Semiconductor laser structure capable of reducing the hole burning effect

Abstract

This invention relates to a semiconductor laser structure that reduces the hole-burning effect. The structure comprises, from bottom to top, a lower electrode layer, a substrate layer, a lower capping layer, a lower waveguide layer, a multiple quantum well layer, an upper waveguide layer, an upper capping layer, a ridge layer, a patterned contact layer, and an upper electrode layer. The patterned contact layer is composed of multiple contact strips and multiple insulating strips arranged alternately. The dimensions of the contact strips along the arrangement direction gradually increase from the middle contact strip to the contact strips at both ends of the arrangement direction. The dimensions of each insulating strip are equal along the arrangement direction. This semiconductor laser structure that reduces the hole-burning effect utilizes the patterned contact layer to form a non-uniform grid structure. Current injection is customized through the non-uniform grid between the upper and lower electrode layers, reducing heat accumulation in the central region of the semiconductor laser structure and the hole-burning effect caused by high photon density. Ultimately, this improves laser stability, further reduces leakage current, improves high-temperature characteristics, and enhances reliability.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and in particular to a semiconductor laser structure that can reduce the hole-burning effect. Background Technology

[0002] Semiconductor lasers possess advantages such as small size, long lifespan, low energy consumption, simple manufacturing, easy mass production, low cost, wide wavelength coverage, and high electro-optical conversion efficiency, leading to their widespread application in fields such as fiber optic communication, optical storage, CD laser record players, and laser printers. Quantum well high-power semiconductor lasers, on the other hand, are geared towards precision machining, printing, the medical field, and solid-state pump sources. Laser technology has become an indispensable technology in modern life, closely related to industrial processing, medical aesthetics, fiber optic communication, and the recent boom in autonomous driving and intelligent robots.

[0003] Current research on quantum well lasers mainly focuses on three types of materials: InGaAlP-GaAs, GaAlAs-GaAs, and InGaAsP-InP. The concept of strained quantum wells has been proposed, optimizing the valence band characteristics within the material and improving the performance of semiconductor light-emitting devices. High-power GaAs-based semiconductor lasers can achieve photoelectric conversion efficiencies of up to 50%, with some reaching 70%, significantly enhancing their practicality and expanding their application areas. Semiconductor lasers are experiencing rapid growth in industrial processing, showing strong momentum in recent years and are expected to capture an even larger market share in the future.

[0004] Currently, existing high-power semiconductor lasers often encounter instability problems, mainly due to instability caused by local high temperatures, such as the spatial hole burning effect, which leads to instability in mode and power output. Summary of the Invention

[0005] The purpose of this invention is to provide a semiconductor laser structure that can reduce the hole-burning effect, thereby improving its high-temperature characteristics, stability, and reliability.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A semiconductor laser structure that reduces hole burning effect is characterized by comprising, from bottom to top, a lower electrode layer, a substrate layer, a lower capping layer, a lower waveguide layer, a multiple quantum well layer, an upper waveguide layer, an upper capping layer, a ridge layer, a patterned contact layer, and an upper electrode layer, wherein the patterned contact layer is composed of multiple contact strips and multiple insulating strips arranged alternately, the size of the contact strips along the arrangement direction gradually increases from the middle contact strip to the contact strips at both ends of the arrangement direction, and the size of each insulating strip along the arrangement direction is equal.

[0008] In one embodiment of this application, along the arrangement direction of the contact strip and the insulating strip, the dimensions of the ridge layer, the patterned contact layer, and the upper electrode layer are smaller than the dimensions of the lower electrode layer, the substrate layer, the lower cover layer, the lower waveguide layer, the multiple quantum well layer, the upper waveguide layer, and the upper cover layer.

[0009] In one embodiment of this application, the contact strip is an InGaAs contact strip that has undergone P-type modulation doping, the size of the middle contact strip along the arrangement direction is 0.5 micrometers to 1 micrometer, and the size of the contact strip along the stacking direction is 0.2 micrometers to 0.4 micrometers.

[0010] In one embodiment of this application, the insulating strip is a silicon oxide insulating strip or a silicon nitride insulating strip, the size of the insulating strip along the arrangement direction is 1 micrometer to 3 micrometers, and the size of the insulating strip along the stacking direction is the same as that of the contact strip.

[0011] In one embodiment of this application, the upper electrode layer includes a titanium layer and a first gold layer stacked from bottom to top. The titanium layer has a size of 50nm to 100nm along the stacking direction, and the first gold layer has a size of not less than 300nm along the stacking direction.

[0012] In one embodiment of this application, the ridge layer is an InP ridge layer or an AlGaAs ridge layer that has undergone P-type modulation doping, and the size of the ridge layer along the stacking direction is 0.4 micrometers to 0.6 micrometers.

[0013] In one embodiment of this application, the capping layer is an InP capping layer or an AlGaAs capping layer that has undergone P-type modulation doping, and the size of the capping layer along the stacking direction is 0.8 micrometers to 1 micrometer.

[0014] In one embodiment of this application, the upper waveguide layer is an InGaAsP waveguide layer or an AlGaInAs waveguide layer. The size of the upper waveguide layer along the stacking direction is 0.2 micrometers to 0.8 micrometers. The refractive index of the upper waveguide layer gradually decreases from bottom to top, and the minimum refractive index value is not lower than 3.0.

[0015] In one embodiment of this application, the multiple quantum well layer is an InGaAsP multiple quantum well layer or an AlGaInAs multiple quantum well layer. The dimensions of the multiple quantum well layer along the stacking direction are 10 nm to 100 nm. The multiple quantum well layer includes 1 to 10 quantum wells. The thickness of the well layer is 4 nm to 10 nm, and the thickness of the barrier layer is 4 nm to 10 nm. The barrier confinement structure of the multiple quantum well layer adopts double barrier layer confinement. The electronic band step between the first barrier layer and the adjacent well layer is greater than 0.3 electron volts, and the hole band step between the second barrier layer and the adjacent well layer is greater than 0.3 electron volts. The thicknesses of the double barrier layers of the multiple quantum well layer are different.

[0016] In one embodiment of this application, the lower waveguide layer is an InGaAsP waveguide layer or an AlGaInAs waveguide layer. The size of the lower waveguide layer along the stacking direction is 0.2 micrometers to 0.8 micrometers. The refractive index of the lower waveguide layer gradually increases from bottom to top, and the minimum refractive index value is not lower than 3.6.

[0017] In one embodiment of this application, the lower capping layer is an InP lower capping layer or an AlGaAs lower capping layer that has undergone N-type modulation doping, and the size of the lower capping layer along the stacking direction is 1.0 micrometer to 1.5 micrometer.

[0018] In one embodiment of this application, the substrate layer is an N-type modulated doped GaAs substrate layer or an InP substrate layer, and the size of the substrate layer along the stacking direction is 70 micrometers to 90 micrometers.

[0019] In one embodiment of this application, the lower electrode layer is stacked from bottom to top with a second gold layer and a gold-germanium-nickel layer. The second gold layer has a dimension of not less than 1000 nm along the stacking direction, and the surface of the second gold layer is covered with pits. The period size of the pits is 5 micrometers to 10 micrometers, and the depth is 200 nm to 600 nm. The surface particle size of the second gold layer is 8000 mesh to 10000 mesh, and the dimension of the gold-germanium-nickel layer along the stacking direction is 50 nm to 100 nm.

[0020] As can be seen from the above technical solutions, the present invention discloses a semiconductor laser structure that can reduce the hole burning effect. The semiconductor laser structure that can reduce the hole burning effect includes a lower electrode layer, a substrate layer, a lower capping layer, a lower waveguide layer, a multiple quantum well layer, an upper waveguide layer, an upper capping layer, a ridge layer, a patterned contact layer, and an upper electrode layer stacked sequentially from bottom to top. The patterned contact layer is composed of multiple contact strips and multiple insulating strips arranged alternately. The size of the contact strips along the arrangement direction gradually increases from the middle contact strip to the contact strips at both ends of the arrangement direction. The size of each insulating strip along the arrangement direction is equal.

[0021] The aforementioned semiconductor laser structure that reduces the hole-burning effect utilizes a patterned contact layer to form a non-uniform grid structure. The upper and lower electrode layers are injected with current through the non-uniform grid, which reduces the heat accumulation in the central region of the semiconductor laser structure and the hole-burning effect caused by high photon density. Ultimately, this improves the laser's stability, further reduces leakage current, improves high-temperature characteristics, and enhances reliability. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a semiconductor laser structure that can reduce the hole burning effect, provided in an embodiment of the present invention.

[0024] In the picture:

[0025] 1 is the lower electrode layer; 2 is the substrate layer; 3 is the lower cover layer; 4 is the lower waveguide layer; 5 is the multiple quantum well layer; 6 is the upper waveguide layer; 7 is the upper cover layer; 8 is the ridge layer; 9 is the patterned contact layer; 901 is the contact strip; 902 is the insulating strip; 10 is the upper electrode layer. Detailed Implementation

[0026] The core of this invention is to provide a semiconductor laser structure that can reduce the hole burning effect. The structural design of this semiconductor laser structure enables it to improve high-temperature characteristics, stability, and reliability.

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Please see Figure 1 , Figure 1 This is a schematic diagram of a semiconductor laser structure that can reduce the hole burning effect, provided in an embodiment of the present invention.

[0029] This invention discloses a semiconductor laser structure that can reduce the hole burning effect. The semiconductor laser structure that can reduce the hole burning effect includes a lower electrode layer 1, a substrate layer 2, a lower capping layer 3, a lower waveguide layer 4, a multiple quantum well layer 5, an upper waveguide layer 6, an upper capping layer 7, a ridge layer 8, a patterned contact layer 9, and an upper electrode layer 10, which are stacked sequentially from bottom to top.

[0030] The patterned contact layer 9 is composed of multiple contact strips 901 and multiple insulating strips 902 arranged alternately. The size of the contact strips 901 along the arrangement direction gradually increases from the middle contact strip 901 to the contact strips 901 at both ends of the arrangement direction. The size of each insulating strip 902 along the arrangement direction is equal.

[0031] Compared with the prior art, the semiconductor laser structure provided by the embodiments of the present invention can reduce the hole burning effect by using a patterned contact layer 9 to form a non-uniform grid structure. The upper and lower electrode layers 1 are injected with current through the non-uniform grid, which reduces the heat accumulation in the central area of ​​the semiconductor laser structure and the hole burning effect caused by high photon density. Ultimately, the laser stability is improved, leakage current is further reduced, high temperature characteristics are improved, and reliability is increased.

[0032] Along the arrangement direction of contact strip 901 and insulating strip 902, the ridge layer 8, patterned contact layer 9, and upper electrode layer 10 have the same size and are smaller than the size of lower electrode layer 1, substrate layer 2, lower cover layer 3, lower waveguide layer 4, multi-quantum well layer 5, upper waveguide layer 6, and upper cover layer 7. The lower electrode layer 1, substrate layer 2, lower cover layer 3, lower waveguide layer 4, multi-quantum well layer 5, upper waveguide layer 6, and upper cover layer 7 have the same size along the arrangement direction of contact strip 901 and insulating strip 902, and are used for lateral mode selection control.

[0033] Contact strip 901 is an InGaAs contact strip that has undergone p-type modulation doping, with a p-type doping concentration greater than 1×10⁻⁶. 19 cm -3 Up to 2×10 19 cm -3 The size of the middle contact strip 901 along the arrangement direction is 0.5 micrometers to 1 micrometer. The size of the contact strips 901 on both sides of the middle contact strip 901 along the arrangement direction increases with the distance from the middle contact strip 901. The size of the contact strip 901 along the stacking direction is 0.2 micrometers to 0.4 micrometers.

[0034] The insulating strip 902 is a silicon oxide insulating strip or a silicon nitride insulating strip. An insulating strip 902 is provided between two adjacent contact strips 901. The size of the insulating strip 902 along the arrangement direction is 1 micrometer to 3 micrometers. The size of the insulating strip 902 along the stacking direction is the same as that of the contact strip 901. The size of each insulating strip 902 along the arrangement direction is the same.

[0035] The upper electrode layer 10 has a double-layer structure, which includes a titanium layer and a first gold layer stacked from bottom to top. The titanium layer has a size of 50nm~100nm along the stacking direction, and the first gold layer has a size of not less than 300nm along the stacking direction.

[0036] Ridge layer 8 is an InP ridge layer or an AlGaAs ridge layer with p-type modulation doping, and the p-type doping concentration is greater than 1 × 10⁻⁶. 18 cm -3 Up to 8×10 18 cm -3 The dimensions of the ridge layer 8 along the stacking direction are 0.4 micrometers to 0.6 micrometers.

[0037] Top capping layer 7 is an InP top capping layer or an AlGaAs top capping layer with p-type modulation doping concentration of 1×10⁻⁶. 18 cm -3 Up to 8×10 18 cm -3 The gradient is achieved by the top cover layer 7, which has dimensions ranging from 0.8 micrometers to 1 micrometer along the stacking direction.

[0038] The upper waveguide layer 6 is an InGaAsP waveguide layer or an AlGaInAs waveguide layer, with an unintentional doping concentration of less than 2 × 10⁶. 17 cm -3 The upper waveguide layer 6 has a size of 0.2 micrometers to 0.8 micrometers along the stacking direction. The refractive index of the upper waveguide layer 6 gradually decreases from bottom to top, and the minimum refractive index value is not lower than 3.0.

[0039] The multiple quantum well layer 5 is an InGaAsP multiple quantum well layer or an AlGaInAs multiple quantum well layer. The dimensions of the multiple quantum well layer 5 along the stacking direction are 10nm~100nm. The multiple quantum well layer 5 includes 1-10 quantum wells. The thickness of the well layer is 4nm~10nm, and the thickness of the barrier layer is 4nm~10nm. The barrier confinement structure of the multiple quantum well layer 5 adopts double barrier layer confinement. The electronic band step between the first barrier layer and the adjacent well layer is greater than 0.3 electron volts, and the hole band step between the second barrier layer and the adjacent well layer is greater than 0.3 electron volts. The thickness of the double barrier layer of the multiple quantum well layer 5 is different. The multiple quantum well layer 5 has a high barrier difference, which can improve the high temperature characteristics of semiconductor laser structures that can reduce hole burning effect.

[0040] The lower waveguide layer 4 is an InGaAsP waveguide layer or an AlGaInAs waveguide layer, with an unintentional doping concentration of less than 2 × 10⁻⁶. 17 cm -3 The dimensions of the lower waveguide layer 4 along the stacking direction are 0.2 micrometers to 0.8 micrometers. The refractive index of the lower waveguide layer 4 gradually increases from bottom to top, and the minimum refractive index value is not lower than 3.6.

[0041] Lower capping layer 3 is an InP lower capping layer or an AlGaAs lower capping layer with N-type modulation doping, and the N-type doping concentration is 1×10⁻⁶. 18 cm -3 The dimensions of the lower cover layer 3 along the stacking direction are 1.0 micrometers to 1.5 micrometers.

[0042] The substrate 2 is an N-type modulated doped GaAs substrate or an InP substrate, and the size of the substrate 2 along the stacking direction is 70 micrometers to 90 micrometers.

[0043] Furthermore, a buffer layer is disposed between the substrate layer 2 and the lower capping layer 3. The buffer layer is an N-type modulated doped GaAs buffer layer with a dimension of 0.4 μm to 1 μm along the stacking direction and an N-type doping concentration of 5 × 10⁻⁶. 17 cm -3 Up to 1×10 18 cm -3 .

[0044] The lower electrode layer 1 consists of a second gold layer and a gold-germanium-nickel layer stacked from bottom to top. The size of the second gold layer along the stacking direction is not less than 1000 nm, and the surface of the second gold layer is covered with pits. The period size of the pits is 5 μm to 10 μm, and the depth is 200 nm to 600 nm. The surface particle size of the second gold layer is 8000 mesh to 10000 mesh, and the size of the gold-germanium-nickel layer along the stacking direction is 50 nm to 100 nm.

[0045] The aforementioned semiconductor laser structure, which reduces the hole-burning effect, utilizes MOCVD equipment, with TMGa, TMAl, and TMIn as MO sources. Doping sources include SiH4 and CF4, and specialty gases are AsH3 and PH3. Specifically, a GaAs buffer layer is grown on the GaAs substrate 2 at 710°C, and an N-AlGaAs capping layer 3 with a thickness of 1.0 μm to 1.5 μm is grown on the N-GaAs buffer layer at 710°C, with an N-type doping concentration of 1 × 10⁻⁶. 18 cm -3 .

[0046] A lower waveguide layer 4 is grown on the lower capping layer 3 at 710℃. The material is InGaAsP or AlGaInAs, and the size along the stacking direction is 0.2 μm to 0.8 μm. The unintentional doping concentration is less than 2 × 10⁻⁶. 17 cm -3 The refractive index of the lower waveguide layer 4 is gradually distributed, increasing from bottom to top, and satisfies the raised cosine distribution, with the highest refractive index not exceeding 3.6.

[0047] A multi-quantum well layer 5 is grown on the lower waveguide layer 4 at 700℃. The material of the multi-quantum well layer 5 is InGaAsP or AlGaInAs, and the thickness is 10nm~100nm. The unintentional doping concentration is less than 2×10⁻⁶. 17 cm -3 .

[0048] A waveguide layer 6 is grown on the multi-quantum well layer 5 at 700℃. The material of the upper waveguide layer 6 is InGaAsP or AlGaInAs, and its size along the stacking direction is 0.2 μm-0.8 μm. The unintentional doping concentration is less than 2 × 10⁻⁶. 17 cm -3The refractive index of the upper waveguide layer 6 is gradually distributed, decreasing from bottom to top, and satisfies a reduced cosine distribution, with the lowest refractive index value not lower than 3.0.

[0049] A capping layer 7 and a ridge layer 8 are grown on the upper waveguide layer 6 at 700℃. The materials of the capping layer 7 and the ridge layer 8 are InP or AlGaAs. The total size of the capping layer 7 and the ridge layer 8 along the stacking direction is 1.2 μm to 1.6 μm. Both the capping layer 7 and the ridge layer 8 are P-type modulated doped with a P-type doping concentration of 1 × 10⁻⁶. 18 cm -3 Up to 8×10 18 cm -3 Gradual change.

[0050] A contact layer is grown at 710°C on the unetched ridge layer 8. The contact layer is made of InGaAs and has dimensions of 0.2 μm to 0.4 μm along the stacking direction. The contact layer is P-type modulated doped with a P-type doping concentration greater than 1 × 10⁻⁶. 19 cm -3 Up to 2×10 19 cm -3 .

[0051] Then, the top cover layer 7 and the contact layer are patterned. The ridge layer 8 is patterned using photolithography and etching, with a depth of 0.4 μm to 0.6 μm. The contact layer is patterned using photolithography and etching, such as contact strips 901 which are strips distributed according to a certain pattern. The contact strip 901 in the middle has the smallest dimension along the arrangement direction. The dimensions of the contact strips 901 at both ends gradually increase along the arrangement direction with the increase of the distance from the middle contact strip 901, with the smallest width being 1 μm and the middle being zero. The gradual width of the contact strips 901 satisfies various relationships such as the e-exponential curve and raised cosine. An insulating strip 902 is filled between two adjacent contact strips 901. The insulating strip 902 is made of silicon oxide or silicon nitride, with the same height as the contact strips 901, and a dimension of 1 μm to 3 μm along the arrangement direction.

[0052] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0053] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A semiconductor laser structure capable of reducing the burning hole effect, characterized in that, The device comprises, from bottom to top, a lower electrode layer, a substrate layer, a lower capping layer, a lower waveguide layer, a multiple quantum well layer, an upper waveguide layer, an upper capping layer, a ridge layer, a patterned contact layer, and an upper electrode layer. The patterned contact layer is composed of multiple contact strips and multiple insulating strips arranged alternately. The size of the contact strips along the arrangement direction gradually increases from the middle contact strip to the contact strips at both ends of the arrangement direction. The size of each insulating strip is equal along the arrangement direction.

2. The semiconductor laser structure capable of reducing the burn-through effect according to claim 1, wherein, Along the arrangement direction of the contact strips and the insulating strips, the dimensions of the ridge layer, the patterned contact layer, and the upper electrode layer are smaller than the dimensions of the lower electrode layer, the substrate layer, the lower cover layer, the lower waveguide layer, the multiple quantum well layer, the upper waveguide layer, and the upper cover layer.

3. The semiconductor laser structure capable of reducing the burn-through effect according to claim 1, wherein, The contact strip is an InGaAs contact strip that has undergone P-type modulation doping. The size of the middle contact strip along the arrangement direction is 0.5 micrometers to 1 micrometer, and the size of the contact strip along the stacking direction is 0.2 micrometers to 0.4 micrometers.

4. The semiconductor laser structure capable of reducing the burn-through effect according to claim 2, wherein, The insulating strip is a silicon oxide insulating strip or a silicon nitride insulating strip. The size of the insulating strip along the arrangement direction is 1 micrometer to 3 micrometers. The size of the insulating strip along the stacking direction is the same as that of the contact strip.

5. The semiconductor laser structure capable of reducing the burn-through effect according to any one of claims 1-4, wherein the semiconductor laser structure further comprises a first cladding layer, a second cladding layer, and a waveguide layer between the first cladding layer and the second cladding layer. The upper electrode layer includes a titanium layer and a first gold layer stacked from bottom to top. The titanium layer has a size of 50nm to 100nm along the stacking direction, and the first gold layer has a size of not less than 300nm along the stacking direction.

6. The semiconductor laser structure with reduced hole-burning effect according to any one of claims 1-4, characterized in that, The ridge layer is an InP ridge layer or an AlGaAs ridge layer that has undergone P-type modulation doping, and the size of the ridge layer along the stacking direction is 0.4 micrometers to 0.6 micrometers.

7. The semiconductor laser structure with reduced hole-burning effect according to any one of claims 1-4, characterized in that, The capping layer is an InP capping layer or an AlGaAs capping layer that has undergone P-type modulation doping, and the size of the capping layer along the stacking direction is 0.8 micrometers to 1 micrometer.

8. The semiconductor laser structure with reduced hole-burning effect according to any one of claims 1-4, characterized in that, The upper waveguide layer is an InGaAsP waveguide layer or an AlGaInAs waveguide layer. The size of the upper waveguide layer along the stacking direction is 0.2 micrometers to 0.8 micrometers. The refractive index of the upper waveguide layer gradually decreases from bottom to top, and the minimum refractive index value is not lower than 3.

0.

9. The semiconductor laser structure with reduced hole-burning effect according to any one of claims 1-4, characterized in that, The multiple quantum well layer is an InGaAsP multiple quantum well layer or an AlGaInAs multiple quantum well layer. The dimensions of the multiple quantum well layer along the stacking direction are 10nm~100nm. The multiple quantum well layer includes 1-10 quantum wells. The thickness of the well layer is 4nm~10nm, and the thickness of the barrier layer is 4nm~10nm. The barrier confinement structure of the multiple quantum well layer adopts double barrier layer confinement. The electronic band step between the first barrier layer and the adjacent well layer is greater than 0.3 electron volts, and the hole band step between the second barrier layer and the adjacent well layer is greater than 0.3 electron volts. The thickness of the double barrier layer of the multiple quantum well layer is different.

10. The semiconductor laser structure with reduced hole-burning effect according to any one of claims 1-4, characterized in that, The lower waveguide layer is an InGaAsP waveguide layer or an AlGaInAs waveguide layer. The size of the lower waveguide layer along the stacking direction is 0.2 micrometers to 0.8 micrometers. The refractive index of the lower waveguide layer gradually increases from bottom to top, and the minimum refractive index value is not lower than 3.

6.

11. The semiconductor laser structure with reduced hole-burning effect according to any one of claims 1-4, characterized in that, The lower capping layer is an InP lower capping layer or an AlGaAs lower capping layer that has undergone N-type modulation doping, and the size of the lower capping layer along the stacking direction is 1.0 micrometer to 1.5 micrometer.

12. The semiconductor laser structure with reduced hole-burning effect according to any one of claims 1-4, characterized in that, The substrate is an N-type modulated doped GaAs substrate or an InP substrate, and the size of the substrate along the stacking direction is 70 micrometers to 90 micrometers.

13. The semiconductor laser structure with reduced hole-burning effect according to any one of claims 1-4, characterized in that, The lower electrode layer consists of a second gold layer and a gold-germanium-nickel layer stacked from bottom to top. The second gold layer has a dimension of not less than 1000 nm along the stacking direction, and its surface is covered with pits. The period size of the pits is 5 μm to 10 μm, and the depth is 200 nm to 600 nm. The surface particle size of the second gold layer is 8000 mesh to 10000 mesh, and the dimension of the gold-germanium-nickel layer along the stacking direction is 50 nm to 100 nm.

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