Edge emitting laser and method for preparing the same

Abstract

The present application relates to an edge-emitting laser and a method for preparing the same. The edge-emitting laser includes a laser body, a high-reflection film, and a low-reflection film. The laser body has a first cavity surface and a second cavity surface opposite to each other at both ends; the high-reflection film is arranged on the second cavity surface; the low-reflection film is arranged on the first cavity surface, the reflectivity of the low-reflection film to light is lower than that of the high-reflection film, and the reflectivity of at least two parts of the low-reflection film to light in the first direction is different, and the first direction is parallel to the lateral waveguide direction of the laser body. The above-mentioned edge-emitting laser can increase the lasing probability of the transverse mode where the energy is more concentrated in the part with a larger reflectivity of the low-reflection film, thereby realizing the lasing of a specific order of transverse modes, which is conducive to the selection of the lasing mode of the edge-emitting laser.

Description

Technical Field

[0001] The present application relates to the technical field of edge emitting lasers, and in particular to an edge emitting laser and a preparation method thereof. Background Art

[0002] Semiconductor lasers, also known as laser diodes, are lasers that use semiconductor materials as gain materials. They have the advantages of small size, high efficiency, and good reliability. They are widely used in communications, sensing, security, display, industrial processing, and other fields. Among them, edge-emitting lasers (EELs) often require the deposition of materials on the front and rear surfaces of the resonant cavity to form film layers with different functions. For example, low-reflectivity films (Anti-reflective coating, AR film) and high-reflectivity films (Highly Reflective coating, HR film) are deposited on the front and rear surfaces of the cavity, respectively. These two film layers are plated on the front and rear surfaces to form a light-emitting surface (corresponding to the AR film) and a reflective surface (corresponding to the HR film).

[0003] In traditional edge-emitting lasers, since the thickness of the reflective film layer is evenly distributed on the cavity surface, there is no difference in reflectivity for different-order transverse modes, making it difficult to achieve selective lasing of different-order transverse modes. Summary of the invention

[0004] Based on this, it is necessary to provide an edge-emitting laser and a method for preparing the same in order to address the problem that traditional edge-emitting lasers are difficult to achieve selective lasing of transverse modes of different orders.

[0005] An edge emitting laser comprising:

[0006] The laser body has a first cavity surface and a second cavity surface opposite to each other at two ends;

[0007] A high reflection film is provided on the second cavity surface; and

[0008] A low-reflection film is arranged on the first cavity surface, the reflectivity of the low-reflection film to light is lower than that of the high-reflection film, and the reflectivity of at least two parts of the low-reflection film to light in a first direction is different, and the first direction is parallel to the lateral waveguide direction of the laser body.

[0009] For the above-mentioned edge-emitting laser, since the energy concentration areas of different-order transverse modes in the transverse waveguide direction are different, setting the low-reflection film in at least two parts in the first direction with different reflectivities to light can increase the lasing probability of the transverse mode where the energy is more concentrated in the part with larger reflectivity of the low-reflection film, thereby realizing the lasing of a specific-order transverse mode, which is beneficial to the selection of the lasing mode of the edge-emitting laser.

[0010] In one embodiment, the reflectivity of the middle part of the low-reflection film in the first direction to the light is different from the reflectivity of the edge part in the first direction to the light. The low-order transverse mode energy of the edge-emitting laser is usually mainly concentrated in the middle position of the transverse waveguide direction, and the high-order transverse mode energy is usually mainly concentrated in the edge position of the transverse waveguide direction. Setting the reflectivity of the low-reflection film in the middle part to be different from the reflectivity of the edge part can selectively increase the lasing probability of the low-order transverse mode or the high-order transverse mode.

[0011] In one embodiment, at least two parts of the low-reflection film in the first direction have different sizes in the second direction, and the second direction is parallel to the vertical line between the first cavity surface and the second cavity surface, and perpendicular to the first direction. By changing the sizes of parts of the low-reflection film at different positions in the first direction in the second direction, the reflectivity of the low-reflection film at different positions in the first direction can be changed, making it easier to adjust the reflectivity of the low-reflection film at different positions, thereby reducing the difficulty and cost of manufacturing edge-emitting lasers.

[0012] In one embodiment, a size of a middle portion of the low-reflection film in the first direction in the second direction is different from a size of an edge portion in the first direction in the second direction.

[0013] In one embodiment, the low-reflection film includes a first portion located in the middle of the first direction and a second portion located at an edge of the first direction, the first portion has the same size in the second direction at all locations in the first direction, the second portion has the same size in the second direction at all locations in the first direction, and the first portion and the second portion have different sizes in the second direction. The low-reflection film is provided to form at least two portions with step-wise thickness changes, so that the reflectivity of at least two portions of the low-reflection film is different, and the difficulty and cost of preparing the low-reflection film can be further reduced.

[0014] In one embodiment, the size of the low-reflection film in the second direction gradually changes from the middle position of the first direction to the edge position. Setting the thickness of the low-reflection film at different positions to change gradually can better adapt to the change of energy distribution of different order transverse modes and improve the selective lasing effect of different order transverse modes.

[0015] In one embodiment, the reflectivity of the low-reflection film to light increases with the increase of the thickness of the low-reflection film, and the size of the middle part of the low-reflection film in the first direction in the second direction is greater than the size of the edge part in the first direction in the second direction. Therefore, the reflectivity of the middle part of the low-reflection film is greater than the reflectivity of the edge position, which can increase the lasing probability of the low-order transverse mode and realize the low-order transverse mode lasing mode of the edge-emitting laser.

[0016] In one of the embodiments, the laser body includes a first metal layer, an active layer, and a second metal layer stacked in sequence in a third direction perpendicular to the first direction and the second direction, and the thickness of at least a portion of the first metal layer in the middle position in the first direction is smaller than the thickness of at least a portion of the edge position in the first direction.

[0017] In one embodiment, the reflectivity of the low-reflection film to light increases with the increase of the thickness of the low-reflection film, and the size of the middle part of the low-reflection film in the first direction in the second direction is smaller than the size of the edge part in the first direction in the second direction. Therefore, the reflectivity of the middle part of the low-reflection film is smaller than the reflectivity of the edge position, which can increase the lasing probability of the high-order transverse mode and realize the high-order transverse mode lasing mode of the edge-emitting laser.

[0018] In one of the embodiments, the laser body includes a first metal layer, an active layer, and a second metal layer stacked in sequence in a third direction perpendicular to the first direction and the second direction, and the thickness of at least a portion of the first metal layer at an edge position in the first direction is smaller than the thickness of at least a portion of the first metal layer at a middle position in the first direction, or, the first metal layer is provided with a notch at an edge position in the first direction.

[0019] A method for preparing an edge-emitting laser, comprising:

[0020] A laser bar is provided, wherein the laser bar has a first cavity surface and a second cavity surface arranged opposite to each other in a first direction, and the laser bar includes a first metal layer, an active layer, and a second metal layer stacked in sequence in a third direction, wherein the thickness of at least a portion of a portion of the first metal layer corresponding to a single laser body in a middle position in the first direction is different from the thickness of at least a portion of a portion of an edge position in the second direction, and the first direction, the second direction, and the third direction are perpendicular to each other;

[0021] The laser bar is heated, and a low-reflection film is deposited on the first cavity surface, and the reflectivity of the low-reflection film to light changes with the thickness of the low-reflection film. By changing the thickness of the first metal layer at different positions, the thermal conductivity of the first metal layer at different positions is changed, thereby changing the temperature change of the edge-emitting laser at different positions during the deposition of the low-reflection film, and then changing the deposition thickness of the low-reflection film at different positions, thereby achieving the effect of different partial thicknesses and different reflectivities at different positions of the low-reflection film, without the need to set up other additional processes, and adapting to the original preparation process of the edge-emitting laser, which is conducive to reducing the preparation difficulty and preparation cost of the edge-emitting laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of an edge-emitting laser when the thickness of the low-reflection film changes gradually in some embodiments.

[0023] Figure 2 Graph showing energy distribution of the 0th-order transverse mode and the 10th-order transverse mode of an edge-emitting laser in the transverse waveguide direction in some embodiments.

[0024] Figure 3 Schematic diagram of the structure of an edge-emitting laser when the thickness of the low-reflection film changes stepwise in some embodiments.

[0025] Figure 4 for Figure 3 A cross-sectional schematic diagram of an edge-emitting laser is shown.

[0026] Figure 5 Schematic diagram of the structure of the laser bar during the process of heating and depositing a low-reflection film in some embodiments.

[0027] Figure 6 Schematic diagram of the structure of the edge-emitting laser when the thickness of the low-reflection film changes stepwise in other embodiments.

[0028] Figure 7 for Figure 6 A cross-sectional schematic diagram of an edge-emitting laser is shown.

[0029] Reference numerals:

[0030] 10. Edge-emitting laser; 11. Laser body; 111. First cavity surface; 112. Second cavity surface; 113. First metal layer; 1131. Notch; 114. Insulation layer; 115. First contact layer; 116. First cladding layer; 117. First waveguide layer; 118. Active layer; 119. Second waveguide layer; 121. Second cladding layer; 122. Buffer layer; 123. Substrate; 124. Second metal layer; 13. High-reflection film; 14. Low-reflection film; 141. First part; 142. Second part; 15. First direction; 16. Second direction; 17. Third direction; 20. Laser bar. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0032] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0033] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0034] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0035] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0036] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0037] See also Figure 1 , Figure 1 The schematic diagram of the structure of the edge emitting laser 10 in some embodiments is shown. The edge emitting laser 10 provided in the present application can emit laser, and the edge emitting laser 10 includes but is not limited to any applicable field of communication, sensing, security, display, and industrial processing, and the type of laser emitted by the edge emitting laser 10 can be designed according to the requirements of the application field.

[0038] The edge emitting laser 10 comprises a laser body 11, a high reflection film 13 and a low reflection film 14. The two ends of the laser body 11 have a first cavity surface 111 and a second cavity surface 112 opposite to each other. The reflectivity of the low reflection film 14 to light is lower than that of the high reflection film 13. The high reflection film 13 is arranged on the second cavity surface 112, and the low reflection film 14 is arranged on the first cavity surface 111. The laser generated in the laser body 11 can oscillate in the resonant cavity formed by the first cavity surface 111 and the second cavity surface 112 and be amplified by the gain medium. When the laser is emitted to the second cavity surface 112, it will be reflected by the high reflection film 13. When the laser energy is amplified to be enough to pass through the low reflection film 14, the laser can pass through the low reflection film 14 to form the output laser of the edge emitting laser 10. Among them, the first cavity surface 111 can be regarded as the low reflection surface and the output surface of the edge emitting laser 10, and the second cavity surface 112 can be regarded as the high reflection surface of the edge emitting laser 10.

[0039] In the present application, the material and reflectivity of the low-reflection film 14 and the high-reflection film 13 to light are not limited, and can be specifically designed according to the laser energy requirements of the application scenario of the edge-emitting laser 10 and the type of the edge-emitting laser 10, which is not limited in the present application. For example, the reflectivity of the low-reflection film 14 to light at various locations can be between 5% and 15%, and the reflectivity of the high-reflection film 13 to light at various locations can be above 90%. The low-reflection film 14 and the high-reflection film 13 can be multi-layer dielectric films, for example, the low-reflection film 14 and the high-reflection film 13 can be formed by alternating deposition of film layers such as silicon dioxide (SiO2), tantalum pentoxide (Ta2O5), and titanium dioxide (TiO2).

[0040] Furthermore, in some embodiments, at least two parts of the low-reflection film 14 in the first direction 15 have different reflectivity to light, and the first direction 15 is parallel to the lateral waveguide direction of the laser body 11, which can be understood as the width direction of the laser body 11, and the lateral waveguide direction is perpendicular to the vertical line between the first cavity surface 111 and the second cavity surface 112. Figure 2 As shown, in Figure 2 The figure shows the energy distribution curves of two order transverse modes of the edge emitting laser 10 in the transverse waveguide direction, where the origin of the horizontal axis represents the middle position of the laser body 11 in the transverse waveguide direction, the values ​​in the positive and negative directions represent the distance from the middle position in the transverse waveguide direction, and the vertical axis represents the transverse mode field amplitude, where the green curve represents the field distribution of the 0th order transverse mode, and the blue curve represents the field distribution of the 10th order transverse mode. Figure 2 It can be seen that the energy concentration area of ​​the lower-order transverse mode of the edge-emitting laser 10 is closer to the middle position of the transverse waveguide direction, and the energy concentration area of ​​the higher-order transverse mode is closer to the edge position of the transverse waveguide direction, that is, the positions of the concentration areas of transverse mode energies of different orders in the transverse waveguide direction are different. In addition, when the light is incident on the low-reflection film 14, the higher the reflectivity of the low-reflection film 14 to the light, the higher the probability of laser lasing at the corresponding position, and the higher the proportion of laser lasing at the corresponding position of the edge-emitting laser 10.

[0041] Thus, by setting the reflectivity of at least two parts of the low-reflection film 14 in the first direction 15 to be different, when it is necessary to increase the proportion of a certain order or several orders of light in the laser emitted by the edge-emitting laser 10 to selectively realize a specific lasing mode, the part of the low-reflection film 14 with better reflectivity can be set in the first direction 15 at the energy concentration position of the order transverse mode corresponding to the order of lasing probability to be increased, so that the reflectivity of the low-reflection film 14 to the corresponding order transverse mode is greater than the reflectivity of other order transverse modes. For example, when it is necessary to increase the proportion of low-order transverse mode energy in the laser emitted by the edge-emitting laser 10 to realize a low-order (such as 0th order) transverse mode lasing mode, the reflectivity of the middle part of the low-reflection film 14 in the first direction 15 to the light can be set to be greater than the reflectivity of the edge part in the first direction 15 to the light, so as to increase the lasing probability of the low-order transverse mode light in the middle part. Since the low-order transverse mode energy is mainly concentrated in the middle position of the first direction 15, such a setting can effectively increase the proportion of low-order transverse modes in the light emitted by the edge-emitting laser 10. Similarly, when it is necessary to realize a high-order (for example, the 10th order) transverse mode lasing mode of the edge emitting laser 10, the reflectivity of the middle portion of the low-reflection film 14 in the first direction 15 to light can be set to be lower than the reflectivity of the edge portion in the first direction 15 to light, thereby increasing the lasing probability of the high-order transverse mode light located at the edge portion. Since the energy of the high-order transverse mode is mainly concentrated at the edge position of the first direction 15, such a setting can effectively increase the proportion of the high-order transverse mode in the light emitted by the edge emitting laser 10.

[0042] The above-mentioned edge emitting laser 10, since different orders of transverse modes have different energy concentration areas in the transverse waveguide direction, setting the low-reflection film 14 in the first direction 15 at least two parts with different reflectivities to light can increase the lasing probability of the transverse mode with more concentrated energy in the part with larger reflectivity of the low-reflection film 14, thereby realizing the lasing of a specific order of transverse mode, which is beneficial to the selection of the lasing mode of the edge emitting laser 10.

[0043] It should be noted that when the edge-emitting laser 10 needs to increase the lasing probability of a lower-order transverse mode (e.g., the 0th order) or a higher-order transverse mode (e.g., the 10th order), since the energy of the lower-order transverse mode and the higher-order transverse mode is usually concentrated in the middle position and the edge position in the transverse waveguide direction, the reflectivity of the middle part of the low-reflection film 14 in the first direction 15 to the light can be selectively set to be different from the reflectivity of the edge part in the first direction 15 to the light. When the edge-emitting laser 10 needs to increase the lasing probability of other-order transverse modes, such as increasing the lasing probability of other-order transverse modes such as the third-order, fifth-order, and seventh-order, the position of the part with higher reflectivity of the low-reflection film 14 in the first direction 15 can be adjusted according to the energy concentration position of different-order transverse modes.

[0044] Furthermore, in some embodiments, the reflectivity of the low-reflection film 14 to light varies with the size of the low-reflection film 14 in the second direction 16 (i.e., the thickness of the low-reflection film 14). For example, the reflectivity of the low-reflection film 14 to light increases with the increase of the size of the low-reflection film 14 in the second direction 16, or the reflectivity of the low-reflection film 14 to light decreases with the increase of the size of the low-reflection film 14 in the second direction 16, wherein the second direction 16 is parallel to a vertical line between the first cavity surface 111 and the second cavity surface 112, and is perpendicular to the first direction 15, and the second direction 16 is parallel to the cavity length direction of the edge-emitting laser 10. Therefore, by setting the sizes of at least two parts of the low-reflection film 14 in the first direction 15 to be different in the second direction 16, the reflectivity of at least two parts of the low-reflection film 14 in the first direction 15 to light is different. By changing the thickness of the low-reflection film 14 to adjust the reflectivity of different positions of the low-reflection film 14, the reflectivity of the low-reflection film 14 can be adjusted more conveniently, thereby reducing the difficulty and cost of preparing the edge-emitting laser 10.

[0045] Taking the edge-emitting laser 10 realizing a low-order transverse mode (e.g., the 0th order) lasing mode or a high-order transverse mode (e.g., the 10th order) lasing mode as an example, the size of the middle portion of the low-reflection film 14 in the first direction 15 in the second direction 16 can be set to be different from the size of the edge portion in the first direction 15 in the second direction 16. It can be understood that when the edge-emitting laser 10 needs to realize other orders of transverse mode lasing modes, the position of the portion of the edge-emitting laser 10 with different thicknesses in the first direction 15 can be adjusted to correspond to the energy concentration position of the corresponding order of transverse mode.

[0046] Further, taking the example that the size of the middle part of the low-reflection film 14 in the first direction 15 in the second direction 16 is different from the size of the edge part in the first direction 15 in the second direction 16, refer to Figure 3As shown, in some embodiments, the low-reflection film 14 includes a first portion 141 located in the middle of the first direction 15 and a second portion 142 located at an edge of the first direction 15. The low-reflection film 14 may be provided with two second portions 142, which are respectively located at two edge positions in the first direction 15 and respectively located on opposite sides of the first portion 141. The first portion 141 has the same size in the second direction 16 at all locations in the first direction 15, and the second portion 142 has the same size in the second direction 16 at all locations in the first direction 15, and the first portion 141 and the second portion 142 have different sizes in the second direction 16. In other words, the first portion 141 and the second portion 142 are two portions with constant thickness, and the first portion 141 and the second portion 142 have different thicknesses, and the low-reflection film 14 forms two portions with step-wise thickness changes. Two parts with step-wise thickness changes are arranged on the low-reflection film 14 so that the two parts with different thicknesses have different reflectivities to light. The low-reflection film 14 with step-wise thickness changes is easier to deposit and prepare, which is beneficial to reducing the difficulty and cost of preparing the low-reflection film 14.

[0047] Please see again Figure 1 As shown, in some embodiments, the dimensions of the low-reflection film 14 in the second direction 16 at various locations in the direction from the middle position of the first direction 15 to the edge position gradually change, that is, the thickness dimension of the low-reflection film 14 changes gradually. Since the energy of a specific order transverse mode is not concentrated in only one position, the energy of the order transverse mode usually tends to decrease from the energy concentration position to both sides, for example, the energy of the low-order transverse mode decreases from the middle position to the edge position in the transverse waveguide direction. By setting a low-reflection film 14 with a gradually changing thickness to change the reflectivity of different parts of the low-reflection film 14 to light, it is possible to better adapt to the changes in the energy distribution of different order transverse modes, improve the selective lasing effect of different order transverse modes, and improve the light extraction efficiency of the edge-emitting laser 10.

[0048] exist Figure 3 In the illustrated embodiment, taking the edge-emitting laser 10 realizing a low-order transverse mode (e.g., 0th order) lasing mode as an example, when the reflectivity of the low-reflection film 14 to light increases with the increase in the thickness of the low-reflection film 14, the size of the middle portion of the low-reflection film 14 in the first direction 15 in the second direction 16 is greater than the size of the edge portion in the first direction 15 in the second direction 16, that is, the thickness of the first portion 141 is greater than the thickness of the second portion 142. Therefore, the reflectivity of the middle portion of the low-reflection film 14 is greater than the reflectivity of the edge position, which can improve the lasing probability of the low-order transverse mode and realize the abutting transverse mode lasing mode.

[0049] Furthermore, combined with Figure 3 , Figure 4 and Figure 5As shown, in some embodiments, the laser body 11 includes a first metal layer 113 (P-side metal layer), an insulating layer 114, a first contact layer 115 (P-side contact layer), a first cladding layer 116 (P-side cladding layer), a first waveguide layer 117 (P-side waveguide layer), an active layer 118, a second waveguide layer 119 (N-side waveguide layer), a second cladding layer 121 (N-side cladding layer), a buffer layer 122, a substrate 123 and a second metal layer 124 (N-side metal layer) sequentially stacked in a third direction 17 perpendicular to the first direction 15 and the second direction 16. It can be understood that during the operation of the edge emitting laser 10, current can be injected into the current injection region through the first metal layer 113. Figure 4 The thick black arrows shown indicate the current injection direction. Under the current injection, holes and electrons in the edge-emitting laser 10 are recombined near the active layer 118 and undergo transitions to generate photons.

[0050] In some embodiments, the thickness of at least a portion of the first metal layer 113 at the middle position in the first direction 15 is less than the thickness of at least a portion of the edge position in the first direction 15. Therefore, in the process of heating the edge emitting laser 10 and depositing the low-reflection film 14, the heat conduction speed is slower at the position where the thickness of the first metal layer 113 is thinner, resulting in a lower temperature of the edge emitting laser 10 at this position, so that the thickness of the portion of the low-reflection film 14 deposited at this position is larger, forming a structure in which the thickness of the middle portion of the low-reflection film 14 is greater than that of the edge portion.

[0051] refer to Figure 5 As shown, in some embodiments, the deposition process of the low-reflection film 14 can be performed on the laser bar 20. After the low-reflection film 14 is deposited, the laser bar 20 is separated by cleavage to form multiple edge-emitting lasers 10, which is beneficial to improving the production efficiency of the edge-emitting laser 10. At the same time, the deposition area of ​​the laser bar 20 during the deposition process is large, which can reduce the difficulty and cost of the deposition process. Figure 5 It can be seen that in the process of heating the laser bar 20 and depositing the low-reflection film 14, multiple laser bars 20 can be stacked in sequence, and heat is conducted from the first metal layer 113 of the laser bar 20 on one side in the third direction 17 to other layer structures (at the same time, it is conducted from the rear end to the front end in a direction parallel to the second direction 16 and from the second cavity surface 112 to the first cavity surface 111). When the thickness of a part of the first metal layer 113 is less than the thickness of other parts, if the part is located between two laser bars 20, the two laser bars 20 will form a hollow area in the part with a smaller thickness of the first metal layer 113, resulting in the obstruction of heat conduction in the hollow area ( Figure 5 The heat conduction path indicated by the hollow arrows in FIG. 1 is shown), and the heat conducted from the rear end to the front end is also blocked at the portion with a smaller thickness of the first metal layer 113 ( Figure 5The heat conduction path indicated by the dotted arrow in the figure) makes the temperature of the laser bar 20 in this part lower than that in other parts, so that the low-reflection film 14 is deposited with a larger thickness in this part, and the low-reflection film 14 with a thickness change in a step-like manner can be formed.

[0052] Combination Figure 6 and Figure 7 As shown, in other embodiments, taking the example that the reflectivity of the low-reflection film 14 to light increases with the increase of the thickness of the low-reflection film 14, the size of the middle part of the low-reflection film 14 in the first direction 15 in the second direction 16 is smaller than the size of the edge part in the first direction 15 in the second direction 16. Therefore, the reflectivity of the middle part of the low-reflection film 14 is smaller than the reflectivity of the edge part, which can improve the lasing probability of the high-order transverse mode and realize the high-order transverse mode lasing mode of the edge emitting laser 10.

[0053] In some embodiments, the thickness of at least a portion of the first metal layer 113 at an edge position in the first direction 15 is smaller than the thickness of at least a portion of the first metal layer 113 at a middle position in the first direction 15, or a notch 1131 is provided at an edge position of the first metal layer 113 in the first direction 15. Figure 7 In the embodiment shown, taking the edge position of the first metal layer 113 in the first direction 15 as an example, the thickness of the first metal layer 113 at the position of the notch 1131 can be regarded as 0, that is, the thickness of the first metal layer 113 at the position of the notch 1131 is less than the thickness at the middle position. Figure 5 Similarly to the embodiment shown, when the thickness of at least a portion of the first metal layer 113 at the edge position is less than the thickness of at least a portion of the middle position in the first direction 15, in the process of heating the laser bar 20 and depositing the low-reflection film 14, the conduction of heat at the edge position where the thickness of the first metal layer 113 is smaller is hindered, resulting in a larger deposition thickness of the low-reflection film 14 at this position, and a low-reflection film 14 with a thickness that varies roughly in a step-like manner can be formed.

[0054] Of course, in other embodiments, depending on the material of the low-reflection film 14, the reflectivity of the low-reflection film 14 may also decrease as the thickness increases. In this case, the thickness of the low-reflection film 14 at the position corresponding to the required excitation order transverse mode may be smaller. Similarly, the thickness of at least part of the first metal layer 113 at this position may be greater than the thickness of other parts, so that the deposition thickness of the low-reflection film 14 at this position is smaller. The specific design can be based on the material and reflectivity requirements of the low-reflection film 14, which will not be repeated here.

[0055] Please see again Figure 3 , Figure 4 and Figure 5The present application also provides a method for preparing an edge emitting laser 10, which is used to prepare the edge emitting laser 10 as described in any of the above embodiments, and the preparation method comprises the following steps:

[0056] A laser bar 20 is provided, wherein the laser bar 20 has a first cavity surface 111 and a second cavity surface 112 which are arranged opposite to each other in a first direction 15, and a first metal layer 113 of the laser bar 20 corresponding to a single laser body 11 has a thickness of at least a portion of a middle position in the first direction 15 different from a thickness of at least a portion of an edge position in the second direction 16;

[0057] The laser bar 20 is heated, and a low-reflection film 14 is deposited on the first cavity surface 111 . The reflectivity of the low-reflection film 14 to light varies with the thickness of the low-reflection film 14 .

[0058] It can be understood that after the laser bar 20 is deposited to form the low-reflection film 14, the laser bar 20 can be cleaved to separate the laser bar 20 to form a plurality of edge-emitting lasers 10, wherein the first cavity surface 111 of the laser bar 20 after separation corresponds to the first cavity surface 111 of the plurality of edge-emitting lasers 10 at different parts, the first metal layer 113 of the laser bar 20 after separation corresponds to the first metal layer 113 of the plurality of edge-emitting lasers 10 at different parts, and the low-reflection film 14 after separation corresponds to the low-reflection film 14 of the plurality of edge-emitting lasers 10 at different parts, and the first metal layer 113 of each edge-emitting laser 10 has at least two parts with different thicknesses in the first direction 15, so that the low-reflection film 14 of each edge-emitting laser 10 has at least two parts with different thicknesses in the first direction 15. The specific thickness variation of the first metal layer 113 can be designed with reference to the thickness variation of the low-reflection film 14 and the lasing mode of the edge-emitting laser 10, which can be obtained by referring to the above description and will not be repeated here.

[0059] It can be seen that by changing the thickness of the first metal layer 113 at different positions, the thermal conductivity of the first metal layer 113 at different positions is changed, thereby changing the temperature change of the edge emitting laser 10 at different positions during the deposition of the low-reflection film 14, and then changing the deposition thickness of the low-reflection film 14 at different positions, thereby achieving the effect of different thicknesses and different reflectivities of different positions of the low-reflection film 14, without the need to set up other additional processes, which is compatible with the original preparation process of the edge emitting laser 10, and is conducive to reducing the preparation difficulty and preparation cost of the edge emitting laser 10. Among them, the thickness change of the first metal layer 113 can be formed by adopting a two-step deposition method when depositing the first metal layer 113, or by any other applicable process.

[0060] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. An edge emitting laser, characterized in that: include: The laser body has a first cavity surface and a second cavity surface opposite to each other at two ends; A high reflection film is provided on the second cavity surface; and A low-reflection film is disposed on the first cavity surface, wherein the reflectivity of the low-reflection film to light is lower than that of the high-reflection film, and at least two parts of the low-reflection film in a first direction have different reflectivities to light, and the first direction is parallel to the lateral waveguide direction of the laser body; The reflectivity of the low-reflection film to light increases as the thickness of the low-reflection film increases, or the reflectivity of the low-reflection film to light decreases as the thickness of the low-reflection film increases; The low-reflection film is formed on the first cavity surface by a heating deposition process, the laser body comprises a first metal layer, an active layer and a second metal layer stacked in sequence in a third direction, the thickness of at least a portion of the first metal layer in the middle position in the first direction is different from the thickness of at least a portion of the edge position in the first direction, so that the middle part and the edge part of the low-reflection film formed by deposition in the first direction have different sizes in the second direction, the second direction is parallel to a vertical line between the first cavity surface and the second cavity surface, and is perpendicular to the first direction, and the third direction is perpendicular to the first direction and the second direction.

2. The edge emitting laser according to claim 1, characterized in that The reflectivity of the middle portion of the low-reflection film in the first direction to light is different from the reflectivity of the edge portion in the first direction to light.

3. The edge emitting laser according to claim 1, characterized in that The low-reflection film includes a first portion located in the middle of the first direction and a second portion located at an edge of the first direction, the first portion has the same size in the second direction at all locations in the first direction, the second portion has the same size in the second direction at all locations in the first direction, and the first portion and the second portion have different sizes in the second direction.

4. The edge emitting laser according to claim 1, characterized in that The size of each location of the low-reflection film in the direction from the middle position to the edge position in the first direction gradually changes in the second direction.

5. The edge emitting laser according to claim 1, characterized in that The reflectivity of the low-reflection film to light increases with the increase of the thickness of the low-reflection film, and the size of the middle part of the low-reflection film in the first direction in the second direction is larger than the size of the edge part in the first direction in the second direction.

6. The edge emitting laser according to claim 5, characterized in that The thickness of at least a portion of the first metal layer at a middle position in the first direction is smaller than the thickness of at least a portion of the first metal layer at an edge position in the first direction.

7. The edge emitting laser according to claim 1, characterized in that The reflectivity of the low-reflection film to light increases with the increase of the thickness of the low-reflection film, and the size of the middle part of the low-reflection film in the first direction in the second direction is smaller than the size of the edge part in the first direction in the second direction.

8. The edge emitting laser according to claim 7, characterized in that The thickness of at least a portion of the first metal layer at an edge position in the first direction is smaller than the thickness of at least a portion of the first metal layer at a middle position in the first direction, or a notch is provided at an edge position of the first metal layer in the first direction.

9. A method for preparing an edge-emitting laser, characterized in that: Used to prepare the edge emitting laser according to any one of claims 1 to 8, the preparation method comprising: A laser bar is provided, wherein the laser bar has a first cavity facet and a second cavity facet which are arranged opposite to each other in a first direction, and the laser bar comprises a first metal layer, an active layer, and a second metal layer which are sequentially stacked in a third direction, and the thickness of at least a portion of a portion of the first metal layer corresponding to a single laser body in a middle position in the first direction is different from the thickness of at least a portion of a portion of an edge position in the first direction; The laser bar is heated and a low-reflection film is deposited on the first cavity surface, wherein the middle portion and the edge portion of the deposited low-reflection film in the first direction have different sizes in the second direction, the first direction, the second direction and the third direction are perpendicular to each other, and the reflectivity of the low-reflection film to light increases with the increase of the thickness of the low-reflection film, or decreases with the increase of the thickness of the low-reflection film.

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