Surface emitting laser, laser emitting module and laser radar

Abstract

The invention provides a surface emitting laser, a laser emission module and a laser radar. The surface emitting laser comprises a first reflection waveguide, a second reflection waveguide, a light emitting layer and a high-order grating. The first reflection waveguide, the second reflection waveguide and the light-emitting layer are arranged in a stacked mode, and the light-emitting layer is located between the first reflection waveguide and the second reflection waveguide. The high-order grating is located on at least one side of the light-emitting layer in the first direction, and the first direction is perpendicular to the surface of the light-emitting layer. The light-emitting layer comprises a plurality of active layers and at least one tunneling layer which are arranged in a stacked mode, and every two adjacent active layers are connected through the corresponding tunneling layer. The high-order grating is used for coupling light emitted by each active layer in the light-emitting layer, so that the light emitted by the light-emitting layer resonates along a second direction and is emitted along the first direction, and the second direction is a direction parallel to the surface of the light-emitting layer. The surface emitting laser realizes horizontal cavity resonance and surface emitting light, so that the surface emitting laser is relatively low in temperature drift coefficient, relatively high in oblique efficiency, relatively high in light beam quality and relatively high in light emitting power.

Description

Technical Field

[0001] The present application relates to the field of semiconductor laser technology, and in particular to a surface emitting laser, a laser emission module and a laser radar. Background Art

[0002] Medium and short-range laser radar has great application prospects in many fields such as vehicle blind spot compensation, automatic parking, whole house intelligence, smart parks, etc. Semiconductor lasers are the main light source of laser radar. In order to improve the detection distance, resolution and anti-interference of laser radar, and reduce the size and cost of laser radar, semiconductor lasers with high pulse power, low divergence angle and stable wavelength are needed.

[0003] In the related art, edge emitting lasers (EEL) and surface emitting distributed feedback lasers (SE-DFB) are usually used in laser radars. However, the beam quality of edge emitting lasers is poor, and complex shaping optical paths are required, resulting in large size, difficulty in assembly and adjustment, and high manufacturing costs of laser radars. In addition, the temperature drift coefficient of edge emitting lasers is large, requiring filters with large bandwidth, which will result in low signal-to-noise ratio and poor ranging capability of laser radars. Compared with edge emitting lasers, surface emitting distributed feedback lasers have the advantages of high power output, low divergence angle, and low temperature drift coefficient. However, the light-emitting layer of existing surface emitting distributed feedback lasers has only one active layer, the device coupling coefficient is small, and the slope efficiency is low. A higher driving current or a large chip size is required to achieve high peak power output, resulting in greater difficulty in designing the driving circuit.

[0004] Therefore, in order to meet the laser radar's demand for semiconductor lasers, it is urgent to provide a semiconductor laser with low temperature drift coefficient, high slope efficiency and high beam quality. Summary of the invention

[0005] The embodiments of the present application provide a surface emitting laser, a laser emitting module and a laser radar, which are used to provide a semiconductor laser with a low temperature drift coefficient, high slope efficiency and high beam quality to meet the requirements of the laser radar for semiconductor lasers.

[0006] In a first aspect, an embodiment of the present application provides a surface emitting laser, and the surface emitting laser provided by the embodiment of the present application may include: two reflection waveguides, a light emitting layer, and a high-order grating. In the embodiment of the present application, for the convenience of description, the two reflection waveguides in the surface emitting laser are respectively referred to as a first reflection waveguide and a second reflection waveguide. In the following description, the names of the first reflection waveguide and the second reflection waveguide may also be interchangeable.

[0007] The first reflection waveguide, the second reflection waveguide and the light-emitting layer are stacked, and the light-emitting layer is located between the first reflection waveguide and the second reflection waveguide. The first reflection waveguide can be a Bragg reflection waveguide or a total reflection waveguide, and the second reflection waveguide can be a Bragg reflection waveguide or a total reflection waveguide. The high-order grating is located on at least one side of the light-emitting layer along the first direction, wherein the first direction is a direction perpendicular to the surface of the light-emitting layer. The light-emitting layer includes: a plurality of stacked active layers and at least one tunneling layer, and two adjacent active layers are connected by the tunneling layer. In addition, the surface emitting laser in the embodiment of the present application may also include: a first electrode and a second electrode, and the light-emitting layer is located between the first electrode and the second electrode. By applying a driving voltage to the first electrode and the second electrode, carriers can be driven to be injected into the light-emitting layer, and composite light can be emitted in the active layer in the light-emitting layer. The high-order grating is used to couple the light emitted from each active layer in the light-emitting layer, so that the light emitted from the light-emitting layer resonates along the second direction and emits along the first direction. Wherein, the second direction is a direction parallel to the surface of the light-emitting layer. In one possible implementation, a high-order grating may be provided in the surface emitting laser in the embodiment of the present application, and the high-order grating may be arranged on any side of the light-emitting layer along the first direction. In another possible implementation, a plurality of high-order gratings may also be provided in the surface emitting laser in the embodiment of the present application, and each high-order grating may be arranged on the same side of the light-emitting layer along the first direction, or each high-order grating may be distributed on both sides of the light-emitting layer along the first direction. In specific implementation, the number and position of the high-order gratings may be set according to actual needs.

[0008] In the surface emitting laser provided by the embodiment of the present application, the first reflection waveguide and the second reflection waveguide are arranged oppositely, and the light emitting layer is located between the first reflection waveguide and the second reflection waveguide, so that the light emitted by the light emitting layer can be reflected back and forth between the first reflection waveguide and the second reflection waveguide, thereby confining the light field within the light emitting layer. In addition, the high-order grating is located on at least one side of the light emitting layer along the first direction, and the high-order grating can be coupled with each active layer in the light emitting layer, so that the light emitted by the light emitting layer resonates along the second direction, thereby forming a horizontal resonant cavity between the first reflection waveguide and the second reflection waveguide. Moreover, by coupling the light emitted by the light emitting layer with the high-order grating, the light can be emitted along the first direction, thereby realizing horizontal cavity resonance and surface emission of light. By coupling the high-order grating with the multi-junction active layer, the light emitted by the light emitting layer can be pre-shaped, thereby improving the beam quality of the surface emitting laser, reducing the temperature drift coefficient, and narrowing the line width. Therefore, the surface emitting laser provided by the embodiment of the present application has a low temperature drift coefficient, a high slope efficiency, a high beam quality, and a high light output power.

[0009] In the embodiment of the present application, the high-order grating may be a grating of the second order or higher, and the high-order grating may satisfy the following formula:

[0010]

[0011] Where n represents the equivalent refractive index of the surface emitting laser, d represents the grating period of the high-order grating, λ represents the wavelength of light, and Q is a constant.

[0012] In the embodiment of the present application, the thickness of the high-order grating can be in the range of 10nm to 4000nm, for example, the thickness of the high-order grating can be in the range of 50nm to 2000nm, and the grating period of the high-order grating can be in the range of 100nm to 1000nm, for example, the grating period can be in the range of 150nm to 800nm.

[0013] In a possible implementation, the high-order grating may be a second-order buried structure. When the wavelength of the surface emitting laser is 905 nm, the grating period of the high-order grating may be about 272.4 nm, and the depth of the high-order grating may be about 120 nm. When the wavelength of the surface emitting laser is 1550 nm, the grating period of the high-order grating may be about 463.8 nm, and the depth of the high-order grating may be about 200 nm.

[0014] In another possible implementation, the high-order grating may be a second-order surface-etched grating. When the wavelength of the surface-emitting laser is 905 nm, the grating period of the high-order grating may be about 272.8 nm, and the depth of the high-order grating may be about 1460 nm. When the wavelength of the surface-emitting laser is 1550 nm, the grating period of the high-order grating may be about 464.3 nm, and the depth of the high-order grating may be about 1800 nm.

[0015] In an embodiment of the present application, the high-order grating may be a linear or curved grating, may be a linear grating with a one-dimensional uniform period, may be a nonlinear grating or a non-uniform grating, or, the high-order grating may be a two-dimensional periodic grating. For example, the high-order grating may be a two-dimensional photonic crystal structure, etc.

[0016] Furthermore, in an embodiment of the present application, at least one of the first reflection waveguide and the second reflection waveguide can be a Bragg reflection waveguide, and the structural parameters of the Bragg reflection waveguide can be adjusted to achieve precise control of the light field, effectively improve the coupling efficiency between the high-order grating and the multi-junction active layer, thereby improving the surface emission light power.

[0017] In some embodiments of the present application, the first reflection waveguide and the second reflection waveguide may both be Bragg reflection waveguides. In this way, by adjusting the structural parameters of the first reflection waveguide and the second reflection waveguide, under the cooperation of the two Bragg reflection waveguides, the light field can be more accurately regulated, and the coupling efficiency between the high-order grating and the multi-junction active layer can be further improved, thereby further improving the light extraction efficiency of the surface emission. In some other embodiments of the present application, one of the first reflection waveguide and the second reflection waveguide can be set as a Bragg reflection waveguide, and the other can be set as a total reflection waveguide. In this way, the first reflection waveguide and the second reflection waveguide are arranged relative to each other, which can also play a role in limiting the light, so that the light emitted from the light-emitting layer is reflected back and forth between the first reflection waveguide and the second reflection waveguide. By adjusting the structural parameters of the Bragg reflection waveguide, the light field can also be accurately regulated, and the coupling efficiency between the high-order grating and the multi-junction active layer can be improved, thereby further improving the light extraction efficiency of the surface emission.

[0018] Of course, in some cases, the first reflection waveguide and the second reflection waveguide may both be total reflection waveguides, which can be configured according to actual needs.

[0019] In some embodiments of the present application, the high-order grating may be a buried structure, and the high-order grating may be disposed inside a reflective waveguide. The following description will be given by taking the high-order grating disposed inside a first reflective waveguide as an example.

[0020] In some cases, the first reflection waveguide is a Bragg reflection waveguide, the second reflection waveguide may be a Bragg reflection waveguide or a total reflection waveguide, and the high-order grating may be arranged inside the first reflection waveguide. Specifically, the first reflection waveguide may include: a plurality of first dielectric layers and a plurality of second dielectric layers alternately stacked. When the structure of the first reflection waveguide is specifically set, in the first reflection waveguide, the dielectric layer closest to the light-emitting layer may be the first dielectric layer or the second dielectric layer. The refractive index of the first dielectric layer is different from that of the second dielectric layer, that is, the refractive index of the first dielectric layer may be greater than that of the second dielectric layer, or the refractive index of the first dielectric layer may be less than that of the second dielectric layer. In specific implementation, the number of layers of the first dielectric layer and the second dielectric layer in the first reflection waveguide may be set according to actual needs, which is not limited here. The first reflection waveguide may play a better role in adjusting the light field by reasonably setting the structural parameters such as the refractive index, thickness, and number of layers of the first dielectric layer and the second dielectric layer. A plurality of periodically arranged grooves are provided in at least one first dielectric layer in the first reflection waveguide, and a portion of the second dielectric layer adjacent to the grooves is embedded in each groove. The first dielectric layer with multiple grooves and part of the second dielectric layer embedded in each groove constitute the above-mentioned high-order grating. That is to say, the high-order grating is composed of periodically arranged materials with high and low refractive indexes. Optionally, the material of the first dielectric layer with multiple grooves can be different from the material of other first dielectric layers in the first reflection waveguide. Exemplarily, the material of the first dielectric layer with multiple grooves can be a material without aluminum (Al), for example, it can be gallium arsenide (GaAs) or gallium indium phosphide (GaInP), and the material of other first dielectric layers in the first reflection waveguide can be aluminum gallium arsenide (AlGaAs). Alternatively, the material of the first dielectric layer with multiple grooves can also be the same as the material of other first dielectric layers in the first reflection waveguide. The materials of each second dielectric layer in the first reflection waveguide can be the same. In the embodiment of the present application, the high-order grating is arranged inside the first reflection waveguide, so that the distance between the high-order grating and each active layer in the light-emitting layer is closer, so that the coupling effect between the high-order grating and the multi-junction active layer is better. In addition, the high-order grating is arranged inside the first reflection waveguide, and the thickness of the high-order grating is small, which can make the loss of the surface emitting laser lower.

[0021] Furthermore, the refractive index of the first dielectric layer can be greater than the refractive index of the second dielectric layer, and the high-order grating can be arranged at the position of the first dielectric layer closest to the light-emitting layer in the first reflection waveguide. That is to say, a plurality of grooves can be arranged in the first dielectric layer closest to the light-emitting layer in the first reflection waveguide, and the first dielectric layer and the second dielectric layer filled in the grooves constitute the above-mentioned high-order grating. In this way, the high-order grating is arranged at the first passive wave peak of the light-emitting layer close to the first reflection waveguide, and the light field at this position is stronger, so a higher confinement factor and coupling coefficient can be obtained.

[0022] Of course, the high-order grating can also be set at other positions in the first reflection waveguide, for example, the high-order grating can also be set in the second dielectric layer in the first reflection waveguide, which is not limited here. In the embodiment of the present application, the high-order grating can be a linear or curved grating, and the shape of the high-order grating can be set according to actual needs.

[0023] In other cases, the first reflection waveguide may be a total reflection waveguide, and the second reflection waveguide may be a Bragg reflection waveguide or a total reflection waveguide. In this case, the high-order grating may also be disposed inside the first reflection waveguide.

[0024] The surface emitting laser in the embodiment of the present application may also include: a substrate, the substrate carrying a first reflection waveguide, a second reflection waveguide, a light-emitting layer and a high-order grating. The second reflection waveguide is located between the first reflection waveguide and the substrate. In other words, the high-order grating can be arranged inside the upper reflection waveguide. In the manufacturing process, the second reflection waveguide and each film layer in the light-emitting layer are first formed in sequence on the substrate, and then each film layer and the high-order grating in the first reflection waveguide are manufactured. In this way, the step of manufacturing the high-order grating is relatively late, and the multiple grooves in the high-order grating will not affect the manufacturing process of each film layer in the light-emitting layer, so that the manufacturing difficulty of the surface emitting laser is relatively small, and the quality of the manufactured surface emitting laser is relatively good.

[0025] Of course, in some cases, the first reflection waveguide may also be located between the second reflection waveguide and the substrate. The first reflection waveguide is a Bragg reflection waveguide or a total reflection waveguide, and the second reflection waveguide may be a Bragg reflection waveguide or a total reflection waveguide. The high-order grating may be arranged inside the first reflection waveguide, that is, the high-order grating may also be arranged inside the reflection waveguide at the bottom (i.e., close to the substrate).

[0026] Several implementation methods of the high-order grating as a buried structure are introduced above. In other embodiments of the present application, the high-order grating may also be a surface-etched grating. The high-order grating may be arranged in a reflection waveguide farther from the substrate in the first reflection waveguide and the second reflection waveguide. The following takes the high-order grating arranged in the first reflection waveguide as an example to introduce the specific implementation method of the surface-etched grating in the embodiment of the present application.

[0027] The surface emitting laser in the embodiment of the present application includes a substrate, which carries a first reflection waveguide, a second reflection waveguide, a light-emitting layer and a high-order grating. The first reflection waveguide can be a Bragg reflection waveguide or a total reflection waveguide, and the second reflection waveguide can be a Bragg reflection waveguide or a total reflection waveguide. The surface of the surface emitting laser facing away from the substrate is provided with a plurality of periodically arranged grooves. The grooves in the surface emitting laser and the medium filled in each groove constitute a high-order grating. In a specific implementation, the coupling coefficient between the high-order grating and the plurality of active layers can be controlled by adjusting the depth of each groove, thereby increasing the output power of the surface emitting laser.

[0028] In a specific implementation, the second reflection waveguide may be located between the first reflection waveguide and the substrate, and a first electrode is further provided on the first reflection waveguide. In the process of manufacturing the first electrode, the material or insulating material of the first electrode may fall into the groove, and the groove may be filled with the material or insulating material of the first electrode, or a part of the groove may be filled with the material or insulating material of the first electrode, and the other part may be filled with air. In other words, the medium filled in each groove may be air, the material of the first electrode, or the insulating material.

[0029] In the manufacturing process, the second reflection waveguide, the light-emitting layer and each film layer in the first reflection waveguide can be sequentially formed on the substrate, and then the surface emitting laser is etched to form a plurality of grooves on the surface of the surface emitting laser, and each groove in the surface emitting laser and the medium filled in each groove (such as air, the material of the first electrode or the insulating material) constitute a high-order grating. In this way, the process of manufacturing the high-order grating is relatively late, and there is no need to perform a secondary epitaxial process after the high-order grating is manufactured, so that the manufacturing process of the surface emitting laser is relatively simple, and the quality of the manufactured surface emitting laser is better.

[0030] In a possible implementation, when the first reflection waveguide is a Bragg reflection waveguide, the first reflection waveguide may include: a plurality of first dielectric layers and a plurality of second dielectric layers alternately stacked, and when the structure of the first reflection waveguide is specifically set, in the first reflection waveguide, the dielectric layer closest to the light-emitting layer may be the first dielectric layer or the second dielectric layer. The refractive index of the first dielectric layer is different from the refractive index of the second dielectric layer, that is, the refractive index of the first dielectric layer may be greater than the refractive index of the second dielectric layer, or the refractive index of the first dielectric layer may be less than the refractive index of the second dielectric layer.

[0031] Each groove can penetrate from the surface of the surface emitting laser to at least a portion of the first reflection waveguide. In this way, the distance between the high-order grating and the light-emitting layer can be made closer, thereby improving the coupling effect between the high-order grating and the multi-junction active layer. In a specific implementation, each groove can penetrate from the surface of the surface emitting laser to the first dielectric layer closest to the substrate in the first reflection waveguide. In this way, the distance between the high-order grating and each active layer in the light-emitting layer is closer, thereby improving the coupling effect between the high-order grating and the multi-junction active layer. Of course, in some cases, the groove can also penetrate to the second dielectric layer closest to the substrate in the first reflection waveguide, as long as the film layer in the light-emitting layer is not damaged. Alternatively, the groove can also penetrate to the position of the first dielectric layer or the second dielectric layer that is closer to the top, which can be set according to actual needs. In an embodiment of the present application, the high-order grating can be a linear or curved grating, and the shape of the high-order grating can be set according to actual needs.

[0032] The surface emitting laser in the embodiment of the present application may also include: a first cladding, a second cladding and a cap layer. The first cladding and the second cladding are located between the substrate and the cap layer, the first reflection waveguide is located between the first cladding and the light-emitting layer, and the second reflection waveguide is located between the second cladding and the light-emitting layer. Each groove runs through the first direction from the surface of the cap layer to the first dielectric layer closest to the substrate in the first reflection waveguide. During the manufacturing process, after the second cladding, the second reflection waveguide, the light-emitting layer, the first reflection waveguide, the first cladding and the cap layer are sequentially formed on the substrate, the first reflection waveguide, the first cladding and the cap layer are etched to form a plurality of grooves. In this way, the number of times the manufacturing equipment is replaced can be reduced and the manufacturing efficiency can be improved.

[0033] In another possible implementation, the first reflection waveguide may be a total reflection waveguide, and the second reflection waveguide may be a Bragg reflection waveguide or a total reflection waveguide. The depth of each groove in the surface emitting laser penetrating the first reflection waveguide may be set according to actual needs as long as the film layer in the light emitting layer is not damaged.

[0034] The above introduces the specific configuration of the high-order grating. The following introduces the specific configuration of the light outlet in the embodiment of the present application.

[0035] The surface emitting laser in the embodiment of the present application may include: a first electrode and a second electrode, the first reflection waveguide is located between the first electrode and the light emitting layer, and the second reflection waveguide is located between the light emitting layer and the second electrode. The first reflection waveguide may be a Bragg reflection waveguide or a total reflection waveguide, and the second reflection waveguide may be a Bragg reflection waveguide or a total reflection waveguide. During the operation of the surface emitting laser, a driving voltage may be applied to the first electrode and the second electrode to drive carriers to be injected into the light emitting layer and to recombine and emit light in the active layer in the light emitting layer. A light outlet may be provided inside the first electrode or the second electrode, and since the high-order grating may enable light to be transmitted upward or downward along the first direction, light may be emitted from the light outlet in the first electrode or the second electrode.

[0036] When both the first reflection waveguide and the second reflection waveguide are Bragg reflection waveguides, the Bragg reflection waveguide includes periodically distributed high and low refractive index dielectric layers. Specifically, the first reflection waveguide may include: a plurality of first dielectric layers and a plurality of second dielectric layers alternately stacked, the refractive index of the first dielectric layer is greater than the refractive index of the second dielectric layer, each first dielectric layer and each second dielectric layer in the first reflection waveguide constitute a plurality of periods, and each period includes a first dielectric layer and a second dielectric layer. The second reflection waveguide may include: a plurality of first dielectric layers and a plurality of second dielectric layers alternately stacked, the refractive index of the first dielectric layer is greater than the refractive index of the second dielectric layer, each first dielectric layer and each second dielectric layer in the second reflection waveguide constitute a plurality of periods, and each period includes a first dielectric layer and a second dielectric layer.

[0037] In a possible implementation, a light outlet is provided inside the first electrode, the period number of the first reflection waveguide is less than or equal to the period number of the second reflection waveguide, and the second electrode can cover the light outlet in the first direction so that light is emitted from the light outlet of the first electrode. The first reflection waveguide and the second reflection waveguide can be asymmetric structures (the period numbers of the two are different), for example, the period number of the high and low refractive index medium layers in the first reflection waveguide can be 5, and the period number of the high and low refractive index medium layers in the second reflection waveguide can be 7; or, the period number of the high and low refractive index medium layers in the first reflection waveguide can be 3, and the period number of the high and low refractive index medium layers in the second reflection waveguide can be 5. The first reflection waveguide and the second reflection waveguide can also be symmetric structures (the period number of the two is the same), for example, the period number of the high and low refractive index medium layers in the first reflection waveguide and the second reflection waveguide can both be 4. In specific implementation, the period number of the high and low dielectric layers in the first reflection waveguide and the second reflection waveguide can be set according to actual needs, and examples are not given one by one here. Since a high-order grating can diffract light upward or downward along a first direction, and the more periods in the Bragg reflection waveguide, the higher the reflectivity, therefore, setting the period number of the first reflection waveguide to be less than or equal to the period number of the second reflection waveguide can enhance the light diffraction coefficient in the first direction, allowing more light to be emitted toward the light outlet in the first electrode, thereby increasing the light output power of the surface emitting laser.

[0038] In another possible implementation, when both the first reflection waveguide and the second reflection waveguide are Bragg reflection waveguides, the light outlet may also be arranged inside the second electrode, and the number of periods of the second reflection waveguide is less than or equal to the number of periods of the first reflection waveguide. Furthermore, in the first direction, the first electrode may cover the light outlet. In this way, the reflectivity of the second reflection waveguide is less than or equal to the reflectivity of the first reflection waveguide, so that more light can be emitted to the light outlet in the second electrode, thereby increasing the light output power of the surface emitting laser.

[0039] In another possible implementation, one of the first reflection waveguide and the second reflection waveguide is a Bragg reflection waveguide, and the other is a total reflection waveguide, or when both the first reflection waveguide and the second reflection waveguide are total reflection waveguides, a light outlet may be provided in the first electrode or the second electrode according to the reflectivity of the first reflection waveguide and the second reflection waveguide. Exemplarily, when the reflectivity of the first reflection waveguide is less than or equal to the reflectivity of the second reflection waveguide, the light outlet may be provided in the first electrode. When the reflectivity of the first reflection waveguide is greater than or equal to the reflectivity of the second reflection waveguide, the light outlet may be provided in the second electrode.

[0040] The light outlet in the embodiment of the present application can be set in the first electrode or the second electrode. In a possible implementation, the light outlet can be a long strip structure, for example, the light outlet can be a rectangle or other shapes, which can be set according to actual needs. The divergence angle of the laser beam is inversely proportional to the size of the light outlet. The larger the width of the light outlet in a certain direction, the smaller the divergence angle of the laser beam in this direction. In a specific implementation, the divergence angle of the laser beam can be adjusted by adjusting the length and width of the light outlet, and the output spot of the surface emitting laser can be easily controlled. In a specific implementation, by adjusting the size of the light outlet, the surface emitting laser outputs a beam with a higher collimation in a certain direction to output a line beam laser with better beam quality. Therefore, the surface emitting laser in the embodiment of the present application is applied to the laser radar without setting a complex collimation and shaping optical path, which can reduce the volume and cost of the laser radar.

[0041] In one possible implementation, an absorption region may be provided at the edge of a surface emitting laser to reduce the light emitted from the end face of the surface emitting laser and improve the quality of the output beam of the surface emitting laser. Specifically, the edge of the electrode (first electrode or second electrode) provided with a light outlet may be provided to be retracted from the edge of the cover layer (or substrate), and the region between the edge of the electrode (first electrode or second electrode) and the edge of the cover layer (or substrate) may constitute an absorption region. During the operation of the surface emitting laser, a driving voltage is applied to the first electrode and the second electrode, and only the portion of the light emitting layer corresponding to the overlapping region of the first electrode and the second electrode can cause carrier recombination and emit light under the drive of the driving voltage, and the portion of the light emitting layer corresponding to the absorption region does not emit light. When light passes through the absorption region, it will be absorbed by the material in the absorption region, and thus, the absorption region will not emit light.

[0042] The above describes the implementation method of the high-order grating as a buried structure, and the implementation method of the high-order grating as a surface-etched grating. Both of the above methods integrate the high-order grating into the reflection waveguide. In some cases, the high-order grating can also be separately set in the surface-emitting laser. Specifically, the first reflection waveguide is a Bragg reflection waveguide or a total reflection waveguide, and the second reflection waveguide is a Bragg reflection waveguide or a total reflection waveguide. The high-order grating can be located between the first reflection waveguide and the light-emitting layer; or, the high-order grating can also be set between the second reflection waveguide and the light-emitting layer. In the specific implementation, two film layers with different refractive indices can be set, and the high-order grating is formed by the periodic arrangement of high and low refractive indices. Specifically, the high-order grating can include: a first film layer and a second film layer with different refractive indices, the first film layer and the second film layer are stacked, a plurality of periodically arranged grooves are set in the first film layer, and at least part of the second film layer is embedded in each groove.

[0043] In an embodiment of the present application, a high-order grating can be coupled with a plurality of active layers stacked in a stacked manner, so that the light emitted from the light-emitting layer resonates along the second direction and emits along the first direction, and the high-order grating can be distributed throughout the resonant cavity. In addition, by adjusting the structural parameters of the Bragg reflection waveguide, the light field can be precisely regulated, and the coupling efficiency of the high-order grating and the multi-junction active layer can be effectively improved, thereby realizing horizontal cavity resonance and surface emission of light. Under the regulation of the Bragg reflection waveguide, the light field of the surface emitting laser can be composed of periodic rapid oscillation peaks. Among them, the position of each wave crest in the light field can correspond to the position of each active layer, so that the light confinement factor of the active layer can be maximized and the gain of the surface emitting laser can be improved. The position of each trough in the light field (the light field is zero) can correspond to the tunneling junction, so that the internal loss of the light field can be reduced. The position of the secondary peak in the light field can correspond to the position of the high-order grating, which can improve the coupling efficiency of the high-order grating and the multi-junction active layer. The higher the position overlap between the high-order grating and the secondary peak, the higher the coupling efficiency of the high-order grating. Moreover, the Bragg reflection waveguide can achieve very stable single-mode operation, so that multiple active layers share a large-size fundamental transverse mode, and multiple active layers share a single vertical waveguide mode, and a single high-order grating can be used to lock the wavelengths of all active layers and provide feedback output. In specific implementation, by adjusting the thickness and composition of the high and low refractive index medium layers, the light-emitting layer (the cascaded multiple active layers and the tunneling layer part) and the cladding (the first cladding and the second cladding) in the Bragg reflection waveguide, the oscillation peak swing amplitude and period of the light field can be adjusted, the light confinement factor of the active layer and the high-order grating can be increased, and the coupling coefficient in the light output direction can be increased.

[0044] In the implementation of the present application, at least one of the first reflection waveguide and the second reflection waveguide can be a Bragg reflection waveguide, and the reflection spectrum corresponding to different reflection angles can be adjusted by adjusting the structural parameters of the Bragg reflection waveguide, for example, the refractive index and thickness of each film layer in the Bragg reflection waveguide can be adjusted to optimize the reflectivity of the horizontal resonance and vertical emission at the lasing wavelength, thereby improving the efficiency of surface emission. Assuming that the lasing wavelength is near 905nm, the reflectivity corresponding to the 905nm wavelength in the reflection spectrum of the Bragg reflection waveguide in the direction of ~89° is relatively large under the design of horizontal resonance (corresponding to a reflection angle of ~89°). At the same time, in the vertical direction (corresponding to a reflection angle of ~0°), the reflectivity corresponding to the 905nm wavelength in the reflection spectrum in the direction of 0° is also relatively large. That is, the reflection spectrum corresponding to the Bragg reflection waveguide in the reflection directions of ~89° and 0° simultaneously achieves a high reflectivity at the lasing wavelength position. Thus, while the lasing wavelength meets the conditions of total reflection of horizontal resonance, more lasers can be reflected upward or downward, thereby enhancing the light output power of the surface emission.

[0045] In order to form a diode structure in the surface emitting laser, the first reflection waveguide, the second reflection waveguide, the first cladding and the second cladding may be doped with impurities, the impurities in the first reflection waveguide and the first cladding are of the same type, the impurities in the second reflection waveguide and the second cladding are of the same type, and the impurities in the first reflection waveguide and the second reflection waveguide are of different types. In this way, during the operation of the surface emitting laser, after a driving voltage is applied to the first electrode and the second electrode, carriers provided by the first electrode and the second electrode can be transmitted toward the light emitting layer and recombine and emit light in each active layer in the light emitting layer.

[0046] Specifically, each first dielectric layer and each second dielectric layer in the first reflection waveguide are doped with P-type impurities, the first cladding is doped with P-type impurities, and the second reflection waveguide is doped with N-type impurities. When the second reflection waveguide is a Bragg reflection waveguide, the first dielectric layer and the second dielectric layer in the second reflection waveguide are doped with N-type impurities, and the second cladding is doped with N-type impurities. Alternatively, each first dielectric layer and each second dielectric layer in the first reflection waveguide are doped with N-type impurities, the first cladding is doped with N-type impurities, and the second reflection waveguide is doped with P-type impurities. When the second reflection waveguide is a Bragg reflection waveguide, the first dielectric layer and the second dielectric layer in the second reflection waveguide are doped with P-type impurities, and the second cladding is doped with P-type impurities.

[0047] In addition, the surface emitting laser in the embodiment of the present application may also include: a buffer layer located on the surface of the substrate, and the substrate and the buffer layer may also be doped with impurities, and the impurity type in the substrate and the buffer layer is the same as the doping type of the adjacent reflective waveguide. Exemplarily, the substrate may include an N-type highly doped III-V group compound, which may be any one of GaAs, InP, GaSb or GaN. The buffer layer may also include an N-type highly doped material, and the buffer layer may be made of the same material as the substrate, so that the buffer layer can effectively bury the defects of the substrate and form a high-quality epitaxial surface, which is convenient for the subsequent epitaxial growth of other film layers on the buffer layer.

[0048] In an embodiment of the present application, the tunneling layer may include: a first sub-film layer and a second sub-film layer, wherein the first sub-film layer is located between the second sub-film layer and the first reflection waveguide. The first sub-film layer is doped with impurities, and the type of impurities in the first sub-film layer is consistent with the type of impurities in the second reflection waveguide. The second sub-film layer is doped with impurities, and the type of impurities in the second sub-film layer is consistent with the type of impurities in the first reflection waveguide. Exemplarily, if the first reflection waveguide is doped with P-type impurities and the second reflection waveguide is doped with N-type impurities, then the first sub-film layer is doped with N-type impurities and the second sub-film layer is doped with P-type impurities. In this way, the tunneling layer can play the role of electrical interconnection to conduct two adjacent active layers. Since the tunneling layer is a highly doped film layer, it is easy to absorb light and generate losses. Therefore, in an embodiment of the present application, by regulating the light field so that the position of the trough in the light field corresponds to the position of the tunneling layer, the light field loss can be reduced.

[0049] In a possible implementation, the light-emitting layer may further include: a plurality of third dielectric layers and a plurality of fourth dielectric layers, wherein the refractive index of the third dielectric layer is greater than the refractive index of the fourth dielectric layer. Each active layer is located between two adjacent third dielectric layers, and each tunneling layer is located between two adjacent fourth dielectric layers. Each fourth dielectric layer is doped with impurities, and the doping concentration in the fourth dielectric layer is lower than the doping concentration in the tunneling layer. The first sub-film layer and the adjacent fourth dielectric layer have different doping types, and the second sub-film layer and the adjacent fourth dielectric layer have different doping types. Exemplarily, if the first sub-film layer is doped with N-type impurities and the second sub-film layer is doped with P-type impurities, then the fourth dielectric layer adjacent to the first sub-film layer is doped with P-type impurities, and the fourth dielectric layer adjacent to the second sub-film layer is doped with N-type impurities. In a specific implementation, the active layer and the third dielectric layer may not be doped, and the tunneling layer is composed of heavily doped first and second sub-film layers. In the direction from the tunneling layer to the active layer, the doping concentration of each film layer gradually decreases.

[0050] The first reflection waveguide may be composed of a first dielectric layer with a high refractive index and a second dielectric layer with a low refractive index that are alternately distributed, and the second reflection waveguide may be composed of a first dielectric layer with a high refractive index and a second dielectric layer with a low refractive index that are alternately distributed. The refractive index and thickness of the first dielectric layer in the first reflection waveguide and the first dielectric layer in the second reflection waveguide may be the same, or they may be different. The refractive index and thickness of the second dielectric layer in the first reflection waveguide and the second dielectric layer in the second reflection waveguide may be the same, or they may be different. In a specific implementation, the light field distribution of the surface emitting laser may be adjusted by adjusting the refractive index and thickness of the first dielectric layer and the second dielectric layer in the first reflection waveguide and the refractive index and thickness of the first dielectric layer and the second dielectric layer in the second reflection waveguide.

[0051] The refractive index of the first cladding is smaller than the refractive index of each film layer in the first reflection waveguide and the second reflection waveguide, and the refractive index of the second cladding is smaller than the refractive index of each film layer in the first reflection waveguide and the second reflection waveguide. In this way, the first cladding and the second cladding can play a role in light confinement, making it easier to concentrate light in each active layer.

[0052] In addition, the refractive index of the active layer is greater than that of the third dielectric layer, and the refractive index of the tunneling layer is greater than that of the fourth dielectric layer, so that more light can be confined in the active layer and the light can pass through the tunneling layer. Furthermore, the refractive index of the third dielectric layer is lower than the refractive index of the first dielectric layer in the first reflection waveguide (or the first dielectric layer in the second reflection waveguide), so that the light emitted from the active layer can pass through the first reflection waveguide or the second reflection waveguide and be emitted.

[0053] In a second aspect, the embodiment of the present application further provides a laser emission module, and the laser emission module in the embodiment of the present application may include: any of the above-mentioned surface emitting lasers, an optical component and a scanner. The optical component is used to shape the laser emitted by the surface emitting laser. For example, the optical component may include optical elements such as a uniform light beam expander or a lens. The scanner is used to control the shaped laser to scan in a set direction.

[0054] Since the surface emitting laser in the embodiment of the present application can directly emit a linear spot laser with a highly collimated dimension, the laser emission module in the embodiment of the present application does not need to be provided with a complex optical shaping optical path, and the number of lenses in the optical module can be simplified, for example, at least two lenses can be reduced. Thus, the size of the laser emission module can be effectively reduced, and the size and cost of the laser radar can be greatly reduced.

[0055] In the third aspect, the embodiment of the present application also provides a laser radar, and the laser radar provided by the embodiment of the present application may include: the above-mentioned laser emission module and a light detector, and the light detector is used to detect the reflected light of the light emitted by the laser emission module through the object to be measured. Since the surface emitting laser in the embodiment of the present application can output a high-power, low-temperature drift, and high-grating quality line light source in a direction perpendicular to the surface, the size of the laser emission module is small, and thus the size of the laser radar including the above-mentioned laser emission module is also small, so that the laser radar has the advantages of high power, small size, and low cost, and improves the ranging performance of the laser radar.

[0056] The laser emission module in the embodiment of the present application may also include: a driving unit, the driving unit is used to drive the surface emitting laser to emit light. The laser radar in the embodiment of the present application may also include: a receiving light module and a signal processor. The receiving light module is used to receive the reflected light of the object to be measured and transmit the received reflected light to the light detector. The signal processor is used to determine the point cloud image according to the detection signal obtained by the light detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A schematic diagram of the structure of a surface emitting laser provided in an embodiment of the present application;

[0058] Figure 2 Another schematic diagram of the structure of the surface emitting laser in the embodiment of the present application;

[0059] Figure 3 Another schematic diagram of the structure of the surface emitting laser in the embodiment of the present application;

[0060] Figure 4 Another schematic diagram of the structure of the surface emitting laser in the embodiment of the present application;

[0061] Figure 5Another schematic diagram of the structure of the surface emitting laser in the embodiment of the present application;

[0062] Figure 6 Another schematic diagram of the structure of the surface emitting laser in the embodiment of the present application;

[0063] Figure 7 Another schematic diagram of the structure of the surface emitting laser in the embodiment of the present application;

[0064] Figure 8 Another schematic diagram of the structure of the surface emitting laser in the embodiment of the present application;

[0065] Fig. 9 Another schematic diagram of the structure of the surface emitting laser in the embodiment of the present application;

[0066] Fig.10 This is a schematic diagram of a top view of the structure of a surface emitting laser in an embodiment of the present application;

[0067] Fig.11 Another schematic diagram of the structure of the surface emitting laser in the embodiment of the present application;

[0068] Fig.12 A schematic diagram of the reflection spectrum of the Bragg reflection waveguide in an embodiment of the present application;

[0069] Fig.13 for Figure 1 A partial enlarged schematic diagram of the middle light-emitting layer;

[0070] Fig.14 for Figure 1 Schematic diagram of the refractive index distribution of each film layer;

[0071] Fig.15 A schematic diagram of the refractive index distribution and fundamental mode near-field distribution of a surface emitting laser in an embodiment of the present application;

[0072] Fig.16 Another schematic diagram of the refractive index distribution and fundamental mode near-field distribution of the surface emitting laser in the embodiment of the present application;

[0073] Fig.17 Another schematic diagram of the refractive index distribution and fundamental mode near-field distribution of the surface emitting laser in the embodiment of the present application;

[0074] Fig.18 A schematic diagram of the structure of a laser radar provided in an embodiment of the present application;

[0075] Fig.19 Another schematic diagram of the structure of the laser radar provided in an embodiment of the present application.

[0076] Reference numerals:

[0077] 10-substrate; 11-first reflection waveguide; 12-second reflection waveguide; 111, 121-first dielectric layer; 112, 122-second dielectric layer; 13-light-emitting layer; 131-active layer; 132-tunneling layer; 132a-first sub-film layer; 132b-second sub-film layer; 133-third dielectric layer; 134-fourth dielectric layer; 14-high-order grating; 141-first film layer; 142-second film layer; 151-first electrode ;152-second electrode;161-first cladding;162-second cladding;17-cap layer;18-buffer layer;210-laser emission module;211-surface emitting laser;212-optical component;213-scanner;214-driving unit;220-light detector;230-receiving light module;240-signal processor;U-groove;W-light outlet;M-absorption region;F1-first direction;F2-second direction. DETAILED DESCRIPTION

[0078] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings.

[0079] It should be noted that the same reference numerals in the drawings of this application represent the same or similar structures, and thus their repeated description will be omitted. The words expressing positions and directions described in this application are all explained using the drawings as examples, but they can be changed as needed, and the changes are included in the protection scope of this application. The drawings of this application are only used to illustrate the relative position relationship and do not represent the true proportion.

[0080] In the related art, edge-emitting lasers and surface-emitting distributed feedback lasers are usually used in laser radars. However, the beam quality of edge-emitting lasers is poor, and complex shaping optical paths are required, resulting in a large size of the laser radar, greater difficulty in assembly and adjustment, and higher production costs. In addition, the temperature drift coefficient of edge-emitting lasers is large, requiring large-bandwidth filters, which will result in a low signal-to-noise ratio and poor ranging capability of the laser radar. Compared with edge-emitting lasers, surface-emitting distributed feedback lasers have the advantages of high power output, low divergence angle, and low temperature drift coefficient. However, the light-emitting layer of existing surface-emitting distributed feedback lasers has only one active layer, the device coupling coefficient is small, and the slope efficiency is low. A higher drive current or a large chip size is required to achieve high peak power output, resulting in greater difficulty in designing the drive circuit.

[0081] Based on this, in order to meet the demand of laser radar for semiconductor lasers, the embodiments of the present application provide a surface emitting laser, a laser emission module and a laser radar. The surface emitting laser in the embodiments of the present application can be applied to laser radar. Of course, the surface emitting laser in the embodiments of the present application can also be applied to various laser-related equipment such as laser detection and laser imaging. The laser radar in the embodiments of the present application can be widely used in many fields such as vehicle-mounted blind spot compensation, automatic parking, whole-house intelligence, smart parks, etc. Since the surface emitting laser provided in the embodiments of the present application has the advantages of low temperature drift coefficient, high slope efficiency and high beam quality, the transmission power of the laser radar in the embodiments of the present application can be increased, and the volume and cost of the laser radar can be reduced to meet the demand of the laser radar for semiconductor lasers.

[0082] Figure 1 A schematic diagram of the structure of a surface emitting laser provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the surface emitting laser provided in the embodiment of the present application may include: two reflection waveguides, a light emitting layer 13 and a high-order grating 14. In the embodiment of the present application, for the convenience of description, the two reflection waveguides in the surface emitting laser are respectively referred to as a first reflection waveguide 11 and a second reflection waveguide 12. In the following description, the names of the first reflection waveguide and the second reflection waveguide may also be interchangeable, that is, Figure 1 The reference numeral “11” in FIG. 1 may also represent a second reflection waveguide, and the reference numeral “12” may also represent a first reflection waveguide.

[0083] The first reflection waveguide 11, the second reflection waveguide 12 and the light emitting layer 13 are stacked, and the light emitting layer 13 is located between the first reflection waveguide 11 and the second reflection waveguide 12. The first reflection waveguide 11 may be a Bragg reflection waveguide or a total reflection waveguide, and the second reflection waveguide 12 may be a Bragg reflection waveguide or a total reflection waveguide. The high-order grating 14 is located on at least one side of the light emitting layer 13 along the first direction F1. The first direction F1 is a direction perpendicular to the surface of the light emitting layer 13. The light emitting layer 13 includes: a plurality of stacked active layers 131 and at least one tunneling layer 132, and two adjacent active layers 131 are connected by the tunneling layer 132. In addition, the surface emitting laser in the embodiment of the present application may also include: a first electrode 151 and a second electrode 152, and the light emitting layer 13 is located between the first electrode 151 and the second electrode 152. By applying a driving voltage to the first electrode 151 and the second electrode 152, carriers can be driven to be injected into the light emitting layer 13, and composite light is emitted in the active layer 131 in the light emitting layer 13. The high-order grating 14 is used to couple the light emitted from each active layer 131 in the light-emitting layer 13, so that the light emitted from the light-emitting layer 13 resonates along the second direction F2 and emits along the first direction F1. The second direction F2 is a direction parallel to the surface of the light-emitting layer 13. In one possible implementation, a high-order grating 14 may be provided in the surface emitting laser in the embodiment of the present application, and the high-order grating 14 may be arranged on any side of the light-emitting layer 13 along the first direction F1. In another possible implementation, a plurality of high-order gratings 14 may also be provided in the surface emitting laser in the embodiment of the present application, and each high-order grating 14 may be arranged on the same side of the light-emitting layer 13 along the first direction F1, or each high-order grating 14 may be distributed on both sides of the light-emitting layer 13 along the first direction F1. In a specific implementation, the number and position of the high-order gratings 14 may be set according to actual needs.

[0084] In the surface emitting laser provided by the embodiment of the present application, the first reflection waveguide 11 and the second reflection waveguide 12 are arranged opposite to each other, and the light emitting layer 13 is located between the first reflection waveguide 11 and the second reflection waveguide 12, so that the light emitted from the light emitting layer 13 can be reflected back and forth between the first reflection waveguide 11 and the second reflection waveguide 12, thereby confining the light field in the light emitting layer 13. In addition, the high-order grating 14 is located on at least one side of the light emitting layer 13 along the first direction F1, and the high-order grating 14 can be coupled with each active layer 131 in the light emitting layer 13, so that the light emitted from the light emitting layer 13 resonates along the second direction F2, such as Figure 1 As shown by the thick dashed line, a horizontal resonant cavity is formed between the first reflection waveguide 11 and the second reflection waveguide 12 (the horizontal direction may be the second direction F2 in the figure). Moreover, by coupling the light emitted from the light emitting layer 13 through the high-order grating 14, the light can be emitted along the first direction F1, as shown in FIG. Figure 1As shown by the thick arrow in the middle, horizontal cavity resonance is achieved and light is emitted from the surface. By coupling the high-order grating 14 with the multi-junction active layer 131, the light emitted from the light-emitting layer 13 can be pre-shaped, thereby improving the beam quality of the surface emitting laser, reducing the temperature drift coefficient, and narrowing the line width. Therefore, the surface emitting laser provided in the embodiment of the present application has a low temperature drift coefficient, a high slope efficiency, a high beam quality, and a high light output power.

[0085] In the embodiment of the present application, the high-order grating 14 may be a grating of the second order or higher, and the high-order grating 14 may satisfy the following formula:

[0086]

[0087] Wherein, n represents the equivalent refractive index of the surface emitting laser, d represents the grating period of the high-order grating 14, λ represents the wavelength of light, and Q is a constant.

[0088] In the embodiment of the present application, the thickness of the high-order grating can be in the range of 10nm to 4000nm, for example, the thickness of the high-order grating can be in the range of 50nm to 2000nm, and the grating period of the high-order grating can be in the range of 100nm to 1000nm, for example, the grating period can be in the range of 150nm to 800nm.

[0089] In a possible implementation, the high-order grating may be a second-order buried structure. When the wavelength of the surface emitting laser is 905 nm, the grating period of the high-order grating may be about 272.4 nm, and the depth of the high-order grating may be about 120 nm. When the wavelength of the surface emitting laser is 1550 nm, the grating period of the high-order grating may be about 463.8 nm, and the depth of the high-order grating may be about 200 nm.

[0090] In another possible implementation, the high-order grating may be a second-order surface-etched grating. When the wavelength of the surface-emitting laser is 905 nm, the grating period of the high-order grating may be about 272.8 nm, and the depth of the high-order grating may be about 1460 nm. When the wavelength of the surface-emitting laser is 1550 nm, the grating period of the high-order grating may be about 464.3 nm, and the depth of the high-order grating may be about 1800 nm.

[0091] In an embodiment of the present application, the high-order grating may be a linear or curved grating, may be a linear grating with a one-dimensional uniform period, may be a nonlinear grating or a non-uniform grating, or, the high-order grating may be a two-dimensional periodic grating. For example, the high-order grating may be a two-dimensional photonic crystal structure, etc.

[0092] Furthermore, in the embodiment of the present application, at least one of the first reflection waveguide 11 and the second reflection waveguide 12 can be a Bragg reflection waveguide, and the structural parameters of the Bragg reflection waveguide can be adjusted to achieve precise control of the light field, effectively improve the coupling efficiency between the high-order grating 14 and the multi-junction active layer 131, thereby improving the surface emission light power.

[0093] like Figure 1 As shown, in some embodiments of the present application, the first reflection waveguide 11 and the second reflection waveguide 12 can both be Bragg reflection waveguides. In this way, by adjusting the structural parameters of the first reflection waveguide 11 and the second reflection waveguide 12, under the cooperation of the two Bragg reflection waveguides, the light field can be more accurately controlled, and the coupling efficiency between the high-order grating 14 and the multi-junction active layer 131 can be further improved, thereby further improving the light extraction efficiency of the surface emission. Figure 2 FIG. 1 is another schematic diagram of the structure of the surface emitting laser in the embodiment of the present application. Figure 2 As shown, in some other embodiments of the present application, one of the first reflection waveguide 11 and the second reflection waveguide 12 can be set as a Bragg reflection waveguide, and the other can be set as a total reflection waveguide, for example Figure 2 In the embodiment, the first reflection waveguide 11 is a Bragg reflection waveguide, and the second reflection waveguide 12 is a total reflection waveguide. Thus, the first reflection waveguide 11 and the second reflection waveguide 12 are arranged relative to each other, which can also limit the light, so that the light emitted from the light-emitting layer 13 is reflected back and forth between the first reflection waveguide 11 and the second reflection waveguide 12. By adjusting the structural parameters of the reflection waveguide, the light field can also be precisely controlled to improve the coupling efficiency between the high-order grating 14 and the multi-junction active layer 131, thereby further improving the light extraction efficiency of the surface emission.

[0094] Figure 3 FIG. 1 is another schematic diagram of the structure of the surface emitting laser in the embodiment of the present application. Figure 3 As shown, in some cases, the first reflection waveguide 11 and the second reflection waveguide 12 may both be total reflection waveguides, which can be configured according to actual needs.

[0095] In some embodiments of the present application, the high-order grating 14 may be a buried structure, and the high-order grating may be disposed inside a reflective waveguide. The following description will take the high-order grating disposed inside the first reflective waveguide 11 as an example.

[0096] Reference Figure 1 and Figure 2 In some cases, the first reflection waveguide 11 is a Bragg reflection waveguide, and the second reflection waveguide 12 can be Figure 1 Alternatively, the second reflection waveguide 12 may be a Bragg reflection waveguide as shown. Figure 2In the total reflection waveguide shown, the high-order grating 14 can be arranged inside the first reflection waveguide 11. Specifically, the first reflection waveguide 11 can include: a plurality of first dielectric layers 111 and a plurality of second dielectric layers 112 alternately stacked. When the structure of the first reflection waveguide 11 is specifically set, in the first reflection waveguide 11, the dielectric layer closest to the light-emitting layer 13 can be the first dielectric layer 111 or the second dielectric layer 112. The refractive index of the first dielectric layer 111 is different from the refractive index of the second dielectric layer 112, that is, the refractive index of the first dielectric layer 111 can be greater than the refractive index of the second dielectric layer 112, or the refractive index of the first dielectric layer 111 can also be less than the refractive index of the second dielectric layer 112. In the figure, the first reflection waveguide 11 is provided with four first dielectric layers 111 and four second dielectric layers 112 as an example. In specific implementation, the number of the first dielectric layer 111 and the second dielectric layer 112 in the first reflection waveguide 11 can be set according to actual needs, and is not limited here. The first reflection waveguide 11 can play a better role in adjusting the light field by reasonably setting the refractive index, thickness, number of layers and other structural parameters of the first dielectric layer 111 and the second dielectric layer 112. A plurality of periodically arranged grooves U are provided in at least one first dielectric layer 111 in the first reflection waveguide 11, and a portion of the second dielectric layer 112 adjacent to the grooves U is embedded in each groove U. The first dielectric layer 111 having a plurality of grooves U and a portion of the second dielectric layer 112 embedded in each groove U constitute the above-mentioned high-order grating 14. In other words, the high-order grating 14 is composed of periodically arranged materials with high and low refractive indices. Optionally, the material of the first dielectric layer 111 having a plurality of grooves U can be different from the material of the other first dielectric layers 111 in the first reflection waveguide 11. For example, the material of the first dielectric layer 111 having a plurality of grooves U can be a material that does not contain aluminum (Al), for example, can be gallium arsenide (GaAs) or gallium indium phosphide (GaInP), and the material of the other first dielectric layers 111 in the first reflection waveguide 11 can be aluminum gallium arsenide (AlGaAs). Alternatively, the material of the first dielectric layer 111 having the plurality of grooves U may also be the same as the material of the other first dielectric layers 111 in the first reflection waveguide 11. The materials of the second dielectric layers 112 in the first reflection waveguide 11 may be the same. In the embodiment of the present application, the high-order grating 14 is arranged inside the first reflection waveguide 11, so that the distance between the high-order grating 14 and each active layer 131 in the light-emitting layer 13 is closer, so that the coupling effect between the high-order grating 14 and the multi-junction active layer 131 is better. In addition, the high-order grating 14 is arranged inside the first reflection waveguide 11, and the thickness of the high-order grating 14 is small, so that the loss of the surface emitting laser is lower.

[0097] Furthermore, the refractive index of the first dielectric layer 111 may be greater than the refractive index of the second dielectric layer 112, and the high-order grating 14 may be arranged at a position of the first dielectric layer 111 closest to the light-emitting layer 13 in the first reflection waveguide 11. That is, a plurality of grooves U may be arranged in the first dielectric layer 111 closest to the light-emitting layer 13 in the first reflection waveguide 11, and the first dielectric layer 111 and the second dielectric layer 112 filled in the grooves U constitute the above-mentioned high-order grating 14. In this way, the high-order grating 14 is arranged at the first passive wave peak of the light-emitting layer 13 close to the first reflection waveguide 11, and the light field at this position is stronger, so a higher confinement factor and coupling coefficient can be obtained.

[0098] Of course, the high-order grating 14 can also be set at other positions in the first reflection waveguide 11. For example, the high-order grating 14 can also be set in the second dielectric layer 112 in the first reflection waveguide 11, which is not limited here. In the embodiment of the present application, the high-order grating 14 can be a linear or curved grating, and the shape of the high-order grating 14 can be set according to actual needs.

[0099] In other cases, Figure 4 FIG. 1 is another schematic diagram of the structure of the surface emitting laser in the embodiment of the present application. Figure 3 and Figure 4 As shown, the first reflection waveguide 11 may be a total reflection waveguide, and the second reflection waveguide 12 may be Figure 3 Alternatively, the second reflection waveguide 12 may be a fully reflective waveguide as shown. Figure 4 In the Bragg reflection waveguide shown in the figure, in this case, the high-order grating can also be set inside the first reflection waveguide 11, and a dielectric layer with different refractive indices can be set inside the first reflection waveguide 11. By setting a plurality of grooves U in the dielectric layer, a part of the first reflection waveguide 11 is embedded in the plurality of grooves U. The plurality of grooves U and the part of the first reflection waveguide 11 filled in the plurality of grooves U can constitute a high-order grating 14.

[0100] Continue to refer to Figure 1 , Figure 2 , Figure 3 and Figure 4, the surface emitting laser in the embodiment of the present application may also include: a substrate 10, the substrate 10 carries a first reflection waveguide 11, a second reflection waveguide 12, a light emitting layer 13 and a high-order grating 14. The second reflection waveguide 12 is located between the first reflection waveguide 11 and the substrate 10. That is to say, the high-order grating 14 can be set inside the upper reflection waveguide. From the perspective shown in the figure, the high-order grating 14 is located above the second reflection waveguide 12 and the light emitting layer 13. In the manufacturing process, the second reflection waveguide 12 and each film layer in the light emitting layer 13 are first formed on the substrate 10 in sequence, and then each film layer in the first reflection waveguide 11 and the high-order grating 14 are manufactured. In this way, the step of manufacturing the high-order grating 14 is relatively late, and the multiple grooves U in the high-order grating 14 will not affect the manufacturing process of each film layer in the light emitting layer 13, so that the manufacturing difficulty of the surface emitting laser is relatively small, and the quality of the manufactured surface emitting laser is relatively good.

[0101] Figure 5 and Figure 6 They are respectively another structural schematic diagram of the surface emitting laser in the embodiment of the present application, such as Figure 5 and Figure 6 As shown, in some cases, the first reflection waveguide 11 may also be located between the second reflection waveguide 12 and the substrate 10. The first reflection waveguide 11 may be Figure 5 and Figure 6 The Bragg reflection waveguide shown in FIG. 1 may also be a total reflection waveguide. The second reflection waveguide 12 may be Figure 5 Alternatively, the second reflection waveguide 12 may be a Bragg reflection waveguide as shown. Figure 6 The high-order grating 14 can be arranged inside the first reflective waveguide 11, that is, the high-order grating 14 can also be arranged inside the reflective waveguide at the bottom (ie, close to the substrate 10).

[0102] Combination of the above Figures 1 to 6 Several implementations of the high-order grating 14 as a buried structure are introduced. In other embodiments of the present application, the high-order grating 14 may also be a surface-etched grating. The high-order grating may be disposed in a reflection waveguide farther from the substrate in the first reflection waveguide and the second reflection waveguide. In conjunction with the accompanying drawings, the specific implementation of the surface-etched grating in the embodiment of the present application is introduced by taking the high-order grating disposed in the first reflection waveguide as an example.

[0103] Figure 7 FIG. 1 is another schematic diagram of the structure of the surface emitting laser in the embodiment of the present application. Figure 7As shown, the surface emitting laser in the embodiment of the present application includes a substrate 10, and the substrate 10 carries a first reflection waveguide 11, a second reflection waveguide 12, a light emitting layer 13 and a high-order grating 14. The first reflection waveguide 11 can be a Bragg reflection waveguide or a total reflection waveguide, and the second reflection waveguide 12 can be a Bragg reflection waveguide or a total reflection waveguide. The surface of the surface emitting laser facing away from the substrate 10 is provided with a plurality of grooves U arranged periodically, and each groove U in the surface emitting laser and the medium filled in each groove U constitute a high-order grating 14. In a specific implementation, the coupling coefficient between the high-order grating 14 and the plurality of active layers 131 can be controlled by adjusting the depth of each groove U, thereby improving the output power of the surface emitting laser.

[0104] In a specific implementation, the second reflection waveguide 12 may be located between the first reflection waveguide 11 and the substrate 10, and a first electrode 151 is further provided on the first reflection waveguide 11. In the process of manufacturing the first electrode 151, the material or insulating material of the first electrode 151 may fall into the groove U, and the groove U may be filled with the material or insulating material of the first electrode 151, or a part of the groove U may be filled with the material or insulating material of the first electrode 151, and the other part may be filled with air. That is, the medium filled in each groove U may be air, the material of the first electrode 151 or the insulating material.

[0105] During the manufacturing process, the second reflection waveguide 12, the light emitting layer 13 and each film layer in the first reflection waveguide 11 can be sequentially formed on the substrate 10, and then the surface emitting laser is etched to form a plurality of grooves U on the surface of the surface emitting laser, and each groove U in the surface emitting laser and the medium filled in each groove U (such as air, the material of the first electrode 151 or an insulating material) constitute a high-order grating 14. In this way, the process of manufacturing the high-order grating 14 is relatively late, and there is no need to perform a secondary epitaxial process after the high-order grating 14 is manufactured, so that the manufacturing process of the surface emitting laser is relatively simple, and the quality of the manufactured surface emitting laser is better.

[0106] Continue to refer to Figure 7 In a possible implementation, when the first reflection waveguide 11 is a Bragg reflection waveguide, the first reflection waveguide 11 may include: a plurality of first dielectric layers 111 and a plurality of second dielectric layers 112 that are alternately stacked. When the structure of the first reflection waveguide 11 is specifically set, in the first reflection waveguide 11, the dielectric layer closest to the light emitting layer 13 may be the first dielectric layer 111 or the second dielectric layer 112. The refractive index of the first dielectric layer 111 is different from the refractive index of the second dielectric layer 112, that is, the refractive index of the first dielectric layer 111 may be greater than the refractive index of the second dielectric layer 112, or the refractive index of the first dielectric layer 111 may be less than the refractive index of the second dielectric layer 112.

[0107] Each groove U can penetrate from the surface of the surface emitting laser to at least a portion of the first reflection waveguide 11. In this way, the distance between the high-order grating 14 and the light-emitting layer 13 can be made closer, thereby improving the coupling effect between the high-order grating 14 and the multi-junction active layer 131. In a specific implementation, each groove U can penetrate from the surface of the surface emitting laser to the first dielectric layer 111 closest to the substrate 10 in the first reflection waveguide 11. In this way, the distance between the high-order grating 14 and each active layer 131 in the light-emitting layer 13 is closer, thereby achieving a better coupling effect between the high-order grating 14 and the multi-junction active layer 131. Of course, in some cases, the groove U can also penetrate to the second dielectric layer 112 closest to the substrate 10 in the first reflection waveguide 11, as long as the film layer in the light-emitting layer 13 is not damaged. Alternatively, the groove U can also penetrate to the position of the first dielectric layer 111 or the second dielectric layer 112 that is higher, which can be set according to actual needs. In the embodiment of the present application, the high-order grating 14 may be a linear or curved grating, and the shape of the high-order grating 14 may be set according to actual needs.

[0108] The surface emitting laser in the embodiment of the present application may further include: a first cladding layer 161, a second cladding layer 162 and a cap layer 17. The first cladding layer 161 and the second cladding layer 162 are located between the substrate 10 and the cap layer 17, the first reflection waveguide 11 is located between the first cladding layer 161 and the light emitting layer 13, and the second reflection waveguide 12 is located between the second cladding layer 162 and the light emitting layer 13. Each groove U penetrates from the surface of the cap layer 17 to the first dielectric layer 111 closest to the substrate 10 in the first reflection waveguide 11 in the first direction F1. During the manufacturing process, after the second cladding layer 162, the second reflection waveguide 12, the light emitting layer 13, the first reflection waveguide 11, the first cladding layer 161 and the cap layer 17 are sequentially formed on the substrate 10, the first reflection waveguide 11, the first cladding layer 161 and the cap layer 17 are etched to form a plurality of grooves U. In this way, the number of times the manufacturing equipment is replaced can be reduced, and the manufacturing efficiency can be improved.

[0109] Figure 8 FIG. 1 is another schematic diagram of the structure of the surface emitting laser in the embodiment of the present application. Figure 8 As shown, in another possible implementation, the first reflection waveguide 11 may also be a total reflection waveguide, and the second reflection waveguide 12 may be Figure 8 The Bragg reflection waveguide shown, or the second reflection waveguide 12 can be a total reflection waveguide. The depth of each groove U penetrating the first reflection waveguide 11 in the surface emitting laser can be set according to actual needs, as long as the film layer in the light emitting layer 13 is not damaged.

[0110] The above describes the specific configuration of the high-order grating 14 . The following describes the specific configuration of the light outlet in the embodiment of the present application in conjunction with the accompanying drawings.

[0111] like Figure 1 As shown, the surface emitting laser in the embodiment of the present application may include: a first electrode 151 and a second electrode 152, a first reflection waveguide 11 is located between the first electrode 151 and the light emitting layer 13, and a second reflection waveguide 12 is located between the light emitting layer 13 and the second electrode 152. The first reflection waveguide 11 may be a Bragg reflection waveguide or a total reflection waveguide, and the second reflection waveguide 12 may be a Bragg reflection waveguide or a total reflection waveguide. During the operation of the surface emitting laser, a driving voltage may be applied to the first electrode 151 and the second electrode 152 to drive carriers to be injected into the light emitting layer 13, and to recombine and emit light in the active layer 131 in the light emitting layer 13. A light outlet W may be provided inside the first electrode 151 or the second electrode 152, and since the high-order grating 14 may enable light to be transmitted upward or downward along the first direction F1, light may be emitted from the light outlet W in the first electrode 151 or the second electrode 152.

[0112] When both the first reflection waveguide 11 and the second reflection waveguide 12 are Bragg reflection waveguides, the Bragg reflection waveguide includes periodically distributed high and low refractive index dielectric layers. Specifically, the first reflection waveguide 11 may include: a plurality of first dielectric layers 111 and a plurality of second dielectric layers 112 alternately stacked, the refractive index of the first dielectric layer 111 is greater than the refractive index of the second dielectric layer 112, each first dielectric layer 111 and each second dielectric layer 112 in the first reflection waveguide constitute a plurality of periods, and each period includes a first dielectric layer 111 and a second dielectric layer 112. The second reflection waveguide 12 may include: a plurality of first dielectric layers 121 and a plurality of second dielectric layers 122 alternately stacked, the refractive index of the first dielectric layer 121 is greater than the refractive index of the second dielectric layer 122, each first dielectric layer 121 and each second dielectric layer 122 in the second reflection waveguide 12 constitute a plurality of periods, and each period includes a first dielectric layer 121 and a second dielectric layer 122.

[0113] In one possible implementation, continue to refer to Figure 1, a light outlet W is provided inside the first electrode 151, the period number of the first reflection waveguide 11 is less than or equal to the period number of the second reflection waveguide 12, and in the first direction F1, the second electrode 152 can cover the light outlet W so that light is emitted from the light outlet W of the first electrode 151. The first reflection waveguide 11 and the second reflection waveguide 12 can be asymmetric structures (the period numbers of the two are different), for example, the period number of the high and low refractive index medium layers in the first reflection waveguide 11 can be 5, and the period number of the high and low refractive index medium layers in the second reflection waveguide 12 can be 7; or, the period number of the high and low refractive index medium layers in the first reflection waveguide 11 can be 3, and the period number of the high and low refractive index medium layers in the second reflection waveguide 12 can be 5. The first reflection waveguide 11 and the second reflection waveguide 12 can also be symmetric structures (the period numbers of the two are the same), for example, the period number of the high and low refractive index medium layers in the first reflection waveguide 11 and the second reflection waveguide 12 can both be 4. In specific implementation, the period numbers of the high and low dielectric layers in the first reflection waveguide 11 and the second reflection waveguide 12 can be set according to actual needs, and examples are not given one by one here. Since the high-order grating 14 can diffract the light upward or downward along the first direction F1, and the more period numbers in the Bragg reflection waveguide, the higher the reflectivity, therefore, setting the period number of the first reflection waveguide 11 to be less than or equal to the period number of the second reflection waveguide 12 can enhance the light diffraction coefficient in the first direction F1, so that more light is emitted to the light outlet W in the first electrode 151, thereby improving the light output power of the surface emitting laser.

[0114] In another possible implementation, when the first reflection waveguide 11 and the second reflection waveguide 12 are both Bragg reflection waveguides, the light outlet W may also be arranged inside the second electrode 152, as shown in FIG. Fig. 9 , Fig. 9 Another structural schematic diagram of the surface emitting laser in the embodiment of the present application, a light outlet W is provided inside the second electrode 152, and the number of periods of the second reflection waveguide 12 is less than or equal to the number of periods of the first reflection waveguide 11. Moreover, in the first direction F1, the first electrode 151 can cover the light outlet W. In this way, the reflectivity of the second reflection waveguide 12 is less than or equal to the reflectivity of the first reflection waveguide 11, so that more light can be emitted to the light outlet W in the second electrode 152, thereby improving the light output power of the surface emitting laser.

[0115] In another possible implementation, one of the first reflection waveguide and the second reflection waveguide is a Bragg reflection waveguide, and the other is a total reflection waveguide, or when both the first reflection waveguide and the second reflection waveguide are total reflection waveguides, a light outlet may be provided in the first electrode or the second electrode according to the reflectivity of the first reflection waveguide and the second reflection waveguide. Exemplarily, when the reflectivity of the first reflection waveguide is less than or equal to the reflectivity of the second reflection waveguide, the light outlet may be provided in the first electrode. When the reflectivity of the first reflection waveguide is greater than or equal to the reflectivity of the second reflection waveguide, the light outlet may be provided in the second electrode.

[0116] Fig.10 This is a schematic diagram of a top view of the surface emitting laser in an embodiment of the present application. Fig.10 (1) in the figure is a schematic diagram of the setting method of the light outlet. Fig.10 (2) in the figure is a schematic diagram of the far-field radiation spot. Fig.10 As shown, according to the above description, the light outlet W in the embodiment of the present application can be set in the first electrode 151 or the second electrode 152. In a possible implementation, the light outlet W can be a long strip structure, for example Fig.10 In the figure, the light outlet W is a rectangle. Of course, the light outlet W can also be other shapes and can be set according to actual needs. The divergence angle of the laser beam is inversely proportional to the size of the light outlet W. The larger the width of the light outlet W in a certain direction, the smaller the divergence angle of the laser beam in that direction. Fig.10 In Fig.10 The horizontal divergence angle θ shown is related to the length L of the light outlet W. Fig.10 Divergence angle in the vertical direction It is related to the width D of the light outlet W. In a specific implementation, the divergence angle of the laser beam can be adjusted by adjusting the length L and width D of the light outlet W, and the output spot of the surface emitting laser can be easily controlled. In a specific implementation, by adjusting the size of the light outlet W, the surface emitting laser can output a beam with a higher collimation in a certain direction to output a line beam laser with better beam quality. Therefore, the surface emitting laser in the embodiment of the present application is applied to the laser radar without setting a complex collimation and shaping optical path, which can reduce the volume and cost of the laser radar.

[0117] In a possible implementation, an absorption region M may be provided at the edge of the surface emitting laser to reduce the light emitted from the end face of the surface emitting laser and improve the quality of the output beam of the surface emitting laser. Specifically, the edge of the electrode (the first electrode 151 or the second electrode 152) provided with the light outlet W may be provided to be retracted from the edge of the cover layer 17 (or the substrate 10), and the region between the edge of the electrode (the first electrode 151 or the second electrode 152) and the edge of the cover layer 17 (or the substrate 10) may constitute the absorption region M. During the operation of the surface emitting laser, a driving voltage is applied to the first electrode 151 and the second electrode 152, and only the portion of the light emitting layer corresponding to the overlapping region of the first electrode 151 and the second electrode 152 can make carriers recombine and emit light under the driving of the driving voltage, and the portion of the light emitting layer corresponding to the absorption region M does not emit light. When light passes through the absorption region M, it will be absorbed by the material in the absorption region M, and thus, the absorption region M will not emit light.

[0118] The above describes the implementation of the high-order grating 14 as a buried structure and the implementation of the high-order grating 14 as a surface-etched grating. Both of the above methods integrate the high-order grating 14 into the reflection waveguide. In some cases, the high-order grating 14 can also be separately provided in the surface emitting laser. Fig.11 middle, Fig.11 is another structural schematic diagram of the surface emitting laser in the embodiment of the present application, the first reflection waveguide 11 is Fig.11 The Bragg reflection waveguide shown, or the first reflection waveguide 11 may also be a total reflection waveguide, and the second reflection waveguide 12 may be a Bragg reflection waveguide or a total reflection waveguide. The high-order grating 14 may be located between the first reflection waveguide 11 and the light-emitting layer 13. In a specific implementation, two film layers with different refractive indices may be provided, and the high-order grating 14 is formed by a periodic arrangement of high and low refractive indices. Specifically, the high-order grating 14 may include: a first film layer 141 and a second film layer 142 with different refractive indices, the first film layer 141 and the second film layer 142 are stacked, a plurality of periodically arranged grooves U are provided in the first film layer 141, and at least part of the second film layer 142 is embedded in each groove U. Fig.11 In the figure, the high-order grating 14 is arranged between the first reflection waveguide 11 and the light-emitting layer 13 as an example for illustration. In a specific implementation, the high-order grating 14 can also be arranged between the second reflection waveguide 12 and the light-emitting layer 13. Fig.11 In the figure, the second reflection waveguide 12 is located between the substrate 10 and the first reflection waveguide 11 as an example for illustration. In a specific implementation, the first reflection waveguide 11 may also be located between the substrate 10 and the second reflection waveguide 12.

[0119] like Figure 1As shown, in an embodiment of the present application, the high-order grating 14 can be coupled with a plurality of stacked active layers 131, so that the light emitted from the light-emitting layer 13 resonates along the second direction F2 and emits along the first direction F1, and the high-order grating 14 can be distributed in the entire resonant cavity. In addition, by adjusting the structural parameters of the Bragg reflection waveguide, the light field can be precisely regulated, and the coupling efficiency between the high-order grating 14 and the multi-junction active layer 131 can be effectively improved, thereby achieving horizontal cavity resonance and surface emission of light. Under the regulation of the Bragg reflection waveguide, the light field of the surface emitting laser can be composed of periodic rapid oscillation peaks. Among them, the position of each wave crest in the light field can correspond to the position of each active layer 131, so that the light confinement factor of the active layer 131 can be maximized, and the gain of the surface emitting laser can be improved. The position of each trough (light field is zero) in the light field can correspond to the tunneling junction 132, so that the internal loss of the light field can be reduced. The position of the secondary peak in the light field can correspond to the position of the high-order grating 14, which can improve the coupling efficiency between the high-order grating 14 and the multi-junction active layer 131. The higher the position overlap between the high-order grating 14 and the secondary peak, the higher the coupling efficiency of the high-order grating 14. Moreover, the Bragg reflection waveguide can achieve very stable single-mode operation, so that multiple active layers 131 share a large-size fundamental transverse mode, and multiple active layers 131 share a single vertical waveguide mode, which can achieve wavelength locking and feedback output of all active layers 131 by a single high-order grating 14. In specific implementation, by adjusting the thickness and composition of the high and low refractive index medium layers, the light-emitting layer 13 (part of the cascaded multiple active layers 131 and the tunneling layer 132) and the cladding (the first cladding 161 and the second cladding 162) in the Bragg reflection waveguide, the oscillation peak swing and period of the light field can be adjusted, the light confinement factor of the active layer 131 and the high-order grating 14 can be increased, and the coupling coefficient in the light output direction can be increased.

[0120] Fig.12 Schematic diagram of the reflection spectrum of the Bragg reflection waveguide in the embodiment of the present application. Fig.12 As shown, in the implementation of the present application, at least one of the first reflection waveguide and the second reflection waveguide may be a Bragg reflection waveguide, and the reflection spectra corresponding to different reflection angles may be adjusted by adjusting the structural parameters of the Bragg reflection waveguide, for example, the refractive index and thickness of each film layer in the Bragg reflection waveguide may be adjusted, so that the reflectivity of the horizontal resonance and vertical emission at the lasing wavelength is optimized, thereby improving the efficiency of the surface emission. Fig.12In the figure, assuming that the lasing wavelength is around 905nm, when the horizontal resonance is designed (corresponding to a reflection angle of ~89°), the reflectivity corresponding to the 905nm wavelength in the reflection spectrum of the Bragg reflection waveguide in the ~89° direction is relatively large. At the same time, in the vertical direction (corresponding to a reflection angle of ~0°), the reflectivity corresponding to the 905nm wavelength in the reflection spectrum in the 0° direction is also relatively large. That is, the reflection spectrum corresponding to the reflection directions of ~89° and 0° of the Bragg reflection waveguide simultaneously achieves a high reflectivity at the lasing wavelength position. Thus, while the lasing wavelength meets the conditions of total reflection of horizontal resonance, more laser light can be reflected upward or downward, thereby enhancing the light output power of the surface emission.

[0121] Continue to refer to Figure 1 In order to form a diode structure in the surface emitting laser, the first reflection waveguide 11, the second reflection waveguide 12, the first cladding 161 and the second cladding 162 may be doped with impurities, the impurities in the first reflection waveguide 11 and the first cladding 161 are of the same type, the impurities in the second reflection waveguide 12 and the second cladding 162 are of the same type, and the impurities in the first reflection waveguide 11 and the second reflection waveguide 12 are of different types. In this way, during the operation of the surface emitting laser, after a driving voltage is applied to the first electrode 151 and the second electrode 152, the carriers provided by the first electrode 151 and the second electrode 152 can be transmitted toward the light emitting layer 13, and recombine and emit light in each active layer 131 in the light emitting layer 13.

[0122] Specifically, each first dielectric layer 121 and each second dielectric layer 122 in the first reflection waveguide 11 are doped with P-type impurities, the first cladding 161 is doped with P-type impurities, and the second reflection waveguide 12 is doped with N-type impurities. When the second reflection waveguide 12 is a Bragg reflection waveguide, the first dielectric layer 121 and the second dielectric layer 122 in the second reflection waveguide 12 are doped with N-type impurities, and the second cladding 162 is doped with N-type impurities. Alternatively, each first dielectric layer 121 and each second dielectric layer 122 in the first reflection waveguide 11 are doped with N-type impurities, the first cladding 161 is doped with N-type impurities, and the second reflection waveguide 12 is doped with P-type impurities. When the second reflection waveguide 12 is a Bragg reflection waveguide, the first dielectric layer 121 and the second dielectric layer 122 in the second reflection waveguide 12 are doped with P-type impurities, and the second cladding 162 is doped with P-type impurities.

[0123] In addition, the surface emitting laser in the embodiment of the present application may further include: a buffer layer 18 located on the surface of the substrate 10, and the substrate 10 and the buffer layer 18 may also be doped with impurities, and the impurity type in the substrate 10 and the buffer layer 18 is the same as the doping type of the adjacent reflective waveguide, for example Figure 1In the embodiment, the reflection waveguide adjacent to the substrate 10 is the second reflection waveguide 12, and the substrate 10, the buffer layer 18 and the second reflection waveguide 12 have the same doping type. Exemplarily, the substrate 10 may include an N-type highly doped III-V compound, which may be any one of GaAs, InP, GaSb or GaN. The buffer layer 18 may also include an N-type highly doped material, and the buffer layer 18 may be made of the same material as the substrate 10, so that the buffer layer 18 can effectively bury the defects of the substrate 10, forming a high-quality epitaxial surface, which is convenient for subsequent epitaxial growth of other film layers on the buffer layer 18.

[0124] Fig.13 for Figure 1 A partial enlarged schematic diagram of the light-emitting layer in the middle, combined with Figure 1 and Fig.13 As shown, in the embodiment of the present application, the tunneling layer 132 may include: a first sub-film layer 132a and a second sub-film layer 132b, and the first sub-film layer 132a is located between the second sub-film layer 132b and the first reflection waveguide 11. The first sub-film layer 132a is doped with impurities, and the impurity type in the first sub-film layer 132a is consistent with the impurity type in the second reflection waveguide 12. The second sub-film layer 132b is doped with impurities, and the impurity type in the second sub-film layer 132b is consistent with the impurity type in the first reflection waveguide 11. Exemplarily, if the first reflection waveguide 11 is doped with P-type impurities and the second reflection waveguide 12 is doped with N-type impurities, the first sub-film layer 132a is doped with N-type impurities, and the second sub-film layer 132b is doped with P-type impurities. In this way, the tunneling layer 132 can play the role of electrical interconnection to conduct the two adjacent active layers 131. Since the tunneling layer 132 is a highly doped film layer, it is easy to absorb light and generate losses. Therefore, in the embodiment of the present application, by regulating the light field so that the position of the trough in the light field corresponds to the position of the tunneling layer 132, the light field loss can be reduced.

[0125] Continue to refer to Figure 1 and Fig.13, the light emitting layer 13 may further include: a plurality of third dielectric layers 133 and a plurality of fourth dielectric layers 134, wherein the refractive index of the third dielectric layer 133 is greater than the refractive index of the fourth dielectric layer 134. Each active layer 131 is located between two adjacent third dielectric layers 133, and each tunneling layer 132 is located between two adjacent fourth dielectric layers 134. Each fourth dielectric layer 134 is doped with impurities, and the doping concentration in the fourth dielectric layer 134 is lower than the doping concentration in the tunneling layer 132. The first sub-film layer 132a and the adjacent fourth dielectric layer 134 have different doping types, and the second sub-film layer 132b and the adjacent fourth dielectric layer 134 have different doping types. Exemplarily, if the first sub-film layer 132a is doped with N-type impurities and the second sub-film layer 132b is doped with P-type impurities, the fourth dielectric layer 134 adjacent to the first sub-film layer 132a is doped with P-type impurities, and the fourth dielectric layer 134 adjacent to the second sub-film layer 132b is doped with N-type impurities. In a specific implementation, the active layer 131 and the third dielectric layer 133 may be undoped, and the tunneling layer 132 is composed of a heavily doped first sub-layer 132a and a second sub-layer 132b. In the direction from the tunneling layer 132 to the active layer 131, the doping concentration of each film layer gradually decreases.

[0126] Fig.14 for Figure 1 Schematic diagram of the refractive index distribution of each film layer, combined with Figure 1 , Fig.13 and Fig.14 , the first reflection waveguide 11 may be composed of a first dielectric layer 111 with a high refractive index and a second dielectric layer 112 with a low refractive index that are alternately distributed, and the thickness of each period may be T1. Taking the second reflection waveguide 12 as a Bragg reflection waveguide as an example, the second reflection waveguide 12 is composed of a first dielectric layer 121 with a high refractive index and a second dielectric layer 122 with a low refractive index that are alternately distributed, and the thickness of each period may be T2. The refractive index and thickness of the first dielectric layer 111 in the first reflection waveguide 11 and the first dielectric layer 121 in the second reflection waveguide 12 may be the same, or they may be different. The refractive index and thickness of the second dielectric layer 112 in the first reflection waveguide 11 and the second dielectric layer 122 in the second reflection waveguide may be the same, or they may be different. In a specific implementation, the light field distribution of the surface emitting laser may be adjusted by adjusting the refractive index and thickness of the first dielectric layer 111 and the second dielectric layer 112 in the first reflection waveguide 11, and the refractive index and thickness of the first dielectric layer 121 and the second dielectric layer 122 in the second reflection waveguide 12.

[0127] The refractive index of the first cladding 161 is smaller than the refractive index of each film layer in the first reflection waveguide 11 and the second reflection waveguide 12, and the refractive index of the second cladding 162 is smaller than the refractive index of each film layer in the first reflection waveguide 11 and the second reflection waveguide 12. In this way, the first cladding 161 and the second cladding 162 can play a role in light confinement, making it easier to concentrate light in each active layer 131.

[0128] In addition, the refractive index of the active layer 131 is greater than the refractive index of the third dielectric layer 133, and the refractive index of the tunneling layer 132 is greater than the refractive index of the fourth dielectric layer 134, so that more light can be confined in the active layer 131 and the light can pass through the tunneling layer 132. In addition, the refractive index of the third dielectric layer 133 is lower than the refractive index of the first dielectric layer 111 in the first reflection waveguide 11 (or the first dielectric layer 121 in the second reflection waveguide 12), so that the light emitted from the active layer 131 can pass through the first reflection waveguide 11 or the second reflection waveguide 12 and be emitted.

[0129] Fig.15 Schematic diagram of the refractive index distribution and fundamental mode near field distribution of the surface emitting laser in the embodiment of the present application, such as Fig.15 As shown, the first reflection waveguide 11 and the second reflection waveguide 12 each include three pairs of high and low refractive index medium layers (Al 0.35 Ga 0.65 As / Al 0.2 Ga 0.8 As), that is, the number of periods of the first reflection waveguide 11 and the second reflection waveguide 12 are both 3. The light emitting layer 13 includes three cascaded active layers 131, and each active layer 131 can adopt an InGaAs double quantum well structure. Adjacent active layers 131 can be cascaded using p+ and n+ doped GaAs tunneling layers 132. The refractive index and thickness of the high refractive index layer (i.e., the third dielectric layer 133) adjacent to the active layer 131 are lower than those of the high refractive index layer (the first dielectric layer 111 or 112) of the Bragg reflection waveguide. The refractive index of the second cladding 162 is lower than that of the first cladding 161. Thus, the surface emitting laser can be operated in a complete photonic bandgap guided mode, and the complete photonic bandgap effect is used for light confinement, which can have a large gain-loss difference, so that the near-field light field of the surface emitting laser is composed of periodic peaks and nodes, and stable single transverse mode operation is achieved. From Fig.15 It can be clearly seen that the near-field distribution of the surface emitting laser in the embodiment of the present application is composed of periodic intensity oscillation peaks, and its peak intensity decays from the center to both sides. Among them, the quantum well active layer is located at the peak position of the fundamental mode near-field distribution to obtain a high light confinement factor, and the tunneling layer is located at the trough position of the fundamental mode near-field distribution (light intensity is zero), which can effectively reduce the light absorption loss in the heavily doped area.

[0130] Optionally, the high-order grating can be a buried structure, and the high-order grating can be set at the first passive peak of the active layer close to the substrate side, so as to obtain a high confinement factor and coupling coefficient. The high-order grating can also be a surface-etched grating, and the coupling coefficient can be controlled by adjusting the etching depth to increase the output power. The high-order grating can be a linear or curved grating. The light emitting direction of the surface emitting laser can be upward along the vertical epitaxial surface or downward along the vertical substrate surface.

[0131] Fig.16 FIG. 1 is another schematic diagram of the refractive index distribution and fundamental mode near-field distribution of the surface emitting laser in the embodiment of the present application. Fig.16 As shown, the first reflection waveguide 11 includes 7 pairs of high and low refractive index medium layers (Al 0.35 Ga 0.65 As / Al 0.2 Ga 0.8 As), that is, the period number of the first reflection waveguide 11 is 7. The light emitting layer 13 includes three cascaded active layers 131, and the adjacent active layers 131 can be cascaded by using a tunneling layer 132. The second reflection waveguide 12 includes five pairs of high and low refractive index dielectric layers (Al 0.35 Ga 0.65 As / Al 0.2 Ga 0.8 As), that is, the period number of the second reflection waveguide 12 is 5. By setting the period number of the first reflection waveguide 11 to be greater than the period number of the second reflection waveguide 12, the reflectivity of the first reflection waveguide 11 can be increased, so that more light is emitted from one side of the second reflection waveguide 12, thereby improving the coupling efficiency of the surface emission.

[0132] Fig.17 FIG. 1 is another schematic diagram of the refractive index distribution and fundamental mode near-field distribution of the surface emitting laser in the embodiment of the present application. Fig.17 As shown, the first reflection waveguide 11 includes 5 pairs of high and low refractive index medium layers (Al 0.35 Ga 0.65 As / Al 0.2 Ga 0.8 As), that is, the period number of the first reflection waveguide 11 is 5. The light emitting layer 13 includes three cascaded active layers 131, and the adjacent active layers 131 can be cascaded by using a tunneling layer 132. The second reflection waveguide 12 includes three pairs of high and low refractive index dielectric layers (Al 0.35 Ga 0.65 As / Al 0.2 Ga 0.8As), that is, the period number of the second reflection waveguide 12 is 3. In addition, the refractive index and thickness of the second cladding 162 can be set to be smaller than the refractive index and thickness of the first cladding 161. By setting the period number of the first reflection waveguide 11 to be greater than the period number of the second reflection waveguide 12, the reflectivity of the first reflection waveguide 11 can be increased, so that more light is emitted from one side of the second reflection waveguide 12, thereby improving the coupling efficiency of the surface emission.

[0133] Based on the same technical concept, the embodiment of the present application also provides a laser radar, Fig.18 A schematic diagram of the structure of the laser radar provided in the embodiment of the present application is shown in FIG. Fig.18 As shown, the laser radar provided in the embodiment of the present application may include: a laser emission module 210 and a light detector 220. The laser emission module may include: any of the above-mentioned surface emitting lasers 211, an optical component 212 and a scanner 213. The optical component 212 is used to shape the laser emitted by the surface emitting laser 211. For example, the optical component 212 may include optical elements such as a uniform light expander or a lens. The scanner 213 is used to control the shaped laser to scan in a set direction. The light detector 220 is used to detect the reflected light of the light emitted by the laser emission module 210 through the object to be measured.

[0134] Since the surface emitting laser in the embodiment of the present application can directly emit a linear spot laser with a highly collimated dimension, the laser emission module in the embodiment of the present application does not need to be provided with a complex optical shaping optical path, and the number of lenses in the optical module can be simplified, for example, at least two lenses can be reduced. Thus, the size of the laser emission module can be effectively reduced, and the size and cost of the laser radar can be greatly reduced, so that the laser radar has the advantages of high power, small size, and low cost, and the ranging performance of the laser radar is improved.

[0135] Fig.19 Another schematic diagram of the structure of the laser radar provided in the embodiment of the present application is as follows: Fig.19 As shown, the laser emission module in the embodiment of the present application may further include: a driving unit 214, and the driving unit 214 is used to drive the surface emitting laser 211 to emit light.

[0136] The laser radar in the embodiment of the present application may further include: a receiving light module 230 and a signal processor 240. The receiving light module 230 is used to receive the reflected light of the object to be measured and transmit the received reflected light to the light detector 220. The signal processor 240 is used to determine the point cloud image according to the detection signal detected by the light detector 220.

[0137] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0138] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present application without departing from the spirit and scope of the embodiments of the present application. Thus, if these modifications and variations of the embodiments of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A surface emitting laser, characterized in that include: A first reflection waveguide, a second reflection waveguide, a light emitting layer, and a high-order grating; The first reflective waveguide, the second reflective waveguide and the light-emitting layer are stacked, and the light-emitting layer is located between the first reflective waveguide and the second reflective waveguide; The high-order grating is located on at least one side of the light-emitting layer along a first direction, wherein the first direction is a direction perpendicular to the surface of the light-emitting layer; The light-emitting layer comprises: a plurality of active layers stacked in layers and at least one tunneling layer, wherein two adjacent active layers are connected via the tunneling layer; The high-order grating is used to couple the light emitted from each active layer in the light-emitting layer, so that the light emitted from the light-emitting layer resonates along a second direction and emits along the first direction; wherein the second direction is a direction parallel to the surface of the light-emitting layer.

2. The surface emitting laser according to claim 1, wherein At least one of the first reflection waveguide and the second reflection waveguide is a Bragg reflection waveguide.

3. The surface emitting laser according to claim 1 or 2, characterized in that The first reflection waveguide comprises: a plurality of first dielectric layers and a plurality of second dielectric layers alternately stacked, wherein the refractive index of the first dielectric layer is different from the refractive index of the second dielectric layer; At least one of the first dielectric layers in the first reflection waveguide is provided with a plurality of periodically arranged grooves, and a portion of the second dielectric layer adjacent to the grooves is embedded in the plurality of grooves; the first dielectric layer having the plurality of grooves and a portion of the second dielectric layer embedded in the plurality of grooves constitute the high-order grating.

4. The surface emitting laser according to claim 3, characterized in that Also includes: substrate; The substrate carries the first reflective waveguide, the second reflective waveguide, the light emitting layer and the high-order grating; The second reflection waveguide is located between the first reflection waveguide and the substrate, and the second reflection waveguide is a Bragg reflection waveguide or a total reflection waveguide.

5. The surface emitting laser according to claim 1 or 2, characterized in that Also includes: substrate; The substrate carries the first reflective waveguide, the second reflective waveguide, the light emitting layer and the high-order grating; A surface of the surface emitting laser facing away from the substrate is provided with a plurality of grooves arranged periodically; The plurality of grooves in the surface emitting laser and the medium filled in the plurality of grooves constitute the high-order grating.

6. The surface emitting laser according to claim 5, characterized in that The second reflection waveguide is located between the first reflection waveguide and the substrate; The first reflection waveguide comprises: a plurality of first dielectric layers and a plurality of second dielectric layers alternately stacked, wherein the refractive index of the first dielectric layer is different from the refractive index of the second dielectric layer; Each of the grooves extends from the surface of the surface emitting laser to at least a portion of the first reflective waveguide.

7. The surface emitting laser according to claim 6, characterized in that Each of the grooves extends from the surface of the surface emitting laser to the first dielectric layer in the first reflective waveguide that is closest to the substrate; The second reflection waveguide is a Bragg reflection waveguide or a total reflection waveguide.

8. The surface emitting laser according to claim 1 or 2, characterized in that Also includes: a first electrode and a second electrode; The first reflective waveguide is located between the first electrode and the light-emitting layer, and the second reflective waveguide is located between the light-emitting layer and the second electrode; The first reflection waveguide comprises: a plurality of first dielectric layers and a plurality of second dielectric layers alternately stacked, the refractive index of the first dielectric layer being greater than the refractive index of the second dielectric layer, the plurality of first dielectric layers and the plurality of second dielectric layers in the first reflection waveguide forming a plurality of periods, each of the periods comprising one first dielectric layer and one second dielectric layer; The second reflection waveguide comprises: a plurality of first dielectric layers and a plurality of second dielectric layers alternately stacked, the refractive index of the first dielectric layer is greater than the refractive index of the second dielectric layer, the plurality of first dielectric layers and the plurality of second dielectric layers in the second reflection waveguide form a plurality of periods, each of the periods comprising one first dielectric layer and one second dielectric layer; A light outlet is provided inside the first electrode, and the period number of the first reflection waveguide is less than or equal to the period number of the second reflection waveguide; or, a light outlet is provided inside the second electrode, and the period number of the second reflection waveguide is less than or equal to the period number of the first reflection waveguide.

9. The surface emitting laser according to claim 1, wherein The high-order grating is located between the second reflective waveguide and the light-emitting layer; or, the high-order grating is located between the first reflective waveguide and the light-emitting layer.

10. The surface emitting laser according to any one of claims 1 to 9, characterized in that The thickness of the high-order grating is in the range of 10nm-4000nm, and the grating period of the high-order grating is in the range of 100nm-1000nm.

11. A laser emission module, characterized in that: include: A surface emitting laser, an optical component and a scanner as claimed in any one of claims 1 to 10; The optical component is used to shape the laser light emitted by the surface emitting laser; The scanner is used to control the shaped laser to scan in a set direction.

12. A laser radar, characterized in that: include: The laser emission module and the light detector as claimed in claim 11; The light detector is used to detect the reflected light of the light emitted by the laser emission module after passing through the object to be measured.

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