. Accordingly, for example, by using the detection result of the reflected light of the light of the first wavelength (excitation light) or the driving current of the light emitting element, appropriate distance measurement can be performed by appropriately detecting the emission timing of the light of the second wavelength (oscillation light).

[0032] In addition, the distance measuring device according to the second aspect further includes: an emission timing detection unit that detects the emission timing of the light of the second wavelength based on the detection result of the light of the first wavelength or the driving current of the light emitting element obtained using the detector, and the distance measuring unit can perform distance measurement based on the detection result of the emission timing of the light of the second wavelength obtained using the emission timing detection unit and the light reception result of the reflected light obtained using the light receiving element. Accordingly, for example, appropriate distance measurement can be performed by appropriately detecting the emission timing of the light of the second wavelength. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 : is a schematic diagram showing the structure of the distance measurement device 100 according to the first embodiment.

[0034] Figure 2 is a cross-sectional view for describing the structure of the light emitting element 1 according to the first embodiment.

[0035] Figure 3 : is a block diagram showing the structure of the distance measurement device 100 according to the first embodiment.

[0036] Figure 4 : is a block diagram showing the structure of a distance measurement device 100 of a modified example of the first embodiment.

[0037] Figure 5 is a graph for describing the operation of the light emitting element 1 according to the first embodiment.

[0038] Figure 6 is a cross-sectional view showing the structure of a light emitting element 1 according to a modified example of the first embodiment.

[0039] Figure 7 is a cross-sectional view showing the structure of a light emitting element 1 according to a modified example of the first embodiment.

[0040] Figure 8 : is a schematic diagram showing the structure of a distance measurement device 100 of a modified example of the first embodiment.

[0041] Fig. 9 : is a block diagram showing the structure of a distance measurement device 100 of a modified example of the first embodiment.

[0042] Fig.10 is a perspective view showing the structure of a light emitting device 101 according to a second embodiment.

[0043] Fig.11 : is a perspective view showing the structure of a light emitting device 101 of a comparative example of the second embodiment.

[0044] Fig.12is a cross-sectional view showing the structure of a light emitting device 101 of a modified example of the second embodiment.

[0045] Fig.13 : is a schematic diagram showing the structure of a distance measurement device 100 according to the second embodiment.

[0046] Fig.14 : is a block diagram showing the structure of a distance measurement device 100 according to the second embodiment.

[0047] Fig.15 : is a block diagram showing the structure of a distance measurement device 100 of a modified example of the second embodiment.

[0048] Fig.16 : is a block diagram showing the structure of a distance measurement device 100 of a modified example of the second embodiment.

[0049] Fig.17 is a block diagram showing the structure of a distance measurement device 100 according to the third embodiment.

[0050] Fig.18 : is a block diagram showing the structure of a distance measurement device 100 of a modified example of the third embodiment. DETAILED DESCRIPTION

[0051] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0052] (First Embodiment)

[0053] Figure 1 : is a schematic diagram showing the structure of the distance measurement device 100 according to the first embodiment.

[0054] like Figure 1 As shown, the distance measuring device 100 includes a light emitting device 101 and a light receiving device 102. The distance measuring device 100 emits light emitted from the light emitting device 101 onto an object S, and receives light reflected on the object S using the light receiving device 102. The distance measuring device 100 performs distance measurement on the object S, in other words, measures the distance between the object S and the distance measuring device 100.

[0055] The light emitting device 101 includes a light emitting element 1, a half mirror 2, and a photodiode (PD) 3. The light receiving device 102 includes a light receiving element 4 and an arithmetic operation circuit 5. The photodiode 3 and the arithmetic operation circuit 5 are respective examples of a detector and a distance measuring unit of the present disclosure.

[0056] The light emitting element 1 includes a semiconductor portion 11, a solid-state laser medium 12, and a saturable absorber (Q switch) 13. The semiconductor portion 11 and the solid-state laser medium 12 form a resonator 21, and the solid-state laser medium 12 and the saturable absorber 13 form a resonator 22. The resonator 21 and the resonator 22 are respective examples of a first resonator and a second resonator of the present disclosure.

[0057] The semiconductor portion 11 oscillates light having a predetermined wavelength. This light is used to excite the solid-state laser medium 12 and is therefore referred to as excitation light. The wavelength of the excitation light is, for example, 940 nm. This wavelength is an example of the first wavelength of the present disclosure. The excitation light is also referred to as excitation laser.

[0058] The solid-state laser medium 12 is excited by the excitation light, thereby oscillating light having a predetermined wavelength different from the wavelength of the excitation light. This light corresponds to the oscillation light as a Q-switched solid-state laser element, and is therefore referred to as oscillation light. The wavelength of the oscillation light is, for example, 1030 nm. This wavelength is an example of the second wavelength of the present disclosure. The oscillation light is also referred to as oscillation laser light.

[0059] The saturable absorber 13 has a function of absorbing a part of the light generated in the semiconductor portion 11 and the solid-state laser medium 12 and a function of releasing a part of the light generated in the semiconductor portion 11 and the solid-state laser medium 12 to the outside. For example, the oscillation light generated in the solid-state laser medium 12 passes through the saturable absorber 13, and is released to the outside from the saturable absorber 13. This light becomes the emission light emitted from the light emitting element 1.

[0060] The resonator 21 includes a semiconductor portion 11 and a solid-state laser medium 12, and resonates light having a wavelength of 940 nm. The resonator 22 includes a solid-state laser medium 12 and a saturable absorber 13, and resonates light having a wavelength of 1030 nm. Therefore, the light-emitting element 1 according to the present embodiment can generate light having a wavelength of 940 nm as excitation light, and generate light having a wavelength of 1030 nm as oscillation light. In addition, the resonant wavelength of the resonator 21 may be a wavelength other than 940 nm, and the resonant wavelength of the resonator 22 may be a wavelength other than 1030 nm. Such resonators 21 and resonators 22 share the solid-state laser medium 12 and therefore overlap each other in the region of the solid-state laser medium 12.

[0061] Figure 1 Light L emitted from the light emitting element 1 is shown. Although the light L mainly includes light L2 corresponding to oscillation light, the light L also includes light L1 corresponding to excitation light. The wavelength of the light L1 is, for example, 940 nm. The wavelength of the light L2 is, for example, 1030 nm. Other details of the light emitting element 1 will be described below.

[0062] The half mirror 2 is arranged at a position where the light L is incident and separates the light L into the light L1 and the light L2. The light L1 is supplied to the photodiode 3. The light L2 is emitted from the light emitting device 101 and becomes the emission light emitted to the object S. Figure 1 In the embodiment, the light L2 is emitted to the object S, and the light L2 ′ which is the reflected light of the light L2 is guided from the object S to the light receiving device 102 .

[0063] The photodiode 3 is arranged at a position where the light L1 is incident, detects the light L1, and outputs a signal indicating the detection result of the light L1. For example, the photodiode 3 receives the light L1, performs photoelectric conversion, and outputs a signal charge generated by the photoelectric conversion. The signal output from the photodiode 3 is input to the arithmetic operation circuit 5. The signal may be a current signal obtained from the above-mentioned signal charge or a voltage signal obtained from the above-mentioned signal charge.

[0064] The light receiving element 4 receives the light L2' from the object S and outputs a signal indicating the light reception result of the light L2'. The light receiving element 4 is, for example, a photodiode and outputs a signal obtained by photoelectric conversion of the light L2'. The signal output from the light receiving element 4 is input to the arithmetic operation circuit 5.

[0065] The arithmetic operation circuit 5 performs various arithmetic operations related to distance measurement and other information processing. The arithmetic operation circuit 5 performs distance measurement on the object S based on the above-mentioned signal input from the photodiode 3 and the above-mentioned signal input from the light receiving element 4, for example. Other details of the arithmetic operation circuit 5 will be described below.

[0066] Figure 2 is a cross-sectional view for describing the structure of the light emitting element 1 according to the first embodiment.

[0067] As described above, the light emitting element 1 includes the semiconductor portion 11, the solid-state laser medium 12, and the saturable absorber 13. In the light emitting element 1 according to the present embodiment, although the semiconductor portion 11 and the solid-state laser medium 12 are in contact with each other, and the solid-state laser medium 12 and the saturable absorber 13 are in contact with each other, Figure 2 In order to facilitate understanding of the description, the semiconductor portion 11 and the solid-state laser medium 12 are drawn to be separated from each other, and the solid-state laser medium 12 and the saturable absorber 13 are drawn to be separated from each other. The semiconductor portion 11 and the solid-state laser medium 12 form a resonator 21, and the solid-state laser medium 12 and the saturable absorber 13 form a resonator 22.

[0068] Figure 2 An X-axis, a Y-axis, and a Z-axis perpendicular to each other are shown, the X-direction and the Y-direction correspond to the horizontal direction, and the Z-direction corresponds to the vertical direction. Figure 2In FIG. 1 , although the semiconductor portion 11 , the solid-state laser medium 12 , and the saturable absorber 13 are arranged in sequence in the X direction, they may be arranged in sequence in any other direction.

[0069] Figure 2 Surface A1 of the semiconductor portion 11 in the -X direction, surface B1 of the semiconductor portion 11 in the +X direction, surface A2 of the solid-state laser medium 12 in the -X direction, surface B2 of the solid-state laser medium 12 in the +X direction, surface A3 of the saturable absorber 13 in the -X direction, and surface B3 of the saturable absorber 13 in the +X direction are shown. In the light emitting element 1 according to the present embodiment, surface B1 of the semiconductor portion 11 is in contact with surface A2 of the solid-state laser medium 12, and surface B2 of the solid-state laser medium 12 is in contact with surface A3 of the saturable absorber 13.

[0070] The semiconductor portion 11 includes an n-distributed Bragg reflector (DBR) layer 31, a cladding layer 32, an active layer 33, a cladding layer 34, an oxide layer 35, and a p-DBR layer 36 in this order. Figure 2 In the embodiment, the n-DBR layer 31 is located on the surface A1 side, and the p-DBR layer 36 is located on the surface B1 side. In addition, as will be described below, the semiconductor layer 11 may include the n-DBR layer 31 on the surface B1 side, and the p-DBR layer 36 on the surface A1 side.

[0071] The n-DBR layer 31 includes a plurality of low refractive index layers and a plurality of high refractive index layers alternately stacked. These low refractive index layers and high refractive index layers are, for example, Al z1 Ga 1-z1 As layer and Al z2 Ga 1-z2 As layer. Here, Al, Ga and As represent aluminum, gallium and arsenic, respectively. In addition, z1 and z2 are real numbers satisfying "0≤z1<z2≤1", and z2 is preferably less than 1. The n-DBR layer 31 also contains an n-type dopant (eg, silicon).

[0072] The cladding layer 32 is, for example, a non-doped AlGaAs layer.

[0073] The active layer 33 has a quantum well structure, and more specifically, includes a plurality of quantum well layers and a plurality of barrier layers alternately stacked to have compressive strain. These quantum well layers and barrier layers are, for example, Al x1 In y1 Ga 1-x1-y1 As layer and Al x2 In y2 Ga 1-x2-y2As layer. Here, In represents indium. In addition, x1, y1, x2, and y2 are real numbers satisfying "0≤x1, y1, x2, y2≤1", "0≤x1+y1≤1", and "0≤x2+y2≤1". The active layer 33 may have a multi-junction structure through a tunnel junction.

[0074] The cladding layer 34 is, for example, a non-doped AlGaAs layer.

[0075] The oxide layer 35 includes, for example, an AlAs layer and an Al2O3 layer obtained by oxidizing the AlAs layer (here, O represents oxygen). For example, oxidation from the AlAs layer to the Al2O3 layer is performed using water vapor. By using the oxide layer 35, electrical and optical confinement can be performed. In addition, the oxide layer 35 according to the present embodiment has a cylindrical opening portion (not shown) passing through the oxide layer 35 at the center portion of the oxide layer 35 in a plan view.

[0076] The p-DBR layer 36 includes a plurality of low refractive index layers and a plurality of high refractive index layers alternately stacked. These low refractive index layers and high refractive index layers are, for example, Al z3 Ga 1-z3 As layer and Al z4 Ga 1-z4 As layer. Here, z3 and z4 are real numbers satisfying "0≤z3<z4≤1", and z4 is preferably smaller than 1. The p-DBR layer 36 also contains a p-type dopant (eg, carbon).

[0077] The semiconductor portion 11 further includes an n-contact layer (not shown) in the -X direction of the n-DBR layer 31 and a p-contact layer (not shown) in the +X direction of the p-DBR layer 36. The n-contact layer is, for example, a GaAs layer containing an n-type dopant, and is in contact with an n-metal layer (not shown) serving as a metal electrode. The p-contact layer is, for example, a GaAs layer containing a p-type dopant, and is in contact with a p-metal layer (not shown) serving as a metal electrode.

[0078] The solid-state laser medium 12 is, for example, a Yb:YAG crystal, i.e., a YAG (yttrium aluminum garnet) crystal doped with Yb (yttrium). In this case, the resonance wavelength of the resonator 21 is 940 nm, and the resonance wavelength of the resonator 22 is 1030 nm. The solid-state laser medium 12 can be formed as any one of Nd:YAG, Nd:YVO4, Nd:YLF, Nd:glass, Yb:YAG, Yb:YLF, Yb:FAP, Yb:SFAP, Yb:YVO, Yb:glass, Yb:KYW, Yb:BCBF, Yb:YCOB, Yb:GdCOB, and YB:YAB. In addition, the solid-state laser medium 12 can be a four-level laser medium or a three-level laser medium.

[0079] The saturable absorber 13 is, for example, a Cr:YAG crystal, i.e., a YAG crystal doped with Cr (chromium). The saturable absorber 13 is also called a Q switch. The Q switch is a material that exhibits saturable absorption characteristics for the light intensity of the laser beam passing through the Q switch. The saturable absorber 13 may also be a V:YAG crystal, i.e., a YAG crystal doped with V (vanadium). The saturable absorber 13 may also be formed of a material that can realize an active Q switch element.

[0080] In the present embodiment, the semiconductor portion 11 oscillates the excitation light by surface emission from the active layer 33, and excites the solid-state laser medium 12 using the excitation light. The solid-state laser medium 12 oscillates the oscillation light by being excited using the excitation light. The oscillation light passes through the saturable absorber 13 and is released to the outside from the saturable absorber 13. As a result, light is emitted from the light emitting element 1.

[0081] like Figure 2 As shown, the light emitting element 1 further includes reflective layers R1, R2, R3, R4 and R5. The reflective layers R1, R2, R3, R4 and R5 are corresponding examples of the first reflective layer, the second reflective layer, the third reflective layer, the fourth reflective layer and the fifth reflective layer of the present disclosure.

[0082] The reflective layer R1 is formed using the n-DBR layer 31 and is used as a high reflective layer for 940nm light. The reflective layer R3 is formed on the surface B2 of the solid-state laser medium 12 and is used as a high reflective layer for 940nm light. The surface B2 is an example of the second surface of the solid-state laser medium 12 of the present disclosure. The reflective layer R3 is configured as a long wave bandpass filter (LWPF), for example. The reflective layer R5 is formed using the p-DBR layer 36 and is used as a partial reflective layer with high reflectivity for 940nm light. For example, the reflectivity is about 95%. In this way, the reflective layers R1, R3 and R5 are able to reflect 940nm light. The resonator 21 according to the present embodiment is realized by such reflective layers R1, R3 and R5. The resonator 21 according to the present embodiment is configured as a resonator of a VCSEL, which is a semiconductor laser of a surface emitting laser type. Figure 2 The appearance of light (L1) of 940 nm generated between the reflective layer R1 and the reflective layer R3 is schematically shown.

[0083] The reflective layer R2 is formed on the surface A2 of the solid-state laser medium 12 and serves as a high reflective layer for light of 1030 nm. The surface A2 is an example of the first surface of the solid-state laser medium 12 of the present disclosure. The reflective layer R2 is configured as a short-wave bandpass filter (SWPF), for example. The reflective layer R4 is formed on the surface B3 of the saturable absorber 13 and serves as a partial reflective layer for light of 1030 nm. In this way, the reflective layers R2 and R4 are capable of reflecting light of 1030 nm. The resonator 22 according to the present embodiment is realized by such reflective layers R2 and R4. The resonator 22 according to the present embodiment is configured as a resonator of a Q-switched solid-state laser. Figure 2 The appearance of the light (L2) of 1030 nm generated between the reflective layer R2 and the reflective layer R4 is schematically shown.

[0084] In the present embodiment, light having a wavelength of 940 nm is used as excitation light for exciting the solid-state laser medium 12. For this reason, the reflective layer R3 according to the present embodiment is configured as a high reflective layer, and accordingly, the energy of the excitation light can be confined within the resonator 21. The resonator 21 according to the embodiment is configured as a coupled resonator (coupled cavity) including three reflective layers R1, R3, and R5. The reflective layer R5 is called an intermediate reflective layer and has a constant transmittance to the excitation light.

[0085] On the other hand, the reflective layer R4 is configured as a partial reflective layer. When the solid-state laser medium 12 is excited by the excitation light, the resonator 22 reaches Q-switched laser pulse oscillation. As a result, light with a wavelength of 1030 nm is generated as oscillated light. The oscillated light passes through the reflective layer R4 and is emitted as emission light of the light emitting element 1. In addition, the reflective layer R4 may be provided at a position other than the surface B3 of the saturable absorber 13 as long as the reflective layer is provided in the +X direction of the surface B3 of the saturable absorber 13.

[0086] In addition, the resonator 22 may include a wavelength conversion material for converting the wavelength of the oscillation light from 1030 nm to a value other than 1030 nm. The wavelength conversion material is, for example, a nonlinear optical crystal of LiNbO3, BBO, LBO, CLBO, BiBO, KTP, SLT, etc. The wavelength conversion material may also be a phase matching material similar to such a nonlinear optical crystal. In addition, the resonator 22 may include an optical filter, a polarizer, a diffraction grating, etc.

[0087] Here, an operation example of the light emitting element 1 according to the present embodiment will be described.

[0088] When current is injected from the electrode provided in the semiconductor portion 11 into the active layer 33, laser oscillation of oscillating excitation light occurs. As a result, the solid-state laser medium 12 is excited by the excitation light, and light is generated from the solid-state laser medium 12. However, since the resonator 22 includes the saturable absorber 13, immediately after the solid-state laser medium 12 is excited, the light (spontaneously emitted light) generated from the solid-state laser medium 12 is partially absorbed by the saturable absorber 13. Therefore, the oscillation threshold is not reached according to the optical feedback of the reflective layer R4, and the resonator 22 does not reach Q-switched laser oscillation.

[0089] Thereafter, when the solid-state laser medium 12 is in a fully excited state, the output of the spontaneously emitted light from the solid-state laser medium 12 increases. When the output of the spontaneously emitted light exceeds a certain value, the light absorption rate of the saturable absorber 13 drops sharply. As a result, the spontaneously emitted light from the solid-state laser medium 12 has a reduced loss in the saturable absorber 13, and resonance occurs between the reflective layer R2 and the reflective layer R4. This causes an induced discharge in the solid-state laser medium 12. Accordingly, the resonator 22 reaches Q-switched laser oscillation, and a Q-switched laser pulse is released from the reflective layer R4. This light becomes the emitted light from the light-emitting element 1.

[0090] Furthermore, the light emitting element 1 may be arranged on a semiconductor substrate such as a GaAs substrate, etc. In this case, the light emitting element 1 may be arranged to form a top emission type with respect to the semiconductor substrate or may be arranged to form a bottom emission type.

[0091] In addition, despite Figure 2 The light emitting element 1 is arranged in Figure 1 The interior of the distance measuring device 100 is shown, but it can be used for purposes other than distance measurement. For example, Figure 2 The light emitting element 1 shown can be arranged in a medical device to provide medical purposes.

[0092] Figure 3 : is a block diagram showing the structure of the distance measurement device 100 according to the first embodiment.

[0093] and Figure 1 similar, Figure 3 The light emitting element 1, the photodiode 3, the light receiving element 4 and the arithmetic operation circuit 5 inside the distance measuring device 100 are shown, and the illustration of the half mirror 2 is omitted. Figure 3As shown, the distance measuring device 100 includes a driving circuit 111 as an example of a driving unit, a timing detection circuit 112 as an example of a transmission timing detection unit, a timing detection circuit 113 as an example of a light receiving timing detection unit, a time difference detection circuit 114 as an example of a difference detection unit, and a distance / direction calculation circuit 115 as an example of a distance measuring unit. The driving circuit 111 is included inside the light emitting device 101, and the timing detection circuit 112, the timing detection circuit 113, the time difference detection circuit 114, and the distance / direction calculation circuit 115 are included inside the arithmetic operation circuit 5 of the light receiving device 102.

[0094] The driving circuit 111 is a circuit that drives the light emitting element 1. When the light emitting element 1 is driven, the driving circuit 111 supplies current (driving current) to the electrode provided in the semiconductor portion 11. As a result, the current is injected into the active layer 33, and light L ( Figure 1 ). As described above, the light L emitted from the light emitting element 1 includes not only the light L2 corresponding to the oscillation light but also the light L1 corresponding to the excitation light. The photodiode 3 outputs a signal indicating the detection result of the light L1, and the light receiving element 4 outputs a signal indicating the light reception result of the light L2' which is the reflected light of the light L2.

[0095] The timing detection circuit 112 receives a signal indicating the detection result of the light L1 from the photodiode 3. In addition, the timing detection circuit 112 detects the emission timing of the light L2 based on the detection result of the light L1. The emission timing of the light L2 is the timing at which the light L2 is emitted from the light emitting element 1. The timing detection circuit 112 detects, for example, the emission time t0 of the light L2 from the light emitting element 1 as the emission timing of the light L2. In addition, the timing detection circuit 112 may detect the emission timing in a form other than the emission time t0.

[0096] As a result of the study, it has been understood that the intensity of the light L1 emitted from the light emitting element 1 changes according to the emission timing of the light L2 from the light emitting element 1. For example, it has been checked that the intensity of the light L1 emitted from the light emitting element 1 changes in synchronization with the emission time t0 of the light L2 from the light emitting element 1. Therefore, in order to detect the emission timing of the light L2, the timing detection circuit 112 receives a signal indicating the detection result of the light L1. According to the present embodiment, by using the phenomenon that the intensity of the light L1 changes according to the emission timing of the light L2, the emission timing of the light L2 can be detected from the detection result of the light L1. The signal received by the timing detection circuit 112 from the photodiode 3 is, for example, a signal indicating the detection result of the intensity of the light L1.

[0097] The timing detection circuit 113 receives a signal indicating a light reception result of the light L2' from the light receiving element 4. The timing detection circuit 113 detects the light reception timing of the light L2' based on the light reception result of the light L2'. The light reception timing of the light L2' is the timing at which the light receiving element 4 receives the light L2'. The timing detection circuit 113 detects, for example, a light reception time t of the light L2' by the light receiving element 4 as the light reception timing of the light L2'. In addition, the timing detection circuit 113 may detect the light reception time in a form other than using the light reception time t.

[0098] The time difference detection circuit 114 receives a signal indicating the emission timing of the light L2 from the timing detection circuit 112, and receives a signal indicating the light reception timing of the light L2' from the timing detection circuit 113. In addition, the time difference detection circuit 114 detects the difference between the emission timing of the light L2 and the light reception timing of the light L2'. The difference is, for example, the time difference Δt between the emission time t0 of the light L2 and the light reception time t of the light L2' (Δt=t-t0).

[0099] The distance / direction calculation circuit 115 receives the difference between the emission timing of the light L2 and the light reception timing of the light L2' from the time difference detection circuit 114. In addition, the distance / direction calculation circuit 115 performs distance measurement on the object S based on the received difference. More specifically, the distance / direction calculation circuit 115 calculates the distance between the object S and the distance measurement device 100 using the received difference. In a second embodiment described below, the distance / direction calculation circuit 115 also calculates the direction of the object S relative to the distance measurement device 100 using the received difference.

[0100] As described above, by using the phenomenon that the intensity of light L1 changes according to the emission timing of light L2, the distance measuring device 100 according to the present embodiment detects the emission timing of light L2 from the detection result of light L1. If the emission timing of light L2 is detected from the detection result of light L2, it is necessary to use an expensive photodetector (for example, an InGaAs photodetector) having a sensitivity at 1030nm. On the other hand, in the case of detecting the emission timing of light L2 based on the detection result of light L1, an inexpensive photodetector (for example, a Si photodetector) having a sensitivity at 940nm can be used. Therefore, according to the present embodiment, by using the above phenomenon, the emission timing of light L2 can be easily detected. The photodiode 3 according to the present embodiment can be formed, for example, inside a Si (silicon) substrate.

[0101] Figure 4 : is a block diagram showing the structure of a distance measurement device 100 of a modified example of the first embodiment.

[0102] The distance measuring device 100 ( Figure 4 ) has the same Figure 3 However, the distance measuring device 100 of this modified example includes the timing detection circuit 112 not in the light receiving device 102 but in the light emitting device 101. Figure 4 As shown, the arithmetic operation circuit 5 of the present modification example includes a timing detection circuit 113 , a time difference detection circuit 114 , and a distance / direction calculation circuit 115 . Figure 3 The distance measuring device 100 shown, Figure 4 The distance measuring device 100 and Figure 4 The illustrated light emitting device 101 is an example of an optical device according to the present disclosure.

[0103] Figure 5 is a graph for describing the operation of the light emitting element 1 according to the first embodiment.

[0104] Figure 5 The carrier density of the driving current, the photon density of the light L1, and the photon density of the light L2 are shown relative to time. Figure 5 The inversion distribution density of the solid-state laser medium 12 (Yb:YAG) and the carrier density of the base level of the saturable absorber 13 (Cr:YAG) are shown with respect to time.

[0105] Figure 5 Each white circle shown shows the timing of the decrease in the intensity of the light L1 emitted from the light emitting element 1. The decrease in the intensity of the light L1 occurs at the timing of the emission of the light L2 (pulse light) from the light emitting element 1. Therefore, by detecting the timing of the decrease in the intensity of the light L1, the emission timing of the light L2 from the light emitting element 1 can be detected.

[0106] Figure 5 The excitation start time T1 of the light L1, the times T2 and T3 when the intensity of the light L1 decreases, and the time differences ΔT1, ΔT2, and ΔT3 between such times are shown. More specifically, ΔT1=T2-T1, ΔT2=T3-T2, and ΔT3=T4-T3 (T4 represents the time when the intensity of the light L1 decreases after T3) are satisfied. The pulse light included in the light L2 is emitted from the light emitting element 1 at times T2, T3, etc. The time differences ΔT1, ΔT2, and ΔT3 correspond to the differences between the emission times of the pulse light included in the light L2. In addition, the photon density of the light L2 increases and decreases during an extremely short time (for example, 0.01ns to 1ns) near the times T2 and T3.

[0107] Next, various modification examples of the present embodiment will be described.

[0108] Figure 6 is a cross-sectional view showing the structure of a light emitting element 1 according to a modified example of the first embodiment.

[0109] exist Figure 6 In the modified example shown in A of FIG. 1 , the light emitting element 1 is arranged on the substrate 42 through the p metal layer 41. The semiconductor portion 11, the solid-state laser medium 12 and the saturable absorber 13 of this modified example are sequentially arranged on the p metal layer 41. The p metal layer 41 serves as a metal electrode for supplying current to the active layer 33. The substrate 42 is, for example, a semiconductor substrate such as a silicon carbide (SiC) substrate or an insulating substrate such as a silicon nitride (SiN) substrate. In this modified example, the half mirror 2 and the photodiode 3 are arranged on the resonator 22 side of the light emitting element 1.

[0110] exist Figure 6 In the modified example shown in B, the light emitting element 1 has Figure 6 The structure of the light emitting element 1 shown in A is similar to that of the light emitting element 1. However, the photodiode 3 of this modification example is provided inside the substrate 42, and is therefore arranged on the resonator 21 side of the light emitting element 1. Figure 6 As shown in FIG. 1B, the photodiode 3 of the present modification example detects the light L1 emitted from the lower surface of the light emitting element 1 and passing through the opening H of the p metal layer 41. The photodiode 3 of the present modification example is provided inside the substrate 42 mounted on the light emitting element 1, so as to be integrated with the light emitting element 1. According to the present modification example, the alignment operation of the light emitting element 1, the half mirror 2, and the photodiode 3 may be unnecessary, the size of the distance measuring device 100 may be reduced, and the impact resistance of the distance measuring device 100 may be improved.

[0111] Figure 7 is a cross-sectional view showing the structure of a light emitting element 1 according to a modified example of the first embodiment.

[0112] The light emitting element 1 of the present modification example includes the semiconductor portion 11, the solid-state laser medium 12, and the saturable absorber 13 described above, and further includes an n-contact layer 43, a substrate 44, and an undoped semiconductor layer 45. In addition, Figure 7 The n-DBR layer 31, the active layer 33, and the p-DBR layer 36 inside the semiconductor portion 11 are shown, and the cladding layer 32, the cladding layer 34, and the oxide layer 35 are omitted. The n-contact layer 43 and the substrate 44 are sequentially arranged between the n-DBR layer 31 and the solid-state laser medium 12, and the non-doped semiconductor layer 45 is arranged between the n-DBR layer 31 and the photodiode 3 to be described below. For example, the n-type contact layer 43, the substrate 44, and the non-doped semiconductor layer 45 are respectively a GaAs layer containing an n-type dopant, a GaAs substrate, and a non-doped GaAs layer. The non-doped semiconductor layer 45 is arranged to increase the resistance between the light-emitting element 1 and the photodiode 3.

[0113] also, Figure 7The photodiode 3 installed in the light emitting element 1 is shown. The photodiode 3 of this modification example includes an n-type semiconductor layer 51, an active layer 52, and a p-type semiconductor layer 53. The photodiode 3 of this modification example is arranged on the resonator 21 side of the light emitting element 1. Figure 7 As shown, the photodiode 3 of the present modification example detects the light L1 emitted from the lower surface of the light emitting element 1. According to the present modification example, the alignment operation of the light emitting element 1, the half mirror 2, and the photodiode 3 may be unnecessary, the size of the distance measuring device 100 may be reduced, and the impact resistance of the distance measuring device 100 may be improved. The n-type semiconductor layer 51, the active layer 52, and the p-type semiconductor layer 53 are, for example, a GaAs layer containing an n-type dopant, a layer having a quantum well structure, and a GaAs layer containing a p-type dopant, respectively.

[0114] also, Figure 7 An n metal layer 61 disposed on the lower surface of the n contact layer 43, a p metal layer 62 disposed on the lower surface of the p-DBR layer 36, an n metal layer 63 disposed on the lower surface of the n-type semiconductor layer 51, and a p metal layer 64 disposed on the lower surface of the p-type semiconductor layer 53 are shown. The n metal layer 61, the p metal layer 62, and the n metal layer 63 have a ring shape, and the p metal layer 64 has a disk shape. The n metal layer 61 and the p metal layer 62 are used as metal electrodes for driving the semiconductor portion 11, and the n metal layer 63 and the p metal layer 64 are used as metal electrodes for outputting signals from the photodiode 3.

[0115] Figure 8 : is a schematic diagram showing the structure of a distance measurement device 100 of a modified example of the first embodiment.

[0116] The distance measuring device 100 ( Figure 8 ) has the same Figure 1 The distance measuring device 100 shown in FIG. Figure 6 Similar to the light emitting element 1 shown in B of FIG. 1 , the light emitting element 1 of this modified example is arranged on a substrate 42 through a p metal layer 41, and a photodiode 3 is provided inside the substrate 42. According to this modified example, the alignment operation of the light emitting element 1, the half mirror 2, and the photodiode 3 may be unnecessary, the size of the distance measuring device 100 may be reduced, and the impact resistance of the distance measuring device 100 may be improved.

[0117] Fig. 9 : is a block diagram showing the structure of a distance measurement device 100 of a modified example of the first embodiment.

[0118] Fig. 9 Shows Figure 8 The block structure of the distance measuring device 100 is shown. Fig. 9The photodiode 3 and the light emitting element 1 are integrated together. In addition, such a block structure can be realized by using Figure 7 The light emitting element 1 shown is not used Figure 6 The light-emitting element 1 is shown in B.

[0119] As described above, the distance measurement device 100 according to the present embodiment detects the emission timing of the light L2 (oscillation light) based on the detection result of the light L1 (excitation light). Therefore, according to the present embodiment, for example, the emission timing of the light L2 can be detected using the low-cost photodiode 3 or the like, so that the emission timing of the light L2 can be appropriately detected.

[0120] (Second Embodiment)

[0121] Fig.10 is a perspective view showing the structure of a light emitting device 101 according to a second embodiment.

[0122] The light emitting device 101 according to the present embodiment includes a plurality of light emitting elements 1, a half mirror 2, and a photodiode 3. Such light emitting elements 1 are formed using a semiconductor portion 11, a solid-state laser medium 12, and a saturable absorber 13 common to the light emitting elements 1, so as to be arranged in a two-dimensional array form. These are referred to as a light emitting element array 71. Also in the present embodiment, the semiconductor portion 11 and the solid-state laser medium 12 form a resonator 21, and the solid-state laser medium 12 and the saturable absorber 13 form a resonator 22.

[0123] The light L emitted from each light emitting element 1 is separated into light L1 and light L2 by the half mirror 2. The light L1 is detected by the photodiode 3, and the light L2 is emitted from the light emitting device 101 to the outside.

[0124] In the present embodiment, a plurality of light emitting elements 1 are sequentially driven, and light L is sequentially emitted from such light emitting elements 1. Accordingly, light L from such light emitting elements 1 can be detected by one photodiode 3. In addition, by driving such light emitting elements 1 not simultaneously but sequentially, it is possible to reduce the amount of heat generated by each light emitting element 1. In addition, by configuring the light emitting device 101 using a plurality of light emitting elements 1, light L2 can be emitted to a wide range.

[0125] Fig.11 1 is a perspective view showing the structure of a light emitting device 101 of a comparative example of the second embodiment.

[0126] The light emitting device 101 of this comparative example includes a plurality of light emitting elements 1, a plurality of half mirrors 2, and a plurality of photodiodes 3. These will be referred to as a light emitting element array 71, a half mirror array 72, and a photodiode array 73, respectively. Light L emitted from each light emitting element 1 is separated into light L1 and light L2 by the corresponding half mirror 2. Light L1 is detected by the corresponding photodiode 3, and light L2 is emitted from the light emitting device 101 to the outside.

[0127] According to this comparative example, such light emitting elements 1 can be driven not only sequentially but also simultaneously. However, in this comparative example, there is a problem that it is difficult to ensure a space for arranging the half mirror 2 and the photodiode 3. In addition, in this comparative example, there is a problem of crosstalk that causes the light L1 incident on a certain photodiode 3 to be incident on another photodiode 3. Fig.11 An appearance is shown in which crosstalk occurs between the photodiodes 3. Such a problem can be solved by a modification example to be described below.

[0128] Fig.12 is a cross-sectional view showing the structure of a light emitting device 101 of a modified example of the second embodiment.

[0129] exist Fig.12 In the modified example shown in A of FIG. 1 , the light emitting device 101 includes a plurality of light emitting elements 1 and a plurality of photodiodes 3. Such light emitting elements 1 are formed using a semiconductor portion 11, a solid-state laser medium 12, and a saturable absorber 13 common to the light emitting elements 1, and such photodiodes 3 are formed inside a photodiode layer 46 common to the photodiodes 3. Examples of the photodiode layer 46 include semiconductor layers such as a polycrystalline silicon layer, a compound semiconductor layer, and the like. Fig.12 A shows a light emitting element array 71 having a plurality of light emitting elements 1 arranged in a two-dimensional array and a photodiode array 73 having a plurality of photodiodes 3 arranged in a two-dimensional array. Also in this modified example, the semiconductor portion 11 and the solid-state laser medium 12 form a resonator 21, and the solid-state laser medium 12 and the saturable absorber 13 form a resonator 22.

[0130] In addition, compared with the first embodiment Figure 6 Similar to B, Fig.12 A shows a p-metal layer 41 and a substrate 42. The semiconductor portion 11, the solid-state laser medium 12, and the saturable absorber 13 are sequentially stacked on the upper surface of the substrate 42 through the p-metal layer 41. The photodiode layer 46 is provided on the lower surface of the substrate 42. The upper surface and the lower surface of the substrate 42 are examples of the first surface and the second surface of the present disclosure, respectively.

[0131] like Fig.12As shown in A, each photodiode 3 of the present modification example detects light L1 emitted from the lower surface of the corresponding light emitting element 1 and passing through the opening H' of the p metal layer 41 and the substrate 42. The light emitting element array 71 and the photodiode array 73 of the present modification example are arranged on the upper surface and the lower surface of the same substrate 42, so as to be integrated together. According to the present modification example, the alignment operation of the light emitting element 1, the half mirror 2 and the photodiode 3 may be unnecessary, the size of the distance measuring device 100 may be reduced, and the impact resistance of the distance measuring device 100 may be improved. In addition, according to the present modification example, by arranging each photodiode 3 in the vicinity of the corresponding light emitting element 1, the occurrence of crosstalk may be suppressed.

[0132] exist Fig.12 In the modified example shown in B, the light emitting device 101 has Fig.12 The structure is similar to the light emitting device 101 shown in A. However, the photodiode layer 46 of this modification example is provided between the upper surface of the substrate 42 and the lower surface of the p metal layer 41. According to this modification example, each photodiode 3 can be arranged closer to the corresponding light emitting element 1.

[0133] Fig.13 : is a schematic diagram showing the structure of a distance measurement device 100 according to the second embodiment.

[0134] According to the distance measuring device 100 ( Fig.13 ) has the same Figure 8 The distance measuring device 100 according to the first embodiment shown in FIG. 1 is similar in structure to the distance measuring device 100 according to the first embodiment shown in FIG. Fig.12 The light emitting device 101 shown in A is used as the light emitting device 101 . To this end, the distance measuring device 100 according to the present embodiment includes a light emitting element array 71 and a photodiode array 73 in the light emitting device 101 .

[0135] Furthermore, the distance measuring device 100 according to the present embodiment includes a light receiving element array 74 provided in the light receiving device 102, a lens 75 provided in the light emitting device 101, and a lens 76 provided in the light receiving device 102. The light receiving element array 74 has a plurality of light receiving elements 4 arranged in a two-dimensional array.

[0136] The distance measuring device 100 according to the present embodiment transmits the light L2 emitted from each light emitting element 1 to the object S through the lens 75. The light receiving element array 74 receives the light L2' from the object S through the lens 76. Each light receiving element 4 outputs a signal indicating the light reception result of the light L2' to the arithmetic operation circuit 5. On the other hand, each photodiode 3 outputs a signal indicating the detection result of the light L1 to the arithmetic operation circuit 5. In general, although Fig.13The number of arrows representing light L2' is the same as that in Fig.13 The number of arrows indicating the light L2 is the same in FIG. 1 , but when the drawings are more accurately shown, the illustration of the arrows indicating the light L2 ′ is partially omitted here for easy understanding of the drawings.

[0137] Fig.14 : is a block diagram showing the structure of a distance measurement device 100 according to the second embodiment.

[0138] Fig.14 Show Fig.13 The block structure of the distance measuring device 100 is shown. Fig.14 The structure shown is Fig. 9 The structure shown according to the first embodiment is similar, but Fig.14 A light emitting element array 71 , a photodiode array 73 , and a light receiving element array 74 are shown instead of the light emitting elements 1 , the photodiodes 3 , and the light receiving elements 4 . Fig.14 There is shown an appearance in which the photodiode array 73 and the light emitting element array 71 are integrated together. The arithmetic operation circuit 5 according to the present embodiment can operate similarly to the arithmetic operation circuit 5 according to the first embodiment.

[0139] The driving circuit 111 according to the present embodiment is a scanning driving circuit that sequentially drives a plurality of light emitting elements 1 included in the light emitting element array 71. Accordingly, light L is sequentially emitted from such light emitting elements 1. In this case, the distance measuring device 100 according to the present embodiment may include Fig.10 The light emitting device 101 shown or Fig.12 The light emitting device 101 shown in B, instead of comprising Fig.12 The light emitting device 101 is shown in A. The scanning order when the plurality of light emitting elements 1 are sequentially driven may be any order.

[0140] Similar to the distance / direction calculation circuit 115 according to the first embodiment, the distance / direction calculation circuit 115 according to the present embodiment performs distance measurement on the object S. However, by using the detection results of the light L1 according to the plurality of photodiodes 3 and the light reception results of the light L2′ according to the plurality of light receiving elements 4, the distance / direction calculation circuit 115 according to the present embodiment calculates the distance between the object S and the distance measuring device 100 and the direction of the object S relative to the distance measuring device 100.

[0141] Fig.15 : is a block diagram showing the structure of a distance measurement device 100 of a modified example of the second embodiment.

[0142] The distance measuring device 100 according to the present modification example has Fig.14The distance measuring device 100 shown in FIG. 1 is a block structure similar to that of the distance measuring device 100 shown in FIG. 1 . However, the driving circuit 111 of the present modification example is a simultaneous driving circuit that simultaneously drives a plurality of light emitting elements 1 included in the light emitting element array 71. Accordingly, light L is emitted from such light emitting elements 1 at the same time. In this case, the distance measuring device 100 of the present modification example may include Fig.12 The light emitting device 101 shown in B, instead of comprising Fig.12 A light emitting device 101 is shown in FIG.

[0143] In addition, the driving circuit 111 of the present modified example can simultaneously drive all the light emitting elements 1 within the light emitting element array 71 or can simultaneously drive some of the light emitting elements 1 within the light emitting element array 71. For example, in a case where the light emitting element array 71 includes a plurality of groups and each group includes a plurality of light emitting elements 1, the driving circuit 111 of the present modified example can simultaneously drive the light emitting elements 1 of each group. More specifically, the driving circuit 111 of the present modified example can adopt simultaneous driving within each group and sequential driving between groups, such as a case where a plurality of light emitting elements 1 within a first group are simultaneously driven, a plurality of light emitting elements 1 within a second group are subsequently simultaneously driven, and a plurality of light emitting elements 1 within a third group are subsequently simultaneously driven.

[0144] Fig.16 : is a block diagram showing the structure of a distance measurement device 100 of a modified example of the second embodiment.

[0145] The distance measuring device 100 of this modified example has Fig.14 The distance measuring device 100 shown in FIG. 1 has a similar block structure. However, the arithmetic operation circuit 5 of the present modification example includes the time difference detection circuit 114 and the distance / direction calculation circuit 115 , but does not include the timing detection circuit 112 and the timing detection circuit 113 .

[0146] The time difference detection circuit 114 of the present modified example receives a signal indicating the detection result of light L1 from the photodiode array 73 (photodiode 3), and receives a signal indicating the light reception result of light L2 from the light receiving element array 74 (light receiving element 4). The time difference detection circuit 114 of the present modified example further detects the difference between the emission timing of light L2 and the light reception timing of light L2' based on such a signal. For example, the difference is the time difference Δt (Δt=t-t0) between the emission time t0 of light L2 and the light reception time t of light L2'. In this way, the time difference detection circuit 114 of the present modified example has the same Fig.14 The functions of the timing detection circuit 112, the timing detection circuit 113 and the time difference detection circuit 114 shown in FIG. Fig.14Similar to the distance / direction calculation circuit 115 shown, the distance / direction calculation circuit 115 of the present modification example performs distance measurement on the object S based on the received difference value.

[0147] As described above, similar to the distance measuring device 100 according to the first embodiment, the distance measuring device 100 of the present embodiment detects the emission timing of the light L2 (oscillation light) based on the detection result of the light L1 (excitation light). Therefore, according to the present embodiment, the emission timing of the light L2 can be appropriately detected, for example, the emission timing of the light L2 can be detected using a low-cost photodiode 3 or the like. In addition, according to the present embodiment, by adopting the light emitting element array 71 and the photodiode array 73, sequential driving and simultaneous driving of multiple light emitting elements 1 can be adopted. Even in the case of driving multiple light emitting elements 1 simultaneously, generally, the emission timing of the light L2 is slightly different for each light emitting element 1, and therefore it is preferable to use multiple photodiodes 3.

[0148] (Third Embodiment)

[0149] Fig.17 is a block diagram showing the structure of a distance measurement device 100 according to the third embodiment.

[0150] The distance measuring device 100 ( Fig.17 ) has the same distance measuring device 100 as the first embodiment ( Figure 3 ) is a similar structure. However, the distance measurement device 100 of the present embodiment includes a current detection circuit 3' instead of the photodiode 3. Similar to the photodiode 3, the current detection circuit 3' is an example of a detector of the present disclosure.

[0151] When the light emitting element 1 is driven, the driving circuit 111 supplies a driving current to the light emitting element 1. As a result, light L ( Figure 1 ). The light L emitted from the light emitting element 1 includes not only the light L2 corresponding to the oscillation light but also the light L1 corresponding to the excitation light. The photodiode 3 according to the first embodiment detects the light L1 and outputs a signal indicating the detection result of the light L1 to the timing detection circuit 112. In contrast, the current detection circuit 3' according to the present embodiment detects the drive current of the light emitting element 1 and outputs a signal indicating the detection result of the drive current to the timing detection circuit 112.

[0152] In this embodiment, the timing detection circuit 112 receives a signal indicating the detection result of the drive current from the current detection circuit 3'. In addition, the timing detection circuit 112 detects the emission timing of the light L2 based on the detection result of the drive current. The timing detection circuit 112 detects, for example, the emission time t0 of the light L2 from the light emitting element 1 as the emission timing of the light L2.

[0153] As a result of the study, it can be understood that the value of the driving current of the light emitting element 1 changes according to the emission timing of the light L2 from the light emitting element 1. For example, it can be checked that the value of the driving current of the light emitting element 1 changes in synchronization with the emission time t0 of the light L2 from the light emitting element 1. Therefore, in order to detect the emission timing of the light L2, the timing detection circuit 112 receives a signal indicating the detection result of the driving current. According to the present embodiment, by using the phenomenon that the value of the driving current changes according to the emission timing of the light L2, the emission timing of the light L2 can be detected from the detection result of the driving current. The signal received from the current detection circuit 3' by the timing detection circuit 112 is, for example, a signal indicating the detection result of the value of the driving current.

[0154] Figure 5 The timing of the change in the value of the driving current of the light emitting element 1 is shown in FIG. Figure 5 , the photon density of light L1 decreases at the timing indicated by the white circle, and the carrier density of the driving current also increases at the same timing. The timing at which the photon density of light L1 decreases corresponds to the timing at which the intensity of light L1 emitted from the light emitting element 1 decreases. On the other hand, the timing at which the carrier density of the driving current increases corresponds to the timing at which the value of the driving current increases. The decrease in the intensity of light L1 and the increase in the value of the driving current occur at the timing at which light L2 (pulse light) is emitted from the light emitting element 1. Therefore, by detecting the timing at which the value of the driving current increases, the emission timing of light L2 from the light emitting element 1 can be detected.

[0155] The operations of the timing detection circuit 113 , the time difference detection circuit 114 , the distance / direction calculation circuit 115 , and the like according to the present embodiment are similar to those according to the first embodiment.

[0156] In addition, the current detection circuit 3' according to the present embodiment can be applied to any other distance measuring device 100 instead of being applied to Figure 3 The distance measuring device 100 shown in FIG. 1 can be used, for example, in Figure 4 , Fig. 9 , Fig.14 , Fig.15 or Fig.16 A distance measuring device 100 is shown.

[0157] Fig.18 : is a block diagram showing the structure of a distance measurement device 100 of a modified example of the third embodiment.

[0158] Fig.17 The distance measuring device 100 shown includes a current detection circuit 3' instead of the photodiode 3. On the other hand, Fig.18 The distance measuring device 100 shown includes a current detection circuit 3' and a photodiode 3. Fig.18), the emission timing of the light L2 can be detected based on the detection result of the light L1 by the photodiode 3, and the emission timing of the light L2 can be detected based on the detection result of the driving current by the current detection circuit 3'. In other words, according to this modified example, any one of the photodiode 3 and the current detection circuit 3' to be used can be selected.

[0159] Although the embodiments of the present disclosure have been described above, these embodiments may be implemented with various modifications without departing from the essence of the present disclosure. For example, a combination of two or more embodiments may be implemented.

[0160] Here, the present disclosure may have the following configurations. (1)

[0162] An optical device includes: a light-emitting element including a semiconductor portion, a solid-state laser medium, and a saturable absorber and emitting light of a second wavelength, the semiconductor portion being included in a first resonator that resonates light of a first wavelength and oscillates the light of the first wavelength, the solid-state laser medium being included in the first resonator and in a second resonator that resonates light of a second wavelength and oscillates the light of the second wavelength, the saturable absorber being included in the second resonator; a detector that detects the light of the first wavelength or a driving current of the light-emitting element; and an emission timing detection unit that detects the emission timing of the light of the second wavelength based on a detection result of the light of the first wavelength or the driving current of the light-emitting element acquired using the detector. (2)

[0164] The optical device according to (1), wherein the intensity of the light of the first wavelength or the value of the driving current of the light emitting element changes according to the emission timing of the light of the second wavelength. (3)

[0166] The optical device according to (1), further including: a distance measurement unit that performs distance measurement based on a detection result of the emission timing of the light of the second wavelength acquired using the emission timing detection unit. (4)

[0168] The optical device according to (3) further includes: a light receiving element that receives reflected light of the light of the second wavelength, wherein the distance measurement unit performs distance measurement based on a detection result of the emission timing of the light of the second wavelength obtained using the emission timing detection unit and a light reception result of the reflected light obtained using the light receiving element. (5)

[0170] The optical device according to (4) further includes: a light reception timing detection unit that detects a light reception timing of the reflected light based on a light reception result of the reflected light obtained using the light receiving element, wherein the distance measurement unit performs distance measurement based on a detection result of the emission timing of the light of the second wavelength obtained using the emission timing detection unit and a detection result of the light reception timing of the reflected light obtained using the light reception timing detection unit. (6)

[0172] The optical device according to (5), further including: a difference detection unit that detects a difference between an emission timing of the light of the second wavelength and a light reception timing of the reflected light, wherein the distance measurement unit performs distance measurement based on the difference detected using the difference detection unit. (7)

[0174] The optical device according to (1), wherein the optical device is a distance measurement device that performs distance measurement based on a detection result of emission timing of the light of the second wavelength acquired using the emission timing detection unit. (8)

[0176] The optical device according to (1), wherein the optical device is a light emitting device that emits light of the second wavelength, and is included in the distance measuring device together with a light receiving device that receives light of the second wavelength. (9)

[0178] An optical device according to (1), wherein the light-emitting element includes: a first reflection layer located in the semiconductor portion and reflecting light of a first wavelength; a second reflection layer located on the first surface of the solid-state laser medium and reflecting light of a second wavelength; a third reflection layer located on the second surface of the solid-state laser medium and reflecting light of the first wavelength; a fourth reflection layer located on the surface of the saturable absorber and reflecting light of the second wavelength; and a fifth reflection layer located in the semiconductor portion, located on the solid-state laser medium side of the first reflection layer, and reflecting a portion of the light of the first wavelength. (10)

[0180] The optical device according to (1), wherein the detector is arranged on the second resonator side of the light emitting element. (11)

[0182] The optical device according to (1), wherein the detector is arranged on the first resonator side of the light emitting element. (12)

[0184] The optical device according to (1), wherein the detector is installed in the light emitting element. (13)

[0186] The optical device according to (1), wherein the light emitting element is provided on the first surface side of the substrate, and the detector is provided on the first surface side of the substrate and in a layer provided between the substrate and the light emitting element. (14)

[0188] The optical device according to (1), wherein the light emitting element is provided on the first surface side of the substrate, and the detector is provided in a layer provided on the second surface side of the substrate. (15)

[0190] The optical device according to (1), wherein the optical device includes a plurality of light emitting elements arranged in an array as the light emitting element. (16)

[0192] The optical device according to (15), wherein the optical device further includes a plurality of detectors arranged in an array in the same layer as the detector. (17)

[0194] The optical device according to (15) further includes: a driving unit that drives the plurality of light emitting elements, wherein the driving unit sequentially excites light from the plurality of light emitting elements by scanning the plurality of light emitting elements. (18)

[0196] The optical device according to (15) further includes: a driving unit that drives the plurality of light emitting elements, wherein the driving unit simultaneously excites light from the plurality of light emitting elements by driving the plurality of light emitting elements at the same time. (19)

[0198] A distance measuring device includes: a light emitting element including a semiconductor portion, a solid-state laser medium, and a saturable absorber and emitting light of a second wavelength, the semiconductor portion being included in a first resonator that resonates light of a first wavelength and oscillates the light of the first wavelength, the solid-state laser medium being included in the first resonator and in a second resonator that resonates light of a second wavelength and oscillates the light of the second wavelength, the saturable absorber being included in the second resonator; a detector that detects the light of the first wavelength or a driving current of the light emitting element; a light receiving element that receives reflected light of the light of the second wavelength; and a distance measuring unit that performs distance measurement based on a detection result of the light of the first wavelength or the driving current of the light emitting element acquired using the detector and a light reception result of the reflected light acquired using the light receiving element. (20)

[0200] The distance measuring device according to (19) further includes: an emission timing detection unit that detects the emission timing of light of a second wavelength based on a detection result of light of a first wavelength or a driving current of a light-emitting element obtained using a detector, and the distance measuring unit performs distance measurement based on the detection result of the emission timing of light of the second wavelength obtained using the emission timing detection unit and a light reception result of the reflected light obtained using a light receiving element.

[0201] Reference Mark List

[0202] 1 Light-emitting element

[0203] 2 Half mirror

[0204] 3 Photodiode

[0205] 3' Current detection circuit

[0206] 4 Light receiving element

[0207] 5 Arithmetic operation circuit

[0208] 11 Semiconductor Division

[0209] 12 Solid-state laser media

[0210] 13 Saturable absorber

[0211] 21 Resonator

[0212] 22 Resonator

[0213] 31 n-DBR layer

[0214] 32 Coating

[0215] 33 Active layer

[0216] 34 Coating

[0217] 35 Oxide layer

[0218] 36 p-DBR layer

[0219] 41p metal layer

[0220] 42 substrate

[0221] 43 n contact layer

[0222] 44 substrate

[0223] 45 Undoped semiconductor layer

[0224] 46 Photodiode layer

[0225] 51 n-type semiconductor layer

[0226] 52 Active layer

[0227] 53 p-type semiconductor layer

[0228] 61n Metal layer

[0229] 62p metal layer

[0230] 63n metal layer

[0231] 64p metal layer

[0232] 71 Light-emitting element array

[0233] 72 Half Mirror Array

[0234] 73 Photodiode Array

[0235] 74 light receiving element array

[0236] 75 Lens

[0237] 76 Lens

[0238] 100 Distance measuring device

[0239] 101 Lighting Device

[0240] 102 Light receiving device

[0241] 111 Driving Circuit

[0242] 112 Timing detection circuit

[0243] 113 Timing detection circuit

[0244] 114 Time difference detection circuit

[0245] 115 Distance / direction calculation circuit.

Claims

1. An optical device, comprising: a light emitting element including a semiconductor portion, a solid-state laser medium, and a saturable absorber, and emitting light of a second wavelength, the semiconductor portion being included in a first resonator that resonates light of a first wavelength and oscillates the light of the first wavelength, the solid-state laser medium being included in the first resonator and in a second resonator that resonates light of a second wavelength and oscillates the light of the second wavelength, and the saturable absorber being included in the second resonator; a detector for detecting the light of the first wavelength or the driving current of the light emitting element; as well as An emission timing detection unit detects emission timing of the light of the second wavelength based on a detection result of the light of the first wavelength or the drive current of the light emitting element acquired using the detector.

2. The optical device according to claim 1, wherein: The intensity of the light of the first wavelength or the value of the driving current of the light emitting element changes according to the emission timing of the light of the second wavelength.

3. The optical device according to claim 1, further comprising: A distance measurement unit performs distance measurement based on a detection result of the emission timing of the light of the second wavelength acquired using the emission timing detection unit.

4. The optical device according to claim 3, further comprising: a light receiving element that receives reflected light of the light of the second wavelength, Herein, the distance measurement unit performs the distance measurement based on a detection result of the emission timing of the light of the second wavelength acquired using the emission timing detection unit and a light reception result of the reflected light acquired using the light receiving element.

5. The optical device according to claim 4, further comprising: a light reception timing detection unit that detects a light reception timing of the reflected light based on a light reception result of the reflected light acquired using the light receiving element, The distance measurement unit performs the distance measurement based on a detection result of the emission timing of the light of the second wavelength acquired by the emission timing detection unit and a detection result of the light reception timing of the reflected light acquired by the light reception timing detection unit.

6. The optical device according to claim 5, further comprising: a difference detection unit that detects a difference between the emission timing of the light of the second wavelength and the light reception timing of the reflected light, Herein, the distance measurement unit performs the distance measurement based on the difference value detected using the difference value detection unit.

7. The optical device according to claim 1, wherein: The optical device is a distance measuring device that performs distance measurement based on a detection result of the emission timing of the light of the second wavelength acquired using the emission timing detection unit.

8. The optical device according to claim 1, wherein: The optical device is a light emitting device that emits light of the second wavelength, and is included in a distance measuring device together with a light receiving device that receives light of the second wavelength.

9. The optical device according to claim 1, wherein: The light emitting element comprises: a first reflective layer located in the semiconductor portion and reflecting light of the first wavelength; a second reflective layer, located on the first surface of the solid-state laser medium and reflecting light of the second wavelength; a third reflective layer, located on the second surface of the solid-state laser medium and reflecting light of the first wavelength; a fourth reflective layer located on a surface of the saturable absorber and reflecting light of the second wavelength; and The fifth reflective layer is located in the semiconductor portion, is located on the solid laser medium side of the first reflective layer, and reflects a portion of the light of the first wavelength.

10. The optical device according to claim 1, wherein: The detector is arranged on the second resonator side of the light emitting element.

11. The optical device according to claim 1, wherein: The detector is arranged on the first resonator side of the light emitting element.

12. The optical device according to claim 1, wherein: The detector is installed in the light emitting element.

13. The optical device according to claim 1, in, The light emitting element is disposed on the first surface side of the substrate, and The detector is provided on the first surface side of the substrate and in a layer provided between the substrate and the light emitting element.

14. The optical device according to claim 1, in, The light emitting element is disposed on the first surface side of the substrate, and The detector is arranged in a layer arranged on the second surface side of the substrate.

15. The optical device according to claim 1, wherein: The optical device includes a plurality of light emitting elements arranged in an array as the light emitting elements.

16. The optical device according to claim 15, wherein: The optical device further includes a plurality of detectors arranged in an array in the same layer as the detector.

17. The optical device according to claim 15, further comprising: A driving unit drives the plurality of light emitting elements, The driving unit sequentially excites the light from the plurality of light emitting elements by scanning the plurality of light emitting elements.

18. The optical device according to claim 15, further comprising: A driving unit drives the plurality of light emitting elements, The driving unit simultaneously excites light from the multiple light emitting elements by driving the multiple light emitting elements simultaneously.

19. A distance measuring device, comprising: a light emitting element including a semiconductor portion, a solid-state laser medium, and a saturable absorber, and emitting light of a second wavelength, the semiconductor portion being included in a first resonator that resonates light of a first wavelength and oscillates the light of the first wavelength, the solid-state laser medium being included in the first resonator and in a second resonator that resonates light of a second wavelength and oscillates the light of the second wavelength, and the saturable absorber being included in the second resonator; a detector for detecting the light of the first wavelength or the driving current of the light emitting element; a light receiving element for receiving reflected light of the light of the second wavelength; as well as A distance measurement unit performs distance measurement based on a detection result of the light of the first wavelength or the driving current of the light emitting element acquired using the detector and a light reception result of the reflected light acquired using the light receiving element.

20. The distance measuring device according to claim 19, further comprising: an emission timing detection unit that detects the emission timing of the light of the second wavelength based on the detection result of the light of the first wavelength or the driving current of the light emitting element obtained using the detector, and wherein the distance measurement unit performs the distance measurement based on the detection result of the emission timing of the light of the second wavelength obtained using the emission timing detection unit and the light reception result of the reflected light obtained using the light receiving element.

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