Surface emitting laser and laser radar

Abstract

The embodiment of the utility model relates to a surface emitting laser and a laser radar. The surface emitting laser comprises a substrate; the heterojunction light-emitting array is arranged on the substrate, and the heterojunction light-emitting array comprises a plurality of heterojunction light-emitting structures; the composite regulation and control layer is arranged above the heterojunction light-emitting array; wherein the composite regulation and control layer is configured to regulate and control the far-field divergence angle of the surface emitting laser according to the arrangement position relation of the heterojunction light emitting structures, and the composite regulation and control layer is further configured to select the emergent laser polarization mode of the surface emitting laser. Regulation and control of the far-field divergence angle of the device can be realized through the composite regulation and control layer, and selection of a polarization mode can also be realized.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of surface emitting lasers, in particular to a surface emitting laser and a laser radar. BACKGROUND

[0002] A surface emitting laser (for example, a vertical cavity surface emitting laser) is a new type of surface emitting laser, which is characterized by small volume, low threshold current, easy two-dimensional integration, etc., and is widely used in optical communication, optical interconnection and other fields.

[0003] However, in the design of a vertical cavity surface emitting laser, far field divergence angle and optical power are very important to the vertical cavity surface emitting laser, but the two indicators are like the two ends of a seesaw, and it is very difficult to consider both at the same time. Usually, in order to balance the two as much as possible, the epitaxial end and the chip design end need to be considered simultaneously.

[0004] The present application plans to improve the far field divergence angle of the device without changing the epitaxial design and the chip design. CONTENT OF THE UTILITY MODEL

[0005] The main purpose of the utility model is to provide a surface emitting laser and a laser radar, aiming at solving the above technical problems in the prior art.

[0006] In a first aspect, the present application provides a surface emitting laser, comprising:

[0007] a substrate;

[0008] a heterojunction light emitting array arranged on the substrate, the heterojunction light emitting array comprising a plurality of heterojunction light emitting structures; and

[0009] a composite control layer arranged above the heterojunction light emitting array;

[0010] The composite control layer is configured to control the far field divergence angle of the surface emitting laser according to the arrangement position relationship of each heterojunction light emitting structure, and the composite control layer is also configured to select the outgoing laser polarization mode of the surface emitting laser.

[0011] In one embodiment, the heterojunction light emitting structure comprises a bottom mirror structure, an active layer, a photoelectric confinement structure and a top mirror structure, the bottom mirror structure and the top mirror structure defining a resonant cavity for emitting laser of a predetermined wavelength, and the photoelectric confinement structure is used to define the light emitting aperture of the heterojunction light emitting structure; the composite control layer is arranged on the top mirror structure; and / or

[0012] The bottom mirror structure is an N-type mirror structure, and the top mirror structure is a P-type mirror structure; and / or

[0013] The optoelectronic confinement structure includes any one of an air post type optoelectronic confinement structure, an oxide confinement type optoelectronic confinement structure, an ion implantation type optoelectronic confinement structure, and a tunnel junction type optoelectronic confinement structure.

[0014] In one embodiment, the composite control layer includes a plurality of control units, one control unit is arranged above a light emitting aperture of a heterojunction light emitting structure, and the control unit is configured to control the light output and polarization mode of the heterojunction light emitting structure; and / or

[0015] The total light output of at least one control unit is greater than the total light output of any other control unit; and / or

[0016] The general outline of the control unit is similar to the general outline of the light emitting aperture.

[0017] In one embodiment, the control unit includes a base layer and a plurality of etching patterns obtained by partially etching the base layer, and the sum of the areas of each etching pattern is the total light output.

[0018] In one embodiment, the total light output of each control unit gradually decreases in a direction from the center to the periphery of the heterojunction light emitting array; and / or

[0019] The gradual decrease of the total light output of each control unit is achieved by adjusting the two-dimensional size of the etching pattern.

[0020] In one embodiment, the total light output of the control unit located at the center of the heterojunction light emitting array is greater than the total light output of all control units located at the periphery of the heterojunction light emitting array; and / or

[0021] The total light output of each control unit located at the periphery of the heterojunction light emitting array is the same; and / or

[0022] Among the control units located at the periphery of the heterojunction light emitting array, the total light output of at least some control units is different from the total light output of the remaining control units.

[0023] In one embodiment, the total light output of the control unit located at the center of the heterojunction light emitting array is greater than the total light output of all control units located at the periphery of the heterojunction light emitting array, which is achieved by adjusting the two-dimensional size of the etching pattern.

[0024] In one embodiment, the spacing between each heterojunction light emitting structure is not completely the same; and / or

[0025] The spacing between the heterojunction light emitting structure located at the center of the heterojunction light emitting array and any two adjacent heterojunction light emitting structures is different.

[0026] In one embodiment, in the same regulating unit, the light output of at least one side is greater than that of the other side opposite to the one side.

[0027] In a second aspect, the application further provides a laser radar comprising a transmitting assembly and a receiving assembly, wherein the transmitting assembly is the surface emitting laser as described in any of the preceding embodiments.

[0028] The surface emitting laser has at least the following beneficial effects:

[0029] The surface emitting laser has at least the following beneficial effects: BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 FIG. 1 is a schematic view of a surface emitting laser in an embodiment of the application;

[0031] Figure 2 FIG. 2 is a schematic view of a cross section of the surface emitting laser in FIG. 1; Figure 1

[0032] Figures 3a-3c FIG. 5 is a schematic view of a partial structure of a heterojunction light emitting structure in another embodiment of the application;

[0033] Figures 4a-4d FIG. 5 is a schematic view of a partial structure of a heterojunction light emitting structure in another embodiment of the application;

[0034] The purposes, functional features and advantages of the surface emitting laser will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0035] In order to make the purposes, technical solutions and advantages of the application more clear, the application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0036] It can be understood that the terms "first", "second", etc. used in the application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. For example, without departing from the scope of the application, the first client can be referred to as the second client, and similarly, the second client can be referred to as the first client.

[0037] ​Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. "Multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. "Several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0038] As described in the background section of this application, in VCSEL design, both the far-field divergence angle and optical power are very important, but these two indicators are like the two ends of a seesaw, and it is very difficult to achieve both at the same time. Usually, in order to achieve the best possible balance between the two, it is necessary to consider them simultaneously from the epitaxial end and the chip design end.

[0039] Specifically, for example, in pursuit of a small far-field divergence angle, both the epitaxial layer and the chip design are done at the expense of optical power. Correspondingly, to compensate for the loss of optical power, it is necessary to increase the number of heterojunction light-emitting structures (also known as light-emitting apertures) on the chip. However, the increased number of heterojunction light-emitting structures leads to chip size, heat generation, and uneven injection current, further increasing the loss of optical power per unit of the heterojunction light-emitting structure. Uneven current injection also leads to an increase in the far-field divergence angle. When polarization requirements are introduced into VCSELs, the output optical power will be further attenuated by the polarization grating, ultimately resulting in a significant decrease in the output light intensity or photoelectric conversion efficiency in exchange for a reduction in the far-field divergence angle.

[0040] Based on this, it can be referred to Figures 1-4d This application provides a surface-emitting laser 1, including a substrate 10 and a plurality of heterojunction light-emitting structures 22 disposed on the substrate 10. Each heterojunction light-emitting structure 22 is separated by a trench (not shown). Each heterojunction light-emitting structure 22 may include: a bottom reflector structure 22a, an active layer 22b, a photoelectric confinement structure 22c and a top reflector structure 22d disposed sequentially on the substrate 10. The trench exposes a portion of the surface of the bottom reflector structure 22a. The photoelectric confinement structure 22c is used to define the light-emitting aperture OA of the heterojunction light-emitting structure 22.

[0041] A composite control layer (not shown) is configured to control the far-field divergence angle of the surface-emitting laser according to the arrangement of the heterojunction light-emitting structures 222. The composite control layer is also configured to select the polarization mode of the emitted laser from the surface-emitting laser.

[0042] Specifically, the composite control layer can include a plurality of control units 42, one control unit 42 is arranged above the light emitting aperture OA of a heterojunction light emitting structure 22 and in contact with the top mirror structure 22d of the heterojunction light emitting structure 22; wherein the plurality of control units 42 of the composite control layer are arranged to satisfy the following conditions:

[0043] The total light output of at least one control unit is greater than the total light output of any other control unit. In this embodiment, the total light output can be understood as the area of the light output region, which refers to the region that can transmit laser of a predetermined wavelength. For example Figure 3a In the embodiment, the total light output of the control unit 42a of the heterojunction light emitting structure 222 (the bright green strip pattern in the figure) is greater than the total light output of the control unit 42b of the heterojunction light emitting structure 224 (the bright green strip pattern in the figure); for example, Figure 3b In the embodiment, the total light output of the control unit 42a of the heterojunction light emitting structure 222 (the bright green strip pattern in the figure) is greater than the total light output of the control unit 42b of the heterojunction light emitting structure 224 and the heterojunction light emitting structure 226 (the bright green strip pattern in the figure), and in this embodiment, the total light output of the control unit 42b of the heterojunction light emitting structure 224 and the heterojunction light emitting structure 226 is the same; for example, Figure 3c In the embodiment, the total light output of the control unit 42a of the heterojunction light emitting structure 222 (the bright green strip pattern in the figure) is greater than the total light output of the control unit 42b of the heterojunction light emitting structure 224 and the control unit 42c of the heterojunction light emitting structure 226 (the bright green strip pattern in the figure), and in this embodiment, the total light output of the control unit 42b of the heterojunction light emitting structure 224 is greater than the total light output of the control unit 42b of the heterojunction light emitting structure 226, that is, the light output area of the control unit 42a, the control unit 42b and the control unit 42c in this embodiment gradually decreases; further, the decrease can be equal proportionally, or in the form of equal difference, or irregularly, which is not limited in the present application.

[0044] In the embodiment of the present application, reference can be made to Figures 3a-3bThe regulating unit 42 can include a base layer 22e and a plurality of etching patterns (strip-shaped etching patterns) obtained by partially etching the base layer 22e, and the sum of the areas of the etching patterns is the total light emission amount. In this embodiment, the regulating unit 42 can be regarded as a grating. For the convenience of description and understanding, the regulating unit 42 is taken as a grating in the following embodiments. Alternatively, the etching patterns can also be cylindrical, or frustoconical, or regular polygonal. The base layer 22e can be a semiconductor material (for example, a material in the III-V system, typically a gallium arsenide system or an indium phosphorus system material), or an insulating material (for example, silicon nitride, silicon oxide or aluminum trioxide). In this embodiment, the base layer 22e is multiplexed as an ohmic contact semiconductor layer, and the regulating unit 42 is obtained by partially etching the base layer 22e.

[0045] Advantageously, the general outline of the regulating unit 42 is designed to be similar to the general outline of the light emitting aperture OA. For example Figure 1 , Figures 3a-3c , the light emitting aperture OA is circular, and the outline of the regulating unit 42 is also circular. It can be determined that the outline of the regulating unit 42 here refers to the outer outline of the pattern enclosed by the etching patterns. For example Figures 4a-4d , the light emitting aperture OA is circular, the outline of the regulating unit 42a is elliptical, and the outlines of the regulating units 42b and 42c are circular. It can be understood that based on the same inventive concept, the outline of the regulating unit 42 can also be designed to be other advantageous shapes, and the outline of the light emitting aperture OA can also be designed to be other advantageous shapes, for example, regular polygonal, diamond-shaped, spindle-shaped, etc. This design is advantageous for mode control and polarization suppression.

[0046] In this embodiment, refer to Figure 1 and Figure 2 , the bottom mirror structure 22a and the top mirror structure 22d define the resonant cavity structure of the surface emitting laser of the application, that is, the area between the bottom mirror structure 22a and the top mirror structure 22d is the resonant cavity. The resonant cavity is used to generate a standing wave, which is a wave formed by two coherent waves propagating in opposite directions on the same straight line and superimposed on each other. Specifically, when the phases of the two waves are the same, their amplitudes are added to form a wave crest (i.e., a wave peak). When the phases of the two waves are opposite, their amplitudes are subtracted to form a wave node (i.e., a wave trough). Therefore, the positions of the wave peaks and wave troughs of the standing wave are fixed.

[0047] In one embodiment, the bottom mirror structure 22a can include a periodic stack of DBR structure, i.e. a plurality of mirrors with a quarter of the lasing wavelength of optical thickness, and the plurality of mirrors are arranged in an alternating high and low refractive index. The top mirror structure 22d also includes a periodic stack of DBR structure, i.e. a plurality of mirrors with a quarter of the lasing wavelength of optical thickness, and the plurality of mirrors are arranged in an alternating high and low refractive index. It can be understood that the DBR structure of the bottom mirror structure 22a and the DBR structure of the top mirror structure 22d can be the same or different in composition, stack period, etc., which is not limited in the present embodiment. The materials of the top mirror structure 22d and the bottom mirror structure 22a can be dielectric materials with electrical insulation, such as silicon nitride, silicon oxide, aluminum oxide or titanium oxide, etc. The materials of the top mirror structure 22d and the bottom mirror structure 22a can also be semiconductor materials, such as GaAs and AlGaAs.

[0048] The material of the substrate 10 includes but is not limited to GaAs, InP, Si, etc. The bottom mirror structure 22a and the top mirror structure 22d can include a film layer with a periodically varying refractive index to achieve high-efficiency reflection or transmission of light in a specific wavelength range. The film layer with a periodically varying refractive index can be composed of semiconductor materials, dielectric materials, metal-dielectric hybrid materials, etc. For example, the bottom mirror structure 22a can be an N-type semiconductor layer, and the top mirror structure 22d can be a P-type semiconductor layer. For another example, the bottom mirror structure 22a can be a P-type semiconductor layer, and the top mirror structure 22d can be an N-type semiconductor layer. Alternatively, the materials of the N-type semiconductor layer and the P-type semiconductor layer can be but not limited to GaAs, AlGaAs, etc., which is not limited herein, as long as the resonance cavity can be limited, it belongs to the protection scope of the present embodiment. Specifically, the resonance cavity structure can further include a photoelectric confinement structure 22c formed in the top mirror structure 22d.

[0049] The active layer 22b can include one active region, two active regions, three active regions, or four active regions. Each active region can be provided with one or more multiple quantum well structures. The multiple quantum well structure is used to generate stimulated radiation photons, and the emitted photons are repeatedly reflected in the resonance cavity defined by the bottom mirror structure 22a and the top mirror structure 22d, and are repeatedly enhanced in the reflection process, so that the final laser with a specific wavelength and sufficient energy is emitted.

[0050] The multi-quantum well structure is where the laser gain amplification occurs, and the center of the multi-quantum well structure can be aligned with the position of the strongest light field to achieve greater amplification. Further, in the case of including multiple multi-quantum well structures, the confinement factor of the multi-quantum well structures in the same light field is within the same predetermined range, that is, the confinement factors of the multi-quantum well structures are maintained at the same level, so that each multi-quantum well structure contributes similarly to the light emission. It can be understood that similar light emission contribution means that the current injection in each multi-quantum well structure is more uniform, which helps to reduce the threshold current of the device, thereby reducing the power consumption of the device and prolonging its service life. Moreover, when each multi-quantum well structure contributes similarly to the light emission, the distribution of carriers in each multi-quantum well structure will be more uniform, which helps to reduce the loss of carrier recombination, thereby improving the overall light emission efficiency of the device.

[0051] Generally, the number of optoelectronic confinement structures 22c is not greater than the number of active layers 22b, for example, can be 2, 3, 4, etc. The optoelectronic confinement structure 22c is used to define the light emission area of the surface emitting laser. Specifically, the optoelectronic confinement structure 22c is located on the side of the corresponding active layer 22b away from the substrate 10 to restrict the flow of current, so that the current only flows in the light emission area defined by the optoelectronic confinement structure 22c, thereby reducing unnecessary energy consumption, and further reducing the threshold current and improving the current density. Moreover, the optoelectronic confinement structure 22c can also confine the light field in the light emission area defined by the optoelectronic confinement structure 22c, reducing the scattering and diffraction of light, thereby optimizing the divergence angle of the device and improving the beam quality. Generally, the optoelectronic confinement structure 22c is arranged at the position of the lowest light field intensity, that is, at the trough of the standing wave, so that it has a smaller confinement factor, thereby helping to reduce the divergence angle of the device.

[0052] The optoelectronic confinement structure 22c can include any one of an air column type optoelectronic confinement structure, an oxidation confinement type optoelectronic confinement structure, an ion implantation type optoelectronic confinement structure, and a tunnel junction type optoelectronic confinement structure. Among them, the air column type optoelectronic confinement structure realizes the confinement of current and light through an air column, which is a hollow structure formed by dry etching technology, and has a lower refractive index than the surrounding semiconductor material, thereby effectively confining the light in the central region. The ion implantation type optoelectronic confinement structure changes the electrical properties of the semiconductor material by implanting ions into it, forming a high resistance region that can restrict the flow of current, thereby indirectly restricting the light generation area.

[0053] In one embodiment, the oxide-limited photoelectric confinement structure includes an unoxidized region of AlGaAs material with a high Al content and an oxidized region of aluminum oxide material. The oxidized region is located outside the unoxidized region, and the unoxidized region forms the light-emitting region for effective current injection. The semiconductor layer of the unoxidized region in the photoelectric confinement structure 22c can be understood as an opening, which defines the light-emitting region of the surface-emitting laser. When current enters, it can only flow to the active layer 22b through the opening in the photoelectric confinement structure 22c, thereby confining the current injection path and optical mode field. Furthermore, the high-aluminum-content AlGaAs layer can be converted to aluminum oxide through a selective oxidation process to form the outer unoxidized region.

[0054] In one embodiment, the tunnel junction optoelectronic confinement structure includes at least one highly doped N-type structure layer and at least one highly doped P-type structure layer. Specifically, a potential barrier is formed between the highly doped N-type structure layer and the highly doped P-type structure layer, allowing electrons to tunnel through the barrier, thereby achieving lateral confinement of the current. In one embodiment, the materials chosen for the N-type and P-type structure layers are Al. x Ga 1-x As, the doping concentration of the N-type and P-type structural layers is greater than 1e 18 cm -3 , where 0≤x≤1.

[0055] Further reading is available. Figures 1-2 In addition to the aforementioned substrate 10, bottom reflector structure 22a, active layer 22b, photoelectric confinement structure 22c, top reflector structure 22d, and base layer 22e, the surface-emitting laser 1 may also include an ohmic contact metal layer 22f, a passivation layer 22h, a metal via 22g, a metal interconnect layer 32, and pads 34. The ohmic contact metal layer 22f can be a P-type ohmic contact metal layer, the passivation layer 22h can be multilayered, and the metal via 22g electrically connects the metal interconnect layer 32 and the ohmic contact metal layer 22f by penetrating the passivation layer 22h. The pads 34 are disposed on the metal interconnect layer 32 and can be arranged as P-type pads connected to the positive electrode. Furthermore, a metal layer (not shown), also known as back gold, can be disposed below the substrate 10 to provide another type of carrier injection. When the pads 34 are P-type pads, the back gold can be arranged as N-type metal.

[0056] Please continue reading. Figure 1 The injection current density near the P-type pads and the apertures distributed around the periphery of the device is slightly higher than that at the center. This results in more laser light emitting at the center with a lower divergence angle, thus increasing the overall far-field divergence angle of the device. Therefore, a definite objective of this application is to reduce... Figure 1The far field divergence angle problem of the heterojunction light emitting structure 22 arrangement shown in the figure. Of course, there are other ways to reduce the far field divergence angle with different specific arrangements of the heterojunction light emitting structure 22.

[0057] In one embodiment, several heterojunction light emitting structures 22 of the present application can be arranged in an array, for example, a rectangular array, a radial array, a ring array. Figure 1 For the ring array arrangement, six heterojunction light emitting structures 22 are evenly distributed around one heterojunction light emitting structure 22. The heterojunction light emitting structure in this embodiment is not necessarily a separate heterojunction light emitting structure, and the heterojunction light emitting structures can be partially connected, for example, the layers of the bottom mirror structure 22a are partially shared. The heterojunction light emitting structure 22 can be understood as the aforementioned light emitting aperture OA, i.e. the light emitting hole in the conventional technology. It can be understood that the number and arrangement of the heterojunction light emitting structure 22 are not limited to Figure 1 The skilled in the art can make reasonable extensions on this basis.

[0058] Further, with reference to Figure 3a , 3c , 4a, 4b, for the case of uniform array distribution of a plurality of heterojunction light emitting structures 22, and the total light output of the control unit 42a located at the center of the array is greater than the total light output of all control units 42b, 42c located at the periphery of the array. Figure 3a , 4a , in the embodiment of 4b, the total light output of each control unit 42 located at the periphery of the array is the same. In these figures, the total light output of the control unit 42a is greater than the total light output of the control unit 42b adjacent to it. In this way, the far field divergence angle of the device can be reduced, because the divergence angle at the center is large, and the divergence angle around is small, and the overall far field divergence angle after beam combination will be smaller. Figure 3c In the embodiment, among the control units located at the periphery of the array, the total light output of at least some control units is different from the total light output of the remaining control units, for example, the total light output of the control unit 42b is greater than the total light output of the control unit 42c. Further, it can be achieved by adjusting the two-dimensional size of the etching pattern in the control unit 42, for example, by adjusting the length or width or diameter. It can also be achieved by adjusting the number of the smallest etching units in the etching pattern, for example, by increasing or decreasing the number of strip-shaped etching channels to achieve different total light outputs. Further, the total light output can also be adjusted by adjusting the duty cycle, etching depth, etc. of the control unit 42, which is not limited by the present application.

[0059] In one embodiment, the plurality of heterojunction light emitting structures 22 are arranged in an array, and the total light output of each regulating unit 42 can be designed to gradually decrease from the center to the periphery of the array. Specifically, the total light output of each regulating unit 42 can be gradually decreased by adjusting the two-dimensional size (length, width, diameter) of the etching pattern. Specifically, as shown in FIGS. 3c, 4b and 4d, the total light output of each regulating unit 42 can be gradually decreased by adjusting the length (L) of the etching pattern in the regulating unit 42. As shown in FIGS. 3c, 4b and 4d, the total light output of each regulating unit 42 can also be gradually decreased by adjusting the width (W) of the etching pattern in the regulating unit 42. As shown in FIGS. 3c, 4b and 4d, the total light output of each regulating unit 42 can also be gradually decreased by adjusting the number of the smallest etching units in the etching pattern, for example, by increasing or decreasing the number of strip-shaped etching channels to increase the total light output. Further, the total light output of each regulating unit 42 can also be adjusted by adjusting the duty cycle, etching depth, etc. of the regulating unit 42, which is not limited by the present application. Figures 3a-4d Figure 3a 3b Figure 4a Figure 4c

[0060] In one embodiment, the total light output of at least one side of the same regulating unit 22 is greater than that of the other side. Specifically, the heterojunction light emitting structure located at the center of the array is referred to as the first heterojunction light emitting structure, the two heterojunction light emitting structures adjacent to the first heterojunction light emitting structure are referred to as the second heterojunction light emitting structure and the third heterojunction light emitting structure, respectively. The regulating unit located above the first heterojunction light emitting structure is referred to as the first regulating unit, the regulating unit located above the second heterojunction light emitting structure is referred to as the second regulating unit, and the regulating unit located above the third heterojunction light emitting structure is referred to as the third regulating unit. The distance between the first heterojunction light emitting structure and the second heterojunction light emitting structure is referred to as the first distance, and the distance between the first heterojunction light emitting structure and the third heterojunction light emitting structure is referred to as the second distance. The first distance is less than the second distance. The total light output of the side of the first regulating unit close to the second regulating unit is less than that of the side of the first regulating unit close to the third regulating unit.

[0061] Specifically, as shown in FIGS. 3c, 4b and 4d, the total light output of each regulating unit 42 can be gradually decreased by adjusting the length (L) of the etching pattern in the regulating unit 42. As shown in FIGS. 3c, 4b and 4d, the total light output of each regulating unit 42 can also be gradually decreased by adjusting the width (W) of the etching pattern in the regulating unit 42. As shown in FIGS. 3c, 4b and 4d, the total light output of each regulating unit 42 can also be gradually decreased by adjusting the number of the smallest etching units in the etching pattern, for example, by increasing or decreasing the number of strip-shaped etching channels to increase the total light output. Further, the total light output of each regulating unit 42 can also be adjusted by adjusting the duty cycle, etching depth, etc. of the regulating unit 42, which is not limited by the present application. Figure 3b 4c Figure 3b Figure 4c ​​​​​​​​For the case that the total light output of the regulating unit 42a (which can be understood as the first regulating unit) at the center position of the device is greater than the total light output of the left and right or upper and lower adjacent regulating units 42b (which can be understood as the second regulating unit and the third regulating unit), and the total light output of the left regulating unit 42b and the upper regulating unit 42b is the same but the distance is different, in this embodiment, the distance between the heterojunction light emitting structure 222 (which can be understood as the first heterojunction light emitting structure) and the heterojunction light emitting structure 226 (which can be understood as the second heterojunction light emitting structure) is recorded as the first distance H1, and the distance between the heterojunction light emitting structure 222 and the heterojunction light emitting structure 224 (which can be understood as the third heterojunction light emitting structure) is recorded as the second distance H2, H2>H1, in this case, the heterojunction light emitting structure 226 closer to the heterojunction light emitting structure 222 at the center position contributes more to reducing the overall far-field divergence angle of the device, therefore, the light emitting area of the heterojunction light emitting structure 222 on the side close to the heterojunction light emitting structure 226 can be designed to be relatively smaller than the light emitting area on the other side, so that more light is emitted from the other side, balancing the overall far-field divergence angle. For example, the light emitting area of the regulating unit 42a on the side close to the heterojunction light emitting structure 224 in FIG. 1B is set to be greater than the light emitting area of the regulating unit 42a on the side close to the heterojunction light emitting structure 226, and the light emitting area of the regulating unit 42a on the side close to the heterojunction light emitting structure 224 in FIG. 1C is set to be greater than the light emitting area of the regulating unit 42a on the side close to the heterojunction light emitting structure 226. Figure 3b Figure 4c Further, in this example, the asymmetric light emitting area distribution is mainly realized by adjusting the length of the regulating unit 42a.

[0062] Further, Figure 4d For the case opposite to the definition of H1 and H2 in FIGS. 1B and 1C, Figure 3b Figure 4c For the case opposite to the definition of H1 and H2 in FIGS. 1B and 1C, Figure 4d In this case, the light emitting area of the regulating unit 42a on the side close to the heterojunction light emitting structure 226 is set to be smaller than the light emitting area of the regulating unit 42a on the side close to the heterojunction light emitting structure 224; further, in this example, the asymmetric light emitting area distribution is mainly realized by adjusting the length of the regulating unit 42a.

[0063] It can be understood that although the present application describes the distance H2>H1 and the light emitting area on one side of the regulating unit 42 is greater than the light emitting area on the other side (H2>H1, Figure 3b Figure 4c and​​​Figure 4d ) special circumstances, but can be sure, the light output of the regulatory unit 42 total sum of regular changes, heterojunction light emitting structure 22 uniform distribution, more conducive to the current uniform distribution and overall far field divergence angle control, and may be beneficial to the mode control and polarization suppression effect enhancement.

[0064] Suitable reduction of the edge position of the light output of the regulatory unit of the total sum, can effectively reduce the current injection due to uneven chip level far field divergence angle increase and other problems. And enlarge the center position of the light output of the regulatory unit of the total sum, can make more light through the light hole, so as not to lose too much light intensity, and because the current density of the center position of the light hole OA is lower than that of the peripheral light hole OA, therefore, the far field divergence angle will not be too much. Ultimately, it can achieve the purpose of reducing the far field divergence angle at the cost of less power.

[0065] Thanks to the light output of the regulatory unit 42 total sum of regulation, combined with the divergence angle control, the overall light emission angle of the device can be adjusted. For example, by controlling Figure 1 The sum of the light output of all peripheral heterojunction light emitting structures in the left part of the middle is greater than the sum of the light output of all peripheral heterojunction light emitting structures in the right part, so that the overall light divergence angle is deflected to the right, so that it can be applied to some special occasions (for example, emitting at a certain angle compared with some reference, so as to save some light deflection elements). Similarly, other reasonable divergence angle deflection methods should also be included, and this application does not make detailed description.

[0066] In one embodiment, the preparation method of the surface emitting laser in this embodiment can generally include epitaxial growth, MESA trench etching, wet oxidation, deep trench etching, deep trench ion implantation, regulatory unit etching, passivation layer deposition, conductive metal making and the like. Among them, epitaxial growth, MESA trench etching, wet oxidation, deep trench etching, deep trench ion implantation, passivation layer deposition and conductive metal can be understood by referring to the existing surface emitting laser process. This embodiment does not have special improvement on these steps. The key improvement of this application is in the step of making regulatory unit etching.

[0067] Further, the regulatory unit 42 of different heterojunction light emitting structures 22 can be prepared by using different masks.

[0068] It should be understood that although the steps in the flowcharts of the embodiments are shown in a certain order, the steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, the steps are not necessarily executed in strict order, and the steps can be executed in other orders. Moreover, at least some of the steps in the embodiments can include multiple sub-steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution order of the sub-steps or stages is not necessarily sequential, but can be alternated or interleaved with at least part of other steps or sub-steps or stages of other steps.

[0069] In a second aspect, the application also provides a laser radar, comprising a transmitting assembly and a receiving assembly, wherein the transmitting assembly is the surface-emitting laser as described in any of the preceding embodiments.

[0070] In summary, the surface-emitting laser and the laser radar provided by the application can adjust the far-field divergence angle of the device by adjusting the total light output of the control units in the composite control layer, and can also select the laser emission of a preset mode due to the polarization selection characteristic of the grating. Specifically, the greater the total light output of the control units, the higher the light intensity of the emitted light, and the higher the light intensity, the greater the divergence angle. When the light output area of the control units is relatively small, the light intensity of the emitted light is low, and therefore only laser with a small divergence angle can be emitted. Due to the current injection path, the current density at the tip of the light-emitting aperture is higher than the current density at the center of the light-emitting aperture, and therefore the light intensity at the tip of the light-emitting aperture is higher than the light intensity at the center of the light-emitting aperture. Thus, by adjusting the total light output of the control units above different light-emitting apertures according to the actual needs of the device and the above principle, the far-field divergence angle can be adjusted. For example, when the total light output of the control units at the center of the device is maximized and the total light output of the control units around the center is unchanged, the far-field divergence angle can be reduced. For another example, when the total light output of some of the control units around the center of the device is adjusted and the total light output of the remaining control units is unchanged, the far-field divergence angle can also be deflected.

[0071] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but it should be considered that any combination of the technical features is within the scope of the present disclosure as long as the combination does not result in contradictions.

[0072] The above-described embodiments only express several implementation manners of the application, the description is more specific and detailed, but it cannot be understood as the limitation of the utility model patent scope. It should be pointed out that for ordinary skilled in the art, without departing from the application embodiment concept, several modifications and improvements can be made, which all belong to the protection scope of the application. Therefore, the protection scope of the application patent should be subject to the appended claims.

Claims

1. A surface emitting laser, characterized by, The surface-emitting laser comprises: a substrate; a heterojunction light-emitting array arranged on the substrate, the heterojunction light-emitting array comprising a plurality of heterojunction light-emitting structures; and a composite control layer arranged above the heterojunction light-emitting array; wherein the composite control layer is configured to control the far-field divergence angle of the surface-emitting laser according to the arrangement position relationship of each of the heterojunction light-emitting structures, and the composite control layer is further configured to select the polarization mode of the emitted laser of the surface-emitting laser. The heterojunction light-emitting structure comprises a bottom mirror structure, an active layer, a photoelectric confinement structure, and a top mirror structure, the bottom mirror structure and the top mirror structure defining a resonant cavity for emitting laser of a predetermined wavelength, and the photoelectric confinement structure is used to define the light-emitting aperture of the heterojunction light-emitting structure; the composite control layer is arranged on the top mirror structure; and / or 2. The surface emitting laser of claim 1, wherein The bottom mirror structure is an N-type mirror structure, and the top mirror structure is a P-type mirror structure; and / or The photoelectric confinement structure comprises any one of an air column type photoelectric confinement structure, an oxidation confinement type photoelectric confinement structure, an ion implantation type photoelectric confinement structure, and a tunnel junction type photoelectric confinement structure. The composite control layer comprises a plurality of control units, one control unit being arranged above the light-emitting aperture of one heterojunction light-emitting structure, and the control unit is configured to control the light-emission amount and the polarization mode of the heterojunction light-emitting structure; and / or 3. The surface emitting laser of claim 2, wherein, The light-emission amount sum of at least one control unit is greater than the light-emission amount sum of any other control unit; and / or The general outline of the control unit is similar to the general outline of the light-emitting aperture. The control unit comprises a base layer and a plurality of etching patterns obtained by partially etching the base layer, and the sum of the areas of each etching pattern is the light-emission amount sum.

4. The surface emitting laser of claim 3, wherein, In the direction from the center to the periphery of the heterojunction light-emitting array, the light-emission amount sum of each control unit gradually decreases; and / or 5. The surface emitting laser of claim 4, wherein, The gradual decrease of the light-emission amount sum of each control unit is achieved by adjusting the two-dimensional size of the etching pattern. The light-emission amount sum of the control unit located at the center of the heterojunction light-emitting array is greater than the light-emission amount sum of all the control units located at the periphery of the heterojunction light-emitting array; and / or 6. The surface emitting laser of claim 4, wherein, The light-emission amount sum of each control unit located at the periphery of the heterojunction light-emitting array is the same; and / or Among the control units located at the periphery of the heterojunction light-emitting array, the light-emission amount sum of at least some control units is different from the light-emission amount sum of the remaining control units. The gradual decrease of the light-emission amount sum of the control unit located at the center of the heterojunction light-emitting array is greater than the light-emission amount sum of all the control units located at the periphery of the heterojunction light-emitting array is achieved by adjusting the two-dimensional size of the etching pattern.

7. The surface emitting laser of claim 6, wherein, The spacing between each of the heterojunction light-emitting structures is not completely the same; and / or 8. The surface emitting laser of claim 1, wherein, The spacing between the heterojunction light-emitting structure located at the center of the heterojunction light-emitting array and any two heterojunction light-emitting structures adjacent thereto is different. In the same control unit, the light-emission amount of at least one side is greater than the light-emission amount of the other side opposite to the one side.

9. The surface emitting laser of claim 8, wherein, The surface-emitting laser comprises a transmitting component and a receiving component, and the transmitting component adopts the surface-emitting laser according to any one of claims 1-9.

10. A lidar, comprising: ​

Images