Vertical cavity surface emitting laser, light source and laser radar

Abstract

The invention discloses a vertical-cavity surface-emitting laser, a light source and a laser radar, the vertical-cavity surface-emitting laser comprises an epitaxial layer and a grating layer, the epitaxial layer comprises a substrate, and a bottom mirror structure, an active layer, a photoelectric limiting layer and a top mirror structure which are sequentially arranged on the substrate, the photoelectric limiting layer is used for limiting a light-emitting area of the vertical-cavity surface-emitting laser; the grating layer is arranged on the epitaxial layer and comprises a polarization suppression area and a mode suppression area arranged around the polarization suppression area, and the polarization suppression area is located in the light emitting area; wherein the boundary of the polarization suppression area and the mode suppression area is overlapped with the light emitting area, and the overlapped part at least partially covers the edge of the light emitting area. According to the scheme provided by the invention, the far-field divergence angle does not need to be reduced on the premise of sacrificing the optical power in order to pursue a small far-field divergence angle; the number of etching channels does not need to be increased in order to compensate for the loss of optical power.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a vertical cavity surface emitting laser, a light source and a laser radar. Background Art

[0002] Vertical-Cavity Surface-Emitting Laser (VCSEL) is a unique semiconductor laser. VCSEL is based on population inversion and stimulated emission. By injecting current or optical pumping, the electrons in the active area transition from low energy levels to high energy levels, forming a population inversion distribution. At this time, the electrons transition from high energy levels back to low energy levels, releasing photons, which are reflected in the resonant cavity, continuously stimulating stimulated emission and achieving light amplification. At the same time, the length of the resonant cavity determines that only light of a specific wavelength can form a stable oscillation mode and achieve single-mode or multi-mode output.

[0003] VCSEL has many advantages. It is easy to test and manufacture, can be directly tested on the chip, can reduce costs and facilitate large-scale integration; the beam quality is good, and the coupling efficiency with the optical fiber is high; the threshold current is low, and the power consumption is small; the modulation frequency is high, which can meet the needs of high-speed data transmission; the working stability is good, and the wavelength is stable.

[0004] However, in VCSEL design, the far-field divergence angle and optical power are like the two ends of a seesaw, but these two indicators are very important for VCSEL. In order to pursue a small far-field divergence angle, both the Epi end and the chip design end of VCSEL sacrifice optical power to reduce the far-field divergence angle; correspondingly, in order to compensate for the loss of optical power, the number of light-emitting holes on the chip has to be increased. However, the increase in light-emitting holes will bring about chip size, heat generation, and uneven injection current, which will increase the loss of unit optical power of the light-emitting holes. The uneven current injection will also lead to an increase in the far-field divergence angle. When VCSEL introduces polarization requirements, the output optical power will further attenuate the intensity of the light due to the polarization grating. In the end, the device will reduce the far-field divergence angle at the expense of a significant decrease in light intensity or photoelectric conversion efficiency.

[0005] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0006] The main purpose of the present invention is to provide a vertical cavity surface emitting laser, a light source and a laser radar, aiming to solve the technical problems in the prior art that the vertical cavity surface emitting laser reduces the far-field divergence angle at the expense of optical power in order to pursue a small far-field divergence angle; or increases the number of etched paths in order to compensate for the loss of optical power.

[0007] To achieve the above object, the present invention provides a vertical cavity surface emitting laser, the vertical cavity surface emitting laser comprising: An epitaxial layer, comprising a substrate, and a bottom mirror structure, an active layer, a photoelectric limiting layer and a top mirror structure sequentially arranged on the substrate, wherein the photoelectric limiting layer is used to define a light emitting area of ​​the vertical cavity surface emitting laser; a grating layer, disposed on the epitaxial layer, the grating layer comprising a polarization suppression region and a mode suppression region disposed around the polarization suppression region, the polarization suppression region being located in the light emitting region; The boundary between the polarization suppression region and the mode suppression region overlaps with the light-emitting region, and the overlapping portion at least partially covers the edge of the light-emitting region.

[0008] Optionally, in the vertical cavity surface emitting laser, the polarization suppression region is provided with a grating structure; The grating structure includes a contact layer and a plurality of etched paths obtained by partially etching the contact layer.

[0009] Optionally, in the vertical cavity surface emitting laser, the contact layer is a part of the top mirror structure.

[0010] Optionally, in the vertical cavity surface emitting laser, the contact layer is a layer of semiconductor material additionally grown on the top mirror structure.

[0011] Optionally, in the vertical cavity surface emitting laser, the etching depth of the etching track is an integer multiple of one quarter of the working wavelength; and / or The thickness of the contact layer remaining after etching is an integer multiple of one quarter of the working wavelength.

[0012] Optionally, in the vertical cavity surface emitting laser, ends of at least part of the etched paths are spaced a preset distance from edges of the light emitting region.

[0013] Optionally, ends of some of the etched paths are spaced from the edge of the light-emitting area by a first preset distance, and ends of the remaining parts of the etched paths are spaced from the edge of the light-emitting area by a second preset distance; wherein the first preset distance is not equal to the second preset distance.

[0014] Optionally, in the vertical cavity surface emitting laser, the mode suppression region includes a gallium arsenide layer, and a thickness of the gallium arsenide layer is an integer multiple of one quarter of an operating wavelength.

[0015] Optionally, in the vertical cavity surface emitting laser, the gallium arsenide layer has a thickness of 200-300 nm.

[0016] To achieve the above-mentioned objectives, the present invention provides a light source for a laser radar system, wherein the light source for the laser radar system comprises at least one laser array; the laser array comprises a plurality of the above-mentioned vertical cavity surface emitting lasers; the laser array is a regularly arranged array, or a randomly arranged array, or an array with multiple addressable sub-arrays.

[0017] To achieve the above-mentioned object, the present invention provides a laser radar, which includes a transmitting component and a receiving component, and the transmitting component adopts the above-mentioned light source for the laser radar system.

[0018] The present invention has at least the following beneficial effects: The vertical cavity surface emitting laser provided by the present invention, the epitaxial layer includes a substrate, and a bottom mirror structure, an active layer, a photoelectric limiting layer and a top mirror structure sequentially arranged on the substrate, the photoelectric limiting layer is used to limit the light-emitting area of ​​the vertical cavity surface emitting laser; the grating layer is arranged on the epitaxial layer, the grating layer includes a polarization suppression area and a mode suppression area arranged around the polarization suppression area, the polarization suppression area is located in the light-emitting area; wherein the boundary between the polarization suppression area and the mode suppression area overlaps with the light-emitting area and the overlapping part at least partially covers the edge of the light-emitting area. In this way, there is no need to reduce the far-field divergence angle at the expense of optical power in order to pursue a small far-field divergence angle; similarly, there is no need to consider increasing the number of etching paths in order to compensate for the loss of optical power.

[0019] Furthermore, the polarization suppression region is located within the light-emitting region, and the boundary between the polarization suppression region and the mode suppression region overlaps with the light-emitting region, and the overlapping portion at least partially covers the edge of the light-emitting region, so as to suppress the excitation of high-order modes at the edge of the light-emitting region through the mode suppression region. In this way, the high-order modes generated near the edge of the light-emitting region will be limited by the mode suppression region and will be suppressed, but the low-order modes with a smaller far-field divergence angle at the center of the light-emitting region will pass through the polarization suppression region, thereby achieving the function of suppressing the far-field divergence angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the relative relationship between the conventional polarization suppression area and the light emitting area; Figure 2 A relative relationship between the polarization suppression region and the light emitting region in the vertical cavity surface emitting laser provided by the present invention; Figure 3 A schematic diagram of an embodiment of a vertical cavity surface emitting laser provided by the present invention; Figure 4 A schematic diagram of another embodiment of a vertical cavity surface emitting laser provided by the present invention; Figure 5 The present invention provides a relative relationship between the etched path and the edge of the light emitting area in the vertical cavity surface emitting laser.

[0021] Prior art reference numerals: 1411'-edge of the light emitting area, 181a'-etching track.

[0022] Reference numerals of the present invention: 100-vertical cavity surface emitting laser, 110-substrate, 120-bottom mirror structure, 130-active layer, 140-photoelectric confinement layer, 141-light emitting region, 1411-edge of the light emitting region, 150-top mirror structure, 160-top metal layer, 170-passivation layer, 180-grating layer, 181-polarization suppression region, 181a-etched path, 182-mode suppression region, 183-boundary between the polarization suppression region and the mode suppression region.

[0023] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0025] In the embodiments of the present invention, the term "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent three situations: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0026] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0027] In the embodiments of the present invention, the term "plurality" refers to two or more than two, and other quantifiers are similar.

[0028] In the present invention, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity directions; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above-mentioned directional words are not used to limit the present invention.

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. However, it can be understood by those skilled in the art that in the embodiments of the present invention, many technical details are proposed in order to enable the reader to better understand the present invention. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present invention can also be implemented. The division of the following embodiments is for the convenience of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined and referenced with each other under the premise of no contradiction.

[0030] The far-field divergence angle and optical power in VCSEL are like the two ends of a seesaw, but these two indicators are very important for VCSEL. In order to pursue a small far-field divergence angle, both the Epi end and the chip design end of VCSEL sacrifice optical power to reduce the far-field divergence angle; correspondingly, in order to compensate for the loss of optical power, the number of light-emitting holes on the chip has to be increased. However, the increase in light-emitting holes will bring about chip size, heat generation, and uneven injection current, which will increase the loss of unit optical power of the light-emitting holes. The uneven current injection will also lead to an increase in the far-field divergence angle. When VCSEL introduces polarization requirements, the output optical power will further attenuate the intensity of the light due to the polarization grating. In the end, the device will reduce the far-field divergence angle at the expense of a significant decrease in light intensity or photoelectric conversion efficiency.

[0031] Figure 1 The diagram shows the relative relationship between the conventional polarization suppression area and the light emitting area. Figure 1 The boundary between the middle polarization suppression region and the mode suppression region is located outside the light emitting region, that is, beyond the edge 1411' of the light emitting region. At this time, in order to pursue a small far-field divergence angle, the far-field divergence angle is usually reduced at the expense of optical power; similarly, in order to compensate for the loss of optical power, the number of etched paths 181a' in the polarization suppression region may be increased.

[0032] Figure 2 The diagram shows the relative relationship between the polarization suppression region and the light emitting region in the vertical cavity surface emitting laser provided by the present invention. Figure 2A portion of the polarization suppression region 181 is located in the light emitting region 141, that is, at this time, the boundary 183 between the polarization suppression region 181 and the mode suppression region 182 overlaps with the light emitting region 141, and the overlapping portion at least partially covers the edge of the light emitting region 141, so that the high-order mode excitation at the edge 1411 of the light emitting region 141 can be suppressed through the edge of the mode suppression region 182. Therefore, the solution of the present invention does not need to reduce the far-field divergence angle at the expense of optical power in order to pursue a small far-field divergence angle; similarly, there is no need to consider increasing the number of etching paths 181a in order to compensate for the loss of optical power.

[0033] More specifically, Figure 3 and Figure 4 The schematic diagram of the vertical cavity surface emitting laser embodiment provided by the present invention is shown. Figure 3 and Figure 4 The present invention provides a vertical cavity surface emitting laser 100, which may include an epitaxial layer and a grating layer 180. The epitaxial layer may include, but is not limited to, a substrate 110, and a bottom mirror structure 120, an active layer 130, an optoelectronic confinement layer 140, and a top mirror structure 150 sequentially disposed on the substrate 110.

[0034] In the vertical cavity surface emitting laser 100 provided by the present invention, the photoelectric limiting layer 140 is used to limit the light emitting area 141 of the vertical cavity surface emitting laser 100; the grating layer 180 is arranged on the epitaxial layer, and the grating layer 180 includes a polarization suppression area 181 and a mode suppression area 182 arranged around the polarization suppression area 181, and the polarization suppression area 181 is located in the light emitting area 141; the boundary 183 between the polarization suppression area 181 and the mode suppression area 182 overlaps with the light emitting area 141, and the overlapping part at least partially covers the edge of the light emitting area 141. In this way, the high-order mode excitation of the edge 1411 of the light emitting area 141 can be suppressed through the edge of the mode suppression area 182, and there is no need to reduce the far-field divergence angle at the expense of optical power in order to pursue a small far-field divergence angle; similarly, there is no need to consider increasing the number of etching paths 181a in order to compensate for the loss of optical power.

[0035] More specifically, the substrate 110 is located at the bottom of the vertical cavity surface emitting laser 100. Typically, the substrate 110 includes a support material, and one or more layers or features of the vertical cavity surface emitting laser 100 are grown or manufactured on or in the support material. In some embodiments, the substrate 110 includes an n-type material. In some other embodiments, the substrate 110 includes a semi-insulating type of material. When the vertical cavity surface emitting laser 100 includes one or more bottom emitters, a semi-insulating type of material can be used to reduce optical absorption from the substrate 110. In some embodiments, the substrate 110 can also include a semiconductor material, such as gallium arsenide (GaAs), indium phosphide (InP), or another type of semiconductor material.

[0036] The bottom mirror structure 120 is disposed on the substrate 110. The bottom mirror structure 120 is a bottom emitter of an optical resonator of the vertical cavity surface emitting laser 100. The bottom mirror structure 120 may include a DBR, a dielectric mirror, etc. In some embodiments, the bottom mirror structure 120 is formed of an n-type material. In some other embodiments, at least a portion of the bottom mirror structure 120 is formed of an n-type material. In this embodiment, the bottom mirror structure 120 uses an n-type distributed Bragg reflector (n-DBR).

[0037] The active layer 130 is disposed on the bottom mirror structure 120. The active layer 130 generally includes a region of one or more quantum wells (MQWs) embedded in a semiconductor material. For example, the active layer 130 may include a GaAs quantum well embedded in AlGaAs. In some other embodiments, the active layer 130 may also be an InGaAs quantum well embedded in GaAs. The material of the active layer 130 may be selected from GaAs / AlGaAs, InGaAsP / InP, etc. For a vertical cavity surface emitting laser 100 with a short wavelength (such as about 850nm), a GaAs / AlGaAs material system is generally used; and for a vertical cavity surface emitting laser 100 with a long wavelength (such as 1310nm, 1550nm), an InGaAsP / InP material system is mostly used.

[0038] The photoelectric confinement layer 140 provides optical and electrical confinement for the vertical cavity surface emitting laser 100. The photoelectric confinement layer 140 is disposed on the active layer 130. In some embodiments, the photoelectric confinement layer 140 is an oxide layer formed by oxidation of one or more epitaxial layers of the vertical cavity surface emitting laser 100. The unoxidized portion in the middle of the photoelectric confinement layer 140 defines a light emitting region 141. The photoelectric confinement layer 140 is used to define the light emitting region 141 of the vertical cavity surface emitting laser 100. Typically, the light emitting region 141 of the photoelectric confinement layer 140 is circular in shape. Of course, in some other embodiments, the light emitting region 141 of the photoelectric confinement layer 140 may also be non-circular in shape. In this embodiment, the light emitting region 141 of the photoelectric confinement layer 140 is circular in shape.

[0039] More specifically, the photovoltaic confinement layer 140 is disposed in the top mirror structure 150 and close to the bottom surface of the top mirror structure 150. The photovoltaic confinement layer 140 is located very close to the active layer 130 in the top mirror structure 150 to confine the injection current of the active layer 130.

[0040] The top mirror structure 150 is a top emitter of the optical resonator of the vertical cavity surface emitting laser 100. The top mirror structure 150 may include a DBR, a dielectric mirror, etc. In some embodiments, the top mirror structure 150 is formed of a p-type material. In some other embodiments, at least a portion of the top mirror structure 150 is formed of an n-type material. In this embodiment, the top mirror structure 150 uses a p-type distributed Bragg reflector (p-DBR). The top mirror structure 150 is disposed on the active layer 130 and the photoelectric confinement layer 140.

[0041] The grating layer 180 is disposed on the epitaxial layer, and includes a polarization suppression region 181 and a mode suppression region 182 disposed around the polarization suppression region 181. The polarization suppression region 181 is located in the light emitting region 141. The boundary 183 between the polarization suppression region 181 and the mode suppression region 182 overlaps with the light emitting region 141, and the overlapping portion at least partially covers the edge of the light emitting region 141. In this way, the high-order mode generated near the edge 1411 of the light emitting region 141 will be limited by the mode suppression region 182 and will be suppressed, but the low-order mode with a smaller far-field divergence angle at the center of the light emitting region 141 will pass through the polarization suppression region 181, thereby playing the function of suppressing the far-field divergence angle.

[0042] Of course, the mode suppression region 182 cannot be too large, otherwise the output optical power will be too small. Therefore, under the condition of ensuring the output optical power, the mode suppression region 182 can be appropriately increased.

[0043] More specifically, the polarization suppression region 181 is provided with a grating structure; the grating structure includes a contact layer and a plurality of etching paths 181a obtained by partially etching the contact layer. The polarization suppression region 181 can be defined by the region formed by connecting the tips of the etching paths 181a in sequence, so the boundary 183 between the polarization suppression region 181 and the mode suppression region 182 can be defined by the edge of the region formed by connecting the tips of the etching paths 181a in sequence. Since the current injection will cause the current density at the edge 1411 of the light-emitting region 141 to be significantly higher than the center of the light-emitting region 141, the high-order mode will also be distributed at the edge 1411 of the light-emitting region 141. In the present invention, the boundary 183 between the polarization suppression region 181 and the mode suppression region 182 overlaps with the light-emitting region 141, and the overlapping portion at least partially covers the edge of the light-emitting region 141, so as to suppress the excitation of the high-order mode at the edge 1411 of the light-emitting region 141 through the edge of the mode suppression region 182.

[0044] The contact layer may also be a part of the top mirror structure 150; in some other embodiments, the contact layer may also be a layer of semiconductor material additionally grown on the top mirror structure 150. The contact layer may be made of gallium arsenide (GaAs); of course, in some other embodiments, the contact layer may also be made of indium phosphide (InP) or another type of semiconductor material.

[0045] Usually, the current density at the edge 1411 of the light-emitting region 141 is higher than the current density in the middle of the light-emitting region 141, that is, the current density of the light-emitting region 141 is larger at the two sides and smaller in the middle. Correspondingly, usually, the far-field divergence angle at the edge 1411 of the light-emitting region 141 is larger and smaller in the middle, that is, the greater the injection current density, the larger the far-field divergence angle. The present invention can limit the light output power of the edge 1411 of the light-emitting area 141 and suppress the high-order mode light emission of the edge 1411 of the light-emitting area 141 by overlapping the boundary 183 of the polarization suppression area 181 and the mode suppression area 182 with the light-emitting area 141 and the overlapping portion at least partially covers the edge of the light-emitting area 141, that is, by overlapping the boundary 183 of the polarization suppression area 181 and the mode suppression area 182 with the light-emitting area 141 and the overlapping portion at least partially covers the edge of the light-emitting area 141, the light output power of the edge 1411 of the light-emitting area 141 can be significantly reduced compared with the conventional one, thereby suppressing the high-order mode light emission with a larger far-field divergence angle caused by the high current density at the edge 1411 of the light-emitting area 141, thereby achieving the purpose of reducing the far-field divergence angle of the device.

[0046] More specifically, at least part of the ends of the etching paths 181a are spaced apart from the edge 1411 of the light emitting region 141 by a preset distance; further, the ends of all the etching paths 181a can be spaced apart from the edge 1411 of the light emitting region 141 by the same preset distance; or Figure 5 As shown, the end of a part of the etching path 181a can also be set to the same first preset distance from the edge 1411 of the light-emitting area 141, and the end of the remaining part of the etching path 181a can be set to the edge 1411 of the light-emitting area 141. The first preset distance is different from the second preset distance (for example, the first preset distance is 0.5-1μm, and the second preset distance is 0μm). In this way, the shape of the light spot can be controlled by adjusting the length of different etching paths 181a. In this way, it can be ensured that the boundary 183 between the polarization suppression area 181 and the mode suppression area 182 overlaps with the light-emitting area 141, and the overlapping part at least partially covers the edge of the light-emitting area 141, and the polarization suppression effect and mode suppression effect of the designed grating structure can be optimized. Of course, in some other embodiments, according to the distribution of high-order modes in the actual simulation process, the ends of at least most of the etching paths 181a can be separated from the edge 1411 of the light-emitting area 141 by a preset distance, and the ends of some etching paths 181a can be set at the edge 1411 of the light-emitting area 141 to achieve the best high-order mode suppression effect.

[0047] It should be noted that, since the overall light output power needs to be guaranteed, the preset distance between the end of the etched path 181a and the edge 1411 of the light-emitting region 141 cannot be too large, that is, the end of the etched path 181a is spaced from the edge 1411 of the light-emitting region 141 by a preset distance without affecting the overall light output power. More specifically, the light-emitting region 141 has a region u1 (at the edge 1411 of the light-emitting region 141) with a significantly higher current density, and the diameter of the light-emitting region 141 is D. Then the region u1 is the region between the region with a diameter d at the light-emitting region 141 and the edge 1411 of the light-emitting region 141, that is, the region between the diameter d and the diameter D. That is, the boundary 183 between the polarization suppression region 181 and the mode suppression region 182 can be located in the region u1, so that the output light power can be guaranteed while reducing the far-field divergence angle. At this time, the far-field divergence angle can be effectively reduced without loss or loss of the output light power.

[0048] The "significantly larger current density" mentioned in the present invention may be determined according to actual needs, specifically according to the working conditions of the device and the size of the light-emitting region 141. For example, when the size of the light-emitting region 141 is larger, the size of the corresponding region u1 will be larger.

[0049] The boundary 183 between the polarization suppression region 181 and the mode suppression region 182 may be in a regular shape or an irregular shape. This application does not make any further limitation on this, and those skilled in the art may make adaptive adjustments based on the concept of this application.

[0050] In addition, the output optical power can be emitted through the etched path 181a of the polarization suppression region 181. The polarization suppression region 181 has polarization, which can make the emitted light linearly polarized; and the mode suppression region 182 has the function of suppressing the lasing of high-order modes, which is mainly due to the etching depth of the etched path 181a being an integer multiple of one quarter of the working wavelength; or the thickness of the contact layer remaining after etching is an integer multiple of one quarter of the working wavelength. In this embodiment, for a vertical cavity surface emitting laser with a wavelength of 905nm, the etching depth of the etched path 181a can be 55-75nm (including the end). Further, the etching depth of the etched path 181a can be 55nm-60nm (including the end); or, the etching depth of the etched path 181a can be 61nm-65nm (including the end); or, the etching depth of the etched path 181a can be 66nm-70nm (including the end); or, the etching depth of the etched path 181a can also be 71nm-75nm (including the end). Furthermore, the etching depth of the etching path 181a can be 55nm-58nm (including the end); or, the etching depth of the etching path 181a can be 59nm-61nm (including the end); or, the etching depth of the etching path 181a can also be 62nm-65nm (including the end); or, the etching depth of the etching path 181a can also be 66nm-69nm (including the end); or, the etching depth of the etching path 181a can also be 70nm-73nm (including the end); or, the etching depth of the etching path 181a can also be 74nm-75nm (including the end). It should be understood that the etching depth of the etching path 181a can be determined by the working wavelength, and the present application does not limit this.

[0051] More specifically, the mode suppression region 182 includes a gallium arsenide layer, and the thickness of the gallium arsenide layer is selected to be an integer multiple of one quarter of the working wavelength. Selecting a multiple of one quarter of the working wavelength can achieve a high reflectivity (greater than 90%), which can increase the threshold condition for high-order mode lasing, so that the high-order mode cannot reach the lasing threshold in the mode suppression region 182 and is suppressed, so that the effect of suppressing the lasing of the high-order mode is better. In some other embodiments, the mode suppression region 182 can also use other semiconductor materials with high reflectivity. Since the current density at the edge 1411 of the light-emitting region 141 is significantly higher than that at the center of the light-emitting region 141, in order to further improve the effect of the mode suppression region 182 in suppressing the high-order mode, in some embodiments, the thickness of the gallium arsenide layer is 200-300nm.

[0052] In addition, the vertical cavity surface emitting laser 100 may further include a top metal layer 160, a passivation layer 170, etc. The top metal layer 160 and the passivation layer 170 are taken as examples for further description.

[0053] The top metal layer 160 may be located at the upper end of the vertical cavity surface emitting laser 100. In some embodiments, the top metal layer 160 is formed by a metal and / or alloy stack.

[0054] More specifically, the passivation layer 170 is disposed in the grooves between the top metal layers 160 and covers the etched paths 181a of the grating layer 180. The passivation layer 170 may be, for example, silicon nitride, silicon oxide, or aluminum oxide. Of course, in some other embodiments, the passivation layer 170 may also be a polymer dielectric or other types of insulating materials.

[0055] The present invention also provides a light source for a laser radar system, the light source for the laser radar system includes at least one laser array; the laser array includes a plurality of the above-mentioned vertical cavity surface emitting lasers 100; the laser array is a regularly arranged array, or a randomly arranged array, or an array with multiple addressable sub-arrays. The laser array includes an embodiment of the above-mentioned vertical cavity surface emitting laser 100, and the beneficial effects of the above-mentioned vertical cavity surface emitting laser 100 can also be applied to the laser array, so it will not be described in detail here.

[0056] The present invention also provides a laser radar, which includes a transmitting component and a receiving component, and the transmitting component adopts the above-mentioned light source for the laser radar system. The transmitting component includes an embodiment of the above-mentioned light source for the laser radar system, and the beneficial effects of the above-mentioned light source for the laser radar system can also be applied to the laser radar, so it is not described in detail here.

[0057] In the description of this specification, the description with reference to the terms "this embodiment", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0058] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] Obviously, the embodiments described above are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, ordinary technicians in this field can make other different forms of changes or modifications without creative work, which should fall within the scope of protection of the present invention.

Claims

1. A vertical cavity surface emitting laser, characterized in that: include: An epitaxial layer, comprising a substrate, and a bottom mirror structure, an active layer, a photoelectric limiting layer and a top mirror structure sequentially arranged on the substrate, wherein the photoelectric limiting layer is used to define a light emitting area of ​​the vertical cavity surface emitting laser; a grating layer, disposed on the epitaxial layer, the grating layer comprising a polarization suppression region and a mode suppression region disposed around the polarization suppression region, the polarization suppression region being located in the light emitting region; The boundary between the polarization suppression region and the mode suppression region overlaps with the light-emitting region, and the overlapping portion at least partially covers the edge of the light-emitting region.

2. The vertical cavity surface emitting laser according to claim 1, characterized in that: The polarization suppression region is provided with a grating structure; The grating structure includes a contact layer and a plurality of etched paths obtained by partially etching the contact layer.

3. The vertical cavity surface emitting laser according to claim 2, characterized in that: The contact layer is part of the top mirror structure.

4. The vertical cavity surface emitting laser according to claim 2, characterized in that: The contact layer is a layer of semiconductor material additionally grown on the top mirror structure.

5. The vertical cavity surface emitting laser according to claim 2, characterized in that: The etching depth of the etching track is an integer multiple of one quarter of the working wavelength; and / or The thickness of the contact layer remaining after etching is an integer multiple of one quarter of the working wavelength.

6. The vertical cavity surface emitting laser according to claim 2, characterized in that: At least part of the ends of the etched paths are spaced a preset distance from the edge of the light emitting area.

7. The vertical cavity surface emitting laser according to claim 2, characterized in that: The ends of some of the etched paths are spaced from the edge of the light-emitting area by a first preset distance, and the ends of the remaining parts of the etched paths are spaced from the edge of the light-emitting area by a second preset distance; wherein the first preset distance is not equal to the second preset distance.

8. The vertical cavity surface emitting laser according to claim 1, characterized in that: The mode suppression region comprises a gallium arsenide layer, and the thickness of the gallium arsenide layer is an integer multiple of a quarter of the working wavelength.

9. A light source for a laser radar system, characterized in that: It comprises at least one laser array; the laser array comprises a plurality of vertical cavity surface emitting lasers as described in any one of claims 1 to 8; the laser array is a regularly arranged array, or a randomly arranged array, or an array with a plurality of addressable sub-arrays.

10. A laser radar, characterized in that: It comprises a transmitting component and a receiving component, wherein the transmitting component adopts the light source for the laser radar system as described in claim 9.

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