Edge-emitting semiconductor laser and preparation method thereof

Abstract

The invention relates to the technical field of lasers, in particular to an edge-emitting semiconductor laser and a preparation method thereof.The edge-emitting semiconductor laser comprises an N-type electrode layer, a substrate layer, an N-type cover layer, an N-type waveguide layer, an active layer, a P-type waveguide layer and a P-type cover layer which are stacked in sequence; the N wide-ridge waveguides are located on the top surface, away from the P-type waveguide layer, of the P-type cover layer, extend in the first direction and are arranged on the top surface of the P-type cover layer at intervals in the second direction; the N narrow ridge waveguides are located on the top face, away from the P-type waveguide layer, of the P-type cover layer, the N narrow ridge waveguides and the N wide ridge waveguides are in one-to-one correspondence, the narrow ridge waveguides are located on any side, in the second direction, of the corresponding wide ridge waveguides, and the narrow ridge waveguides and the adjacent wide ridge waveguides are arranged at intervals; and the P-type electrode layer is positioned on the top surface, far away from the P-type cover layer, of the wide ridge waveguide. The invention is at least beneficial to enabling the edge-emitting semiconductor laser to output high-power and high-quality light beams.

Description

Technical Field

[0001] The present invention belongs to the technical field of lasers, and particularly relates to an edge-emitting semiconductor laser and a preparation method thereof. Background Art

[0002] Semiconductor lasers play an irreplaceable and important role in fields such as communication, radar, laser processing, or medical treatment.

[0003] Early research on semiconductor lasers mainly focused on improving the output power level. With the expansion of their application scope, for fields such as lidar, optical pumping, or fiber coupling, in addition to high power, the laser light source is also required to have good beam quality. Currently, traditional high-power semiconductor lasers adopt a wide light-emitting region structure, and the ridge width is generally greater than 100 microns. Due to multi-transverse mode lasing, the beam quality of the device is extremely poor. Traditional high-beam-quality semiconductor lasers adopt a narrow light-emitting region structure, and the ridge width is generally less than 5 microns, achieving single-transverse mode lasing, reducing the beam waist radius and divergence angle. However, due to the narrowing of the light-emitting region, the power decreases.

[0004] Currently, the methods for improving the beam quality of high-power semiconductor lasers mainly include: waveguide structure optimization, introducing loss to higher-order transverse modes using a stepped waveguide, electrode regulation (regulating the carrier distribution to introduce loss to higher-order modes), or a tapered structure, etc. However, through the scheme of optimizing the waveguide structure and electrode structure, only some higher-order modes can be filtered, and the improvement of the beam quality of the laser is limited. The tapered structure causes a serious power drop due to the reduction of the light-emitting area. These limitations make it difficult for the existing technology to meet the requirements of high-power and high-beam-quality semiconductor lasers. Summary of the Invention

[0005] In view of this, the present invention aims to provide an edge-emitting semiconductor laser and a preparation method thereof, which are at least beneficial for enabling the edge-emitting semiconductor laser to output high-power and high-quality light beams.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows:

[0007] On the one hand, the present invention provides an edge-emitting semiconductor laser, comprising: an N-type electrode layer, a substrate layer, an N-type cover layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, and a P-type cover layer, which are stacked in sequence; N wide ridge waveguides located on the top surface of the P-type cover layer away from the P-type waveguide layer, the plurality of wide ridge waveguides all extend along a first direction, and the plurality of wide ridge waveguides are arranged at intervals along a second direction on the top surface of the P-type cover layer; N narrow ridge waveguides located on the top surface of the P-type cover layer away from the P-type waveguide layer, the N narrow ridge waveguides correspond to the N wide ridge waveguides one by one, the narrow ridge waveguide is located on any one side of the corresponding wide ridge waveguide in the second direction, and the narrow ridge waveguide and the adjacent wide ridge waveguide are arranged at intervals; a P-type electrode layer, the P-type electrode layer is located on the top surface of the wide ridge waveguide away from the P-type cover layer; wherein, along the second direction, the width of the wide ridge waveguide is greater than the width of the narrow ridge waveguide, and the narrow ridge waveguide is used to attenuate the first-order mode of the wide ridge waveguide, and N is an integer greater than 1.

[0008] Further, all the narrow ridge waveguides are located on the same side of the corresponding wide ridge waveguides in the second direction.

[0009] Further, along the second direction, the width of the narrow ridge waveguide is in the range of 1.5 μm to 4 μm, and the width of the wide ridge waveguide is in the range of 7 μm to 9 μm.

[0010] Further, along the direction perpendicular to the top surface of the P-type cover layer, the height of the wide ridge waveguide is the same as the height of the narrow ridge waveguide, and the height of the wide ridge waveguide is in the range of 0.7 μm to 1.2 μm.

[0011] Further, along the second direction, the distance between the narrow ridge waveguide and the corresponding wide ridge waveguide is in the range of 2.2 μm to 4 μm.

[0012] Further, both the wide ridge waveguide and the narrow ridge waveguide are straight waveguides.

[0013] Further, along the second direction, the widths of two adjacent wide ridge waveguides are different.

[0014] On the other hand, the present invention provides a method for preparing an edge-emitting semiconductor laser, comprising: forming a substrate layer, an N-type cover layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, and a P-type cover layer which are stacked in sequence; forming N wide ridge waveguides and N narrow ridge waveguides on the top surface of the P-type cover layer away from the P-type waveguide layer, wherein the plurality of wide ridge waveguides all extend along a first direction, and the plurality of wide ridge waveguides are arranged at intervals along a second direction on the top surface of the P-type cover layer, the N narrow ridge waveguides correspond to the N wide ridge waveguides one by one, the narrow ridge waveguide is located on any one side of the corresponding wide ridge waveguide in the second direction, and the narrow ridge waveguide and the adjacent wide ridge waveguide are arranged at intervals, wherein, along the second direction, the width of the wide ridge waveguide is greater than the width of the narrow ridge waveguide, and the narrow ridge waveguide is used to loss the first-order mode of the wide ridge waveguide; forming a P-type electrode layer and an N-type electrode layer, the P-type electrode layer is located on the top surface of the wide ridge waveguide away from the P-type cover layer, and the N-type electrode layer is located on the surface of the substrate layer away from the N-type cover layer.

[0015] Compared with the prior art, the present invention can achieve the following beneficial effects: the edge-emitting semiconductor laser provided by the present invention realizes the output of high power in the fundamental transverse mode of the edge-emitting semiconductor laser through the design of the ridge waveguide structure. Specifically, by injecting current into the wide ridge waveguide, the gain of the fundamental transverse mode is increased, and the corresponding narrow ridge waveguide is used for mode filtering, increasing the loss of the first-order mode, improving the beam quality while realizing high-power output, and the structure of the edge-emitting semiconductor laser of the present invention is simple. Therefore, its preparation method is relatively simple, the preparation cost is low, and it is conducive to large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0017] Figure 1 is a schematic structural diagram of an edge-emitting semiconductor laser provided by an embodiment of the present invention;

[0018] Figure 2 is a schematic diagram of the fundamental transverse mode distribution state of a partial edge-emitting semiconductor laser provided by an embodiment of the present invention;

[0019] Figure 3 is a schematic diagram of the distribution state of the high-order mode of a partial edge-emitting semiconductor laser provided by an embodiment of the present invention;

[0020] Figure 4 is a top view of an edge-emitting semiconductor laser provided by an embodiment of the present invention and a schematic diagram of the corresponding fundamental transverse mode distribution state. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0022] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0023] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. are based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0024] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0025] The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0026] Reference Figure 1 and Figure 4, on the one hand, the present invention provides an edge-emitting semiconductor laser, comprising: an N-type electrode layer 101, a substrate layer 102, an N-type cover layer 103, an N-type waveguide layer 104, an active layer 105, a P-type waveguide layer 106, and a P-type cover layer 107 stacked in sequence; N wide-ridge waveguides 110 located on the top surface of the P-type cover layer 107 away from the P-type waveguide layer 106, the plurality of wide-ridge waveguides 110 all extend along the first direction X, and the plurality of wide-ridge waveguides 110 are arranged at intervals along the second direction Y on the top surface of the P-type cover layer 107; N narrow-ridge waveguides 111 located on the top surface of the P-type cover layer 107 away from the P-type waveguide layer 106, the N narrow-ridge waveguides 111 correspond to the N wide-ridge waveguides 110 one by one, the narrow-ridge waveguide 111 is located on any side of the corresponding wide-ridge waveguide 110 in the second direction Y, and the narrow-ridge waveguide 111 and the adjacent wide-ridge waveguide 110 are arranged at intervals; a P-type electrode layer 109, the P-type electrode layer 109 is located on the top surface of the wide-ridge waveguide 110 away from the P-type cover layer 107; wherein, along the second direction Y, the width of the wide-ridge waveguide 110 is greater than the width of the narrow-ridge waveguide 111, and the narrow-ridge waveguide 111 is used to loss the first-order mode of the wide-ridge waveguide 110, and N is an integer greater than 1.

[0027] Further, both the wide-ridge waveguide and the narrow-ridge waveguide are straight waveguides. The optical field distribution inside the straight waveguide is along the oscillation direction, while the optical field distribution in the curved waveguide will generate scattering loss at the curved position, and there is no such problem in the straight waveguide. Therefore, the fundamental mode light inside the narrow-ridge waveguide can always be coupled with the high-order mode light in the wide-ridge waveguide. Compared with the curved waveguide, the coupling effect of the present invention is stronger and the loss of the high-order mode is greater. And the straight waveguide of the present invention can form a stable laser oscillation for forming a semiconductor laser, and it is difficult for the curved waveguide to achieve an effective laser oscillation.

[0028] It should be noted that the edge-emitting semiconductor laser provided by the present invention is a semiconductor laser array. By introducing loss to the high-order mode light in the wide-ridge waveguide through the narrow-ridge waveguide, a fundamental mode laser with high beam quality is generated in the wide-ridge waveguide. Compared with the existing single-mode semiconductor laser array, the present invention realizes high power and high beam quality.

[0029] In some embodiments, along the second direction, the widths of two adjacent wide-ridge waveguides are the same. In other embodiments, along the second direction, the widths of two adjacent wide-ridge waveguides are different. In this way, it is beneficial to reduce the influence of mode coupling between adjacent wide-ridge waveguides and further improve the beam quality of each wide-ridge waveguide. Specifically, the mode coupling between the fundamental modes of the wide-ridge waveguides can be reduced, which is beneficial to further improve the beam quality. It should be noted that for the narrow-ridge waveguide, the width of the narrow-ridge waveguide corresponding to the wide-ridge waveguide can be further determined according to the set requirement of the propagation constant matching between the first-order mode of the wide-ridge waveguide and the fundamental mode of the narrow-ridge waveguide.

[0030] In some embodiments, 1 < N ≤ 5. The wide-ridge waveguide 110 arranged in an array can ensure that the edge-emitting semiconductor laser has a larger gain area and can provide higher gain for the fundamental transverse mode.

[0031] Reference Figure 3 , due to the presence of the narrow-ridge waveguide 111, the high-order modes in the wide-ridge waveguide 110 are lost. And since there is no current injection into the narrow-ridge waveguide 111, the high-order modes can be effectively filtered out to ensure the fundamental transverse mode output of the edge-emitting semiconductor laser.

[0032] That is to say, in the edge-emitting semiconductor laser provided by the present invention, the ridge waveguide structure includes a narrow-ridge waveguide 111 and a wide-ridge waveguide 110. There is no current injection into the narrow-ridge waveguide 111, and current injection is carried out in the wide-ridge waveguide 110. The function of the narrow-ridge waveguide 111 is to increase the loss of the first-order mode through the coupling effect between the fundamental mode in the narrow-ridge waveguide 111 and the first-order mode in the wide-ridge waveguide 110. The function of the wide-ridge waveguide 110 is to provide higher output power through a larger cross-sectional area. And since the current injection in the wide-ridge waveguide 110 can provide higher modal gain for the fundamental transverse mode, this will effectively filter out the high-order modes and ensure laser emission in the fundamental transverse mode state.

[0033] It should be noted that along the second direction Y, the width of the wide-ridge waveguide 110 is set to the maximum width that only supports the fundamental transverse mode and the first-order transverse mode. The width of the narrow-ridge waveguide 111 is set so that the propagation constants of the fundamental mode in the narrow-ridge waveguide 111 and the first-order transverse mode in the wide-ridge waveguide 110 are the same. Along the direction perpendicular to the top surface of the P-type cover layer 107, the height of the wide-ridge waveguide 110 or the narrow-ridge waveguide 111 satisfies that the two first-order transverse modes existing in the wide-ridge waveguide 110 have large losses, and the losses of the two first-order transverse modes existing in the wide-ridge waveguide 110 are the same or nearly the same. Along the second direction Y, the distance between the narrow-ridge waveguide 111 and the corresponding wide-ridge waveguide 110 is set so that the two first-order transverse modes existing in the wide-ridge waveguide 110 have large losses, and the losses of the two first-order transverse modes are the same or nearly the same. Here, nearly the same means that the difference between the two is less than 5% of the target loss, and the target loss is the larger value of the two.

[0034] In some embodiments, along the first direction X, the length of the edge-emitting semiconductor laser is in the range of 500 μm to 5000 μm. Along the second direction Y, the width of the edge-emitting semiconductor laser is in the range of 100 μm to 400 μm. The thickness of the edge-emitting semiconductor laser is in the range of 100 μm to 300 μm. Along the first direction X, the length of the wide-ridge waveguide 110 is the same as the length of the narrow-ridge waveguide 111, and the length of the wide-ridge waveguide 110 or the narrow-ridge waveguide 111 is the same as the cavity length of the edge-emitting semiconductor laser.

[0035] Furthermore, all the narrow ridge waveguides 111 are located on the same side of the corresponding wide ridge waveguides 110 in the second direction Y. In this way, with the performance of the edge-emitting semiconductor laser remaining unchanged, the size of the edge-emitting semiconductor laser is smaller in the second direction Y, which is beneficial to the miniaturization of the device.

[0036] Furthermore, in the second direction Y, the width of the narrow ridge waveguide 111 is in the range of 1.5 μm to 4 μm, and the width of the wide ridge waveguide 110 is in the range of 7 μm to 9 μm.

[0037] Furthermore, in the direction perpendicular to the top surface of the P-type capping layer 107, the heights of the wide ridge waveguide 110 and the narrow ridge waveguide 111 are the same, and the height of the wide ridge waveguide 110 is in the range of 0.7 μm to 1.2 μm.

[0038] Furthermore, in the second direction Y, the spacing between the narrow ridge waveguide 111 and the corresponding wide ridge waveguide 110 is in the range of 2.2 μm to 4 μm.

[0039] In some embodiments, in the second direction Y, the spacing between the narrow ridge waveguide 111 and the adjacent wide ridge waveguide 110 is in the range of 2.2 μm to 4 μm.

[0040] It should be noted that the spacing between the narrow ridge waveguide and the corresponding wide ridge waveguide should ensure that the propagation constants of the fundamental mode of the narrow ridge waveguide and the first-order mode of the wide ridge waveguide are the same.

[0041] In some embodiments, in the first direction X, the length of the edge-emitting semiconductor laser needs to satisfy the condition that the crosstalk value between the fundamental mode of the narrow ridge waveguide and the first-order mode of the corresponding wide ridge waveguide is equal to or close to 1, and the crosstalk value between the fundamental modes of adjacent wide ridge waveguides is equal to or close to 0, and in the first direction X, the length (cavity length) of the edge-emitting semiconductor laser is in the range of 1 mm to 4 mm.

[0042] It should be noted that the design of the material components, thickness, and doping concentration of each layer in the edge-emitting semiconductor laser provided by the present invention is the same as that of the currently widely used and mature edge-emitting semiconductor lasers. Specifically, the corresponding material system can be selected according to the emission wavelength band. For example, if the emission wavelength band of the edge-emitting semiconductor laser is in the range of 600 nm to 1200 nm, the gallium arsenide material system can be used; if the emission wavelength band of the edge-emitting semiconductor laser is in the range of 1300 nm to 1700 nm, the indium phosphide material system can be used.

[0043] Next, taking the gallium arsenide material system as an example, the specific structure of the edge-emitting semiconductor laser provided by the present invention will be described in detail.

[0044] In some embodiments, the edge-emitting semiconductor laser includes: a substrate layer 102 made of N-type GaAs; an N-type cap layer 103 made of AlGaAs, where the Al composition in the N-type cap layer 103 can be in the range of 0.2 to 0.6, the thickness of the N-type cap layer 103 can be in the range of 0.1 μm to 3 μm, the dopant of the N-type cap layer 103 can be Si, and the doping concentration of Si can be in the range of 1E17 / cm 3 ~1E19 / cm 3 ; an N-type waveguide layer 104 made of AlGaAs, where the Al composition in the N-type waveguide layer 104 can be in the range of 0.05 to 0.7, the thickness of the N-type waveguide layer 104 can be in the range of 0.1 μm to 10 μm, the dopant of the N-type waveguide layer 104 can be Si, and the doping concentration of Si can be in the range of 1E16 / cm 3 ~8E18 / cm 3 ; an active layer 105 that is not actively doped. The active layer 105 can be a barrier layer / quantum well layer / barrier layer structure. The material of the barrier layer can be AlGaAs, the material of the quantum well layer can be InGaAs, the In composition in the quantum well layer is in the range of 0 to 0.5, the Al composition in the barrier layer is in the range of 0 to 0.5, the thickness of the barrier layer can be in the range of 1 nm to 200 nm, and the thickness of the quantum well layer can be in the range of 1 nm to 20 nm. The emission wavelength band of the edge-emitting semiconductor laser can be in the range of 700 nm to 1200 nm; a P-type waveguide layer 106 made of AlGaAs, where the Al composition in the P-type waveguide layer 106 can be in the range of 0.05 to 0.7, the thickness of the P-type waveguide layer 106 can be in the range of 0.1 μm to 10 μm, the dopant of the P-type waveguide layer 106 can be C, and the doping concentration of C can be in the range of 1E16 / cm 3 ~8E18 / cm 3 ; a P-type cap layer 107 made of AlGaAs. In the P-type cap layer 107, the Al composition is in the range of 0.4 to 0.6, the thickness of the P-type cap layer 107 can be in the range of 0.1 μm to 3 μm, the dopant of the P-type cap layer 107 can be C, and the doping concentration of C can be in the range of 1E17 / cm 3 ~1E19 / cm 3 .

[0045] In some embodiments, the edge-emitting semiconductor laser further includes a P-type electrode layer 109. The P-type electrode layer 109 is located on the top surface of the wide ridge waveguide 110 away from the P-type cap layer 107. The thickness of the P-type electrode layer 109 can be between 200 nm and 500 nm, and the material of the P-type electrode layer 109 can include at least one of titanium, platinum, gold, nickel, and germanium.

[0046] In some embodiments, the thickness of the N-type electrode layer 101 is the same as that of the P-type electrode layer 109, and the material of the N-type electrode layer 101 is the same as that of the P-type electrode layer 109.

[0047] In some embodiments, the edge-emitting semiconductor laser further includes an insulating layer 108. The P-type electrode layer 109 penetrates through the insulating layer 108 and is in contact with the top surface of the wide ridge waveguide 110. The material of the insulating layer 108 may include at least one of SiO2 and Si3N4, and the thickness of the insulating layer 108 may be in the range of 50 nm to 100 nm.

[0048] On the other hand, the present invention provides a method for manufacturing an edge-emitting semiconductor laser, including: forming a substrate layer 102, an N-type cover layer 103, an N-type waveguide layer 104, an active layer 105, a P-type waveguide layer 106, and a P-type cover layer 107 that are sequentially stacked; forming N wide ridge waveguides 110 and N narrow ridge waveguides 111 on the top surface of the P-type cover layer 107 away from the P-type waveguide layer 106. The plurality of wide ridge waveguides 110 all extend along the first direction X, and the plurality of wide ridge waveguides 110 are arranged at intervals along the second direction Y on the top surface of the P-type cover layer 107. The N narrow ridge waveguides 111 correspond to the N wide ridge waveguides 110 one by one. The narrow ridge waveguide 111 is located on any one side of the corresponding wide ridge waveguide 110 in the second direction Y. The narrow ridge waveguide 111 and the adjacent wide ridge waveguide 110 are arranged at intervals. Wherein, along the second direction Y, the width of the wide ridge waveguide 110 is greater than that of the narrow ridge waveguide 111, and the narrow ridge waveguide 111 is used to attenuate the first-order mode of the wide ridge waveguide 110; forming a P-type electrode layer 109 and an N-type electrode layer 101. The P-type electrode layer 109 is located on the top surface of the wide ridge waveguide 110 away from the P-type cover layer 107, and the N-type electrode layer 101 is located on the surface of the substrate layer 102 away from the N-type cover layer 103.

[0049] Taking the gallium arsenide material system as an example, the method for manufacturing the edge-emitting semiconductor laser provided by the present invention will be described in detail below.

[0050] In some embodiments, the method for manufacturing an edge-emitting semiconductor laser includes:

[0051] Step 1: Design a first photolithography layout for etching to form a ridge waveguide structure, and design a second photolithography layout for forming the P-type electrode layer 109;

[0052] Step 2: On a substrate layer 102 made of N-type GaAs, an N-type cover layer 103, an N-type waveguide layer 104, an active layer 105, a P-type waveguide layer 106, and an initial P-type cover layer are sequentially formed by epitaxial growth;

[0053] Step 3: Perform photolithography and dry etching on the top surface of the initial P-type capping layer away from the P-type waveguide layer 106 using the first photolithography layout to fabricate a P-type capping layer 107 with a wide-ridge waveguide 110 and a narrow-ridge waveguide 111 on the top surface;

[0054] Step 4: Use a plasma-enhanced chemical vapor deposition equipment to grow an insulating layer 108 on the P-type capping layer 107, on the wide-ridge waveguide 110, and on the narrow-ridge waveguide 111;

[0055] Step 5: Perform photolithography and dry etching processes using the second photolithography layout to fabricate an injection window for the P-type electrode layer in the insulating layer 108;

[0056] Step 6: Use a metal film evaporation equipment to grow a P-type electrode layer 109 in the injection window of the P-type electrode layer;

[0057] Step 7: Thinning, polishing, and cleaning are sequentially performed on the side of the substrate layer 102 away from the N-type capping layer 103. An N-type electrode layer 101 is sputtered on the surface of the substrate layer 102 away from the N-type capping layer 103, and then an annealing process is carried out to form a good ohmic contact between the N-type electrode layer 101 and the substrate layer 102;

[0058] Step 8: Cleave the entire structure formed above into bars. After depositing an anti-reflection film on the backlight side, cleave the bars into chips to obtain an edge-emitting semiconductor laser.

[0059] The distribution of the fundamental transverse mode in the edge-emitting semiconductor laser provided by the present invention is as Figure 2 shown. It can be seen from Figure 2 that the larger gain area of the wide-ridge waveguide 110 can provide higher gain for the fundamental transverse mode; the distribution of the higher-order modes in the edge-emitting semiconductor laser provided by the present invention is as Figure 3 shown. Due to the presence of the narrow-ridge waveguide 111, the higher-order modes in the wide-ridge waveguide 110 are lost, and there is no current injection in the narrow-ridge waveguide 111, effectively filtering out the higher-order modes.

[0060] In the edge-emitting semiconductor laser provided by the present invention, there are two modes, namely the fundamental mode and the first-order mode, in the wide-ridge waveguide 110, and only one mode exists in the narrow-ridge waveguide 111. The mode in the narrow-ridge waveguide 111 is designed to have the same propagation constant as the first-order mode of the wide-ridge waveguide 110 to form a resonant mode. Thus, by injecting current into the wide-ridge waveguide 110, that is, selectively pumping the wide-ridge waveguide 110, higher modal gain can be provided for the fundamental mode, effectively filtering out the higher-order modes and enabling the laser to emit in a single-mode state.

[0061] It should be understood that the various forms of processes shown above can be used, with steps reordered, added or deleted. For example, the steps described in the disclosure of the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and no limitation is imposed herein.

[0062] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An edge-emitting semiconductor laser, characterized in that, Comprising: An N-type electrode layer, a substrate layer, an N-type cover layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, and a P-type cover layer stacked in sequence; N wide ridge waveguides located on the top surface of the P-type cover layer away from the P-type waveguide layer, the plurality of wide ridge waveguides all extend along a first direction, and the plurality of wide ridge waveguides are arranged at intervals along a second direction on the top surface of the P-type cover layer; N narrow ridge waveguides located on the top surface of the P-type cover layer away from the P-type waveguide layer, the N narrow ridge waveguides correspond to the N wide ridge waveguides one by one, the narrow ridge waveguide is located on any one side of the corresponding wide ridge waveguide in the second direction, and the narrow ridge waveguide and the adjacent wide ridge waveguide are arranged at intervals; A P-type electrode layer, the P-type electrode layer is located on the top surface of the wide ridge waveguide away from the P-type cover layer; Wherein, along the second direction, the width of the wide ridge waveguide is greater than the width of the narrow ridge waveguide, the narrow ridge waveguide is used to loss the first-order mode of the wide ridge waveguide, and N is an integer greater than 1.

2. The edge-emitting semiconductor laser according to claim 1, wherein, All the narrow ridge waveguides are located on the same side of the corresponding wide ridge waveguide in the second direction.

3. The edge-emitting semiconductor laser according to claim 1, characterized in that, Along the second direction, the width of the narrow ridge waveguide is in the range of 1.5 μm to 4 μm, and the width of the wide ridge waveguide is in the range of 7 μm to 9 μm.

4. The edge-emitting semiconductor laser according to claim 1 or 3, characterized in that, Along the direction perpendicular to the top surface of the P-type cover layer, the height of the wide ridge waveguide is the same as the height of the narrow ridge waveguide, and the height of the wide ridge waveguide is in the range of 0.7 μm to 1.2 μm.

5. The edge-emitting semiconductor laser according to claim 1, characterized in that, Along the second direction, the spacing between the narrow ridge waveguide and the corresponding wide ridge waveguide is in the range of 2.2 μm to 4 μm.

6. The edge-emitting semiconductor laser according to claim 1, wherein Both the wide ridge waveguide and the narrow ridge waveguide are straight waveguides.

7. The edge-emitting semiconductor laser according to claim 1, characterized in that, Along the second direction, the widths of two adjacent wide ridge waveguides are different.

8. A method for preparing an edge-emitting semiconductor laser, characterized in that, Comprising: Forming a substrate layer, an N-type cover layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, and a P-type cover layer stacked in sequence; Forming N wide ridge waveguides and N narrow ridge waveguides located on the top surface of the P-type cover layer away from the P-type waveguide layer, the plurality of wide ridge waveguides all extend along a first direction, and the plurality of wide ridge waveguides are arranged at intervals along a second direction on the top surface of the P-type cover layer, the N narrow ridge waveguides correspond to the N wide ridge waveguides one by one, the narrow ridge waveguide is located on any one side of the corresponding wide ridge waveguide in the second direction, and the narrow ridge waveguide and the adjacent wide ridge waveguide are arranged at intervals, wherein, along the second direction, the width of the wide ridge waveguide is greater than the width of the narrow ridge waveguide, the narrow ridge waveguide is used to loss the first-order mode of the wide ridge waveguide, and N is an integer greater than 1; Forming a P-type electrode layer and an N-type electrode layer, the P-type electrode layer is located on the top surface of the wide ridge waveguide away from the P-type cover layer, and the N-type electrode layer is located on the surface of the substrate layer away from the N-type cover layer.

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