Semiconductor laser and manufacturing method therefor

Abstract

Embodiments of the present application relate to the technical field of semiconductor lasers, and provide a semiconductor laser and a manufacturing method therefor, which are used to mitigate the problem of chirp in semiconductor lasers. The semiconductor laser comprises: a substrate; a ridge waveguide which is arranged on the substrate and extends in a first direction of the substrate; and a grating which is arranged at a top portion of the ridge waveguide. The grating comprises first regions and second regions periodically arranged in the first direction, each first region comprises a semiconductor material, each second region comprises an insulating dielectric material, and the refractive index of the insulating dielectric material is greater than the refractive index of the semiconductor material.

Description

Semiconductor laser and manufacturing method thereof

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on October 13, 2023, with application number 202311330374.5 and application name “A semiconductor laser and its manufacturing method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of semiconductor lasers, and in particular to a semiconductor laser and a method for manufacturing the same. Background Art

[0003] With the increasing demand for high-bitrate services such as high-definition video and high-performance edge computing on the user side in recent years, the International Telecommunication Union-World Telecommunication Standards Assembly has successively announced relevant specifications for 10G asymmetric passive optical networks and 10G symmetric passive optical networks. These relevant specifications both put forward low chirp requirements for semiconductor lasers.

[0004] Summary of the Invention

[0005] Embodiments of the present application provide a semiconductor laser and a method for manufacturing the same, for reducing the chirp problem of the semiconductor laser.

[0006] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0007] In a first aspect, a semiconductor laser is provided. The semiconductor laser comprises: a substrate; a ridge waveguide disposed on the substrate and extending along a first direction of the substrate; and a grating disposed on top of the ridge waveguide. The grating comprises a first region and a second region periodically arranged along the first direction, the first region comprising a semiconductor material, and the second region comprising an insulating dielectric material, wherein the refractive index of the insulating dielectric material is greater than the refractive index of the semiconductor material.

[0008] In this implementation, a grating is disposed on top of a ridge waveguide, and a first region and a second region are periodically arranged in the grating, wherein the first region comprises a semiconductor material and the second region comprises an insulating dielectric material, and the refractive index of the insulating dielectric material is greater than the refractive index of the semiconductor material. In this way, when the semiconductor laser is operating, the operating current can be injected from the first region instead of from the second region, thereby forming a surface inversion gain coupling grating on top of the ridge waveguide. The inversion gain coupling grating adjusts the phase distribution of light by introducing a phase offset, correcting the wavefront distortion of light, such as the wavefront distortion caused by the chirp effect, thereby reducing the chirp problem of the semiconductor laser. In addition, the inversion gain coupling grating only requires epitaxy once during the formation process, thereby improving the yield of the semiconductor laser and effectively reducing the cost of the semiconductor laser.

[0009] In some possible implementations, the ridge waveguide includes a plurality of sub-waveguides arranged along the first direction, and the plurality of sub-waveguides are separated by insulating dielectric materials.

[0010] In some possible implementations, the sub-waveguides correspond one-to-one to the first region of the grating, and the insulating dielectric material between the plurality of sub-waveguides is integrally formed with the second region of the grating.

[0011] In some possible implementations, the base includes a substrate and an active layer disposed on the substrate. The active layer can provide support for amplification, modulation, and stability of optical signals and improve light coupling efficiency.

[0012] In some possible implementations, the average refractive index of the active layer is greater than the refractive index of the insulating filling region, thereby further improving the performance of the semiconductor laser.

[0013] In some possible implementations, a first waveguide confinement layer is further provided between the substrate and the active layer.

[0014] In some possible implementations, the semiconductor laser further includes a first electrode, which is disposed on the grating, and a projection of the grating on the substrate at least partially covers a projection of the first electrode on the substrate.

[0015] In some possible implementations, the semiconductor laser further includes a second electrode, which is disposed on a side of the substrate away from the ridge waveguide.

[0016] In some possible implementations, the substrate includes a first surface and a second surface opposite the first surface, wherein the first surface and the second surface both extend perpendicular to the first direction of the substrate. The semiconductor laser further includes a highly reflective dielectric film layer covering the first surface of the substrate. By providing the highly reflective dielectric film layer in the semiconductor laser, the output power and performance of the semiconductor laser can be effectively enhanced, improving light utilization efficiency.

[0017] In some possible implementations, the semiconductor laser further includes an anti-reflection dielectric film layer covering the second surface of the substrate. The anti-reflection dielectric film layer in the semiconductor laser can modify the refraction and interference of light to reduce reflection, thereby improving transmittance and semiconductor laser performance.

[0018] In a second aspect, a method for manufacturing a semiconductor laser is provided, comprising: forming a substrate; forming a stacked ridge waveguide and a grating on the substrate, wherein the ridge waveguide extends along a first direction of the substrate; the grating comprises a first region and a second region periodically arranged along the first direction, the first region comprising a semiconductor material, the second region comprising an insulating dielectric material, and the refractive index of the insulating dielectric material being greater than the refractive index of the semiconductor material.

[0019] In some possible implementations, forming a stacked ridge waveguide and a grating on the substrate includes: forming a waveguide layer on the substrate;

[0020] An ohmic contact layer is formed on the waveguide layer; the waveguide layer and the ohmic contact layer are periodically etched to form periodically arranged openings in the waveguide layer and the ohmic contact layer, and the openings penetrate the waveguide layer and the ohmic contact layer; an insulating dielectric material is deposited in the openings to form a stacked ridge waveguide and a grating, wherein the ridge waveguide includes a plurality of sub-waveguides, and the plurality of sub-waveguides are separated by the insulating dielectric material.

[0021] In some possible implementations, forming the base includes: forming a substrate; and forming an active layer on the substrate.

[0022] In some possible implementations, before forming the active layer, forming the base further includes: forming a first waveguide confinement layer on the substrate.

[0023] In some possible implementations, forming the substrate further includes: forming a second waveguide confinement layer on the active layer.

[0024] In some possible implementations, the forming method further includes: depositing a first metal material on the grating to form a first electrode, and a projection of the grating on the substrate covers a projection of the first electrode on the substrate.

[0025] In some possible implementations, the formation method further includes: thinning the substrate; and depositing a second metal material on a side of the substrate away from the ridge waveguide to form a second electrode.

[0026] Among them, the technical effects brought about by any possible implementation method of the second aspect can refer to the technical effects brought about by different implementation methods of the above-mentioned first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] FIG1 is a schematic structural diagram of a semiconductor laser provided in an embodiment of the present application;

[0029] FIG2 is a schematic flow chart of a method for manufacturing a semiconductor laser according to an embodiment of the present application;

[0030] 3 to 16 are schematic structural diagrams of various stages in the manufacturing process of the semiconductor laser provided in the embodiments of the present application. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0032] In the following, the terms "first," "second," etc. are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the quantity of the technical features indicated. Therefore, a feature specified as "first," "second," etc. may explicitly or implicitly include one or more of the features.

[0033] Additionally, for ease of description, spatially relative terms such as "bottom," "below," "beneath," "above," and the like may be used herein to describe the relationship of one component or feature to another component, or function as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein should be interpreted accordingly.

[0034] Fiber-to-the-home (FTTH) gigabit-capable passive optical networks (GPON) are the current mainstream broadband access network model. However, with increasing user demand for high-bitrate services such as high-definition video and high-performance edge computing, GPON networking is no longer able to meet the scale and requirements of future high-bandwidth services. To address this growing demand for transmission speeds, the International Telecommunication Union-World Telecommunication Standards Assembly (ITU-T) has released specifications for 10G asymmetric passive optical networks (XG-PON) and 10G symmetric passive optical networks (XGS-PON). Compared with the GPON networking mode, the downlink transmission rate of XG(S)-PON has increased from the original 2.5Gb / s to 10Gb / s. At the same time, in order to be compatible with the previous transmission wavelength, XG(S)-PON newly stipulates 1577nm in the L band as the center wavelength of its downlink. Compared with the semiconductor laser with a center wavelength of 1490nm, the light emitted by the semiconductor laser with a center wavelength of 1577nm has a larger dispersion in ordinary single-mode (G652) optical fiber, which in turn puts forward the requirement of low chirp for the semiconductor laser.

[0035] Semiconductor lasers are divided into electro-absorption modulated lasers (EML) and direct modulated lasers (DML).

[0036] The operating principle of a directly modulated laser (DML) is that by injecting current into a semiconductor material, photons are generated and amplified to form a laser. As the current changes, the intensity of the laser's light output also changes accordingly. This directly modulated laser offers advantages such as a simple structure, high energy efficiency, and high output power. However, the current modulation process causes a change in the refractive index of the active region, modulating the phase of the light and causing frequency chirp. This frequency chirp becomes increasingly pronounced as the modulation rate increases, limiting transmission distance.

[0037] To improve the frequency chirp problem in directly modulated lasers (DMLs), two approaches can be used. The first is to reduce the device's instantaneous chirp by lowering the extinction ratio during signal modulation. However, this will affect other DML performance, such as increasing the bit error rate (BER), which in turn degrades the DML's performance. To address this, a narrowband filter can be connected to the DML to utilize the adiabatic chirp effect to reduce the "0" signal amplitude, thereby increasing the extinction ratio. This reduces the chirp problem while ensuring the extinction ratio meets the required level. The second approach is to employ chirp management techniques to reduce the DML's chirp, such as pre-chirping techniques based on digital signal processing chips and chirp-managed lasers. However, both approaches increase the complexity, size, and cost of the DML.

[0038] An electroabsorption modulated laser consists of a laser and an electroabsorption modulator (EAM). An EAM is a device that modulates the absorption properties of a material by applying an external voltage. When voltage is applied to the EAM, it changes the optical bandgap of the absorbing material, thereby controlling the laser's output intensity.

[0039] However, the electro-absorption modulated laser has a complex structure, requiring the laser and the electro-absorption modulator to be designed and optimized separately. At the same time, reflections at the output end face of the electro-absorption modulator can cause severe crosstalk between the laser and the electro-absorption modulator, resulting in a complex integration process. As a result, the electro-absorption modulated laser has problems with low reliability and low yield, which also makes the electro-absorption modulated laser very expensive. In addition, the inherent insertion loss of the electro-absorption modulated laser results in very low output optical power, making it difficult to meet the ITU-T requirements for light sources for the XG(S)-PON system. Therefore, in practical applications, it is necessary to improve the sensitivity performance of the receiver in the link or integrate a semiconductor optical amplifier to meet the specified power budget. However, this will further increase the cost of the XG(S)-PON system (optical line terminal).

[0040] In addition, before making a grating, whether it is a directly modulated laser or an electro-absorption modulated laser, it is necessary to first grow semiconductor materials on the substrate to form a base (primary epitaxy); after the base is made, at least one more epitaxy is performed to form the grating (secondary epitaxy). The grating is generated by controlling the growth conditions of the material and the formation of the periodic structure. This epitaxy needs to be precisely controlled to obtain the required grating parameters, such as period, depth, and refractive index difference. After the epitaxy is completed, other subsequent processes are required to produce the corresponding semiconductor laser. The epitaxy process requires a large amount of raw materials, and the equipment is expensive, so this process is relatively expensive. Moreover, since the heating effect of the epitaxy will cause the grating to deform, in order to ensure the quality of the grating, more stringent process requirements are required for the secondary epitaxy, and the production cost of the secondary epitaxy is higher than that of the primary epitaxy. Therefore, the production cost is high.

[0041] Therefore, an embodiment of the present application further provides a semiconductor laser. FIG1 shows a schematic structural diagram of a semiconductor laser provided in an embodiment of the present application, comprising: a substrate 100, a ridge waveguide 210, and a grating 220. The ridge waveguide 210 is disposed on the substrate 100 and extends along a first direction of the substrate 100; the grating 220 is disposed on top of the ridge waveguide 210, wherein the grating 220 comprises a first region 221 and a second region 222 periodically arranged along the first direction. The first region 221 comprises a semiconductor material, and the second region 222 comprises an insulating dielectric material, wherein the refractive index of the insulating dielectric material is greater than the refractive index of the semiconductor material.

[0042] In a specific example, as shown in FIG2 , forming the above-mentioned semiconductor laser includes: S10: forming a substrate 100; S20: forming a stacked ridge waveguide 210 and a grating 220 on the substrate 100, wherein the ridge waveguide 210 extends along a first direction of the substrate 100; the grating 220 includes a first region 221 and a second region 222 periodically arranged along the first direction, the first region 221 includes a semiconductor material, and the second region 222 includes an insulating dielectric material, and the refractive index of the insulating dielectric material is greater than the refractive index of the semiconductor material.

[0043] In this embodiment, the grating 220 is set on the top of the ridge waveguide, and a first region 221 and a second region 222 are periodically arranged in the grating 220, wherein the first region 221 includes a semiconductor material and the second region 222 includes an insulating dielectric material. The refractive index of the insulating dielectric material is greater than the refractive index of the semiconductor material. In this way, when the semiconductor laser is working, the working current can be injected from the first region 221 instead of from the second region 222, thereby forming a surface inversion gain coupling grating on the top of the ridge waveguide 210. The inversion gain coupling grating is introduced by Phase shift is used to adjust the phase distribution of light and correct wavefront distortion of light, such as the wavefront distortion caused by the chirp effect, thereby reducing the chirp problem of semiconductor lasers and laying the foundation for the application of DFB-DML in XG(S)-PON systems. In addition, the refractive index of the insulating dielectric material filled in the second region can be adjusted according to actual needs, which increases the process tolerance of semiconductor laser preparation and thus improves the yield of semiconductor lasers. In addition, the inverted gain-coupled grating only requires epitaxy once during its formation, effectively reducing the cost of semiconductor lasers.

[0044] The following takes an AlGaInAs / InP surface inverse gain coupled DFB-DML semiconductor laser with a wavelength of 1577 nm as an example to illustrate the manufacturing process of the semiconductor laser and the device structure formed during the manufacturing process.

[0045] S10: forming a substrate 100. This step further includes:

[0046] S11: forming a substrate 101.

[0047] As shown in FIG3 , the semiconductor laser includes a substrate 101. Exemplarily, the substrate 101 is a single-layer structure. For example, the substrate 101 is a heavily doped n-type InP substrate 101. Alternatively, exemplary, the substrate 101 is a multi-layer structure. For example, a buffer layer is further formed on the heavily doped n-type InP substrate 101. The buffer layer may be an n-type InP buffer layer with a thickness of 500 nm and a doping concentration of 1.5×10 18 cm -3 .

[0048] S12 : forming a first waveguide confinement layer 102 on the substrate 101 .

[0049] As shown in FIG4 , the semiconductor laser further includes a first waveguide confinement layer 102 formed on the substrate 101. Exemplarily, the first waveguide confinement layer 102 is a multi-layer structure, for example, a three-layer structure, namely, the first waveguide confinement layer 102 comprises, from bottom to top, a first sub-waveguide confinement layer, a second sub-waveguide confinement layer, and a third sub-waveguide confinement layer. The thickness of the first sub-waveguide confinement layer can be 10 nm, the fluorescence wavelength can be 968 nm to 841 nm, and the doping concentration of aluminum gallium indium arsenide (AlGaInAs) can be 1.5×10 18 cm -3 The thickness of the second sub-waveguide confinement layer can be 40 nm, the fluorescence wavelength is 841 nm, and the doping concentration of aluminum indium arsenide (AlInAs) is 1.5×10 18 cm -3 The thickness of the third sub-waveguide limiting layer can be 50nm, the fluorescence wavelength is 841nm-1200nm, and the doping concentration of AlGaInAs is 0.5×10 18 cm -3 It is understood that, in other optional examples, the first waveguide limiting layer 102 may also be a single-layer structure. When the number of layers of the first waveguide limiting layer 102 changes, the component ratio of each sub-waveguide limiting layer in the first waveguide limiting layer 102 should also change accordingly.

[0050] S13 : forming an active layer 103 on the first waveguide confinement layer 102 .

[0051] As shown in FIG5 , the semiconductor laser further includes an active layer 103 formed on the first waveguide confinement layer 102. The active layer 103 can provide support for the amplification, modulation, and stability of the optical signal and improve the optical coupling efficiency. Exemplarily, the active layer 103 is composed of quantum wells and barriers, wherein the quantum wells and barriers are preferably composed of compressive strain quantum wells and tensile strain barriers, and the quantum well materials are indium gallium arsenide phosphide multiple quantum wells, or aluminum gallium indium arsenide multiple quantum wells, or aluminum gallium arsenide multiple quantum wells. Exemplarily, the active layer 103 includes 6 well layers and 7 barrier layers, wherein: the well width is 6 nm, undoped, ~1.3% compressive strain, and the optical fluorescence wavelength is 1803 nm; the barrier width is 6 nm, undoped, ~0.5% tensile strain, and the optical fluorescence wavelength is 1299 nm.

[0052] S14 : forming a second waveguide confinement layer 104 on the active layer 103 .

[0053] As shown in FIG6 , the semiconductor laser further includes a second waveguide confinement layer 104 formed on the active layer 103. Exemplarily, the second waveguide confinement layer 104 is a multi-layer structure. For example, the second waveguide confinement layer 104 is a four-layer structure, i.e., the second waveguide confinement layer 104 comprises, from bottom to top, a fourth sub-waveguide confinement layer, a fifth sub-waveguide confinement layer, a sixth sub-waveguide confinement layer, and a seventh sub-waveguide confinement layer. The thickness of the fourth sub-waveguide confinement layer can be 50 nm, the fluorescence wavelength can be 1200 nm to 841 nm, and the doping concentration of AlGaInAs can be 0.3×10 18 cm -3 The thickness of the fifth sub-waveguide confinement layer can be 30 nm, the fluorescence wavelength is 841 nm, and the doping concentration of AlInAs is 0.5×10 18 cm -3 The thickness of the limiting stop layer of the sixth sub-waveguide 211 can be 10 nm, the fluorescence wavelength is 841 nm-968 nm, and the doping concentration of AlGaInAs is 0.5×10 18 cm -3 ); The fluorescence wavelength of the seventh sub-waveguide confinement layer is 1100 nm, and the doping concentration of p-type InGaAsP is 0.5×10 18 cm -3 It is understood that, in other optional examples, the second waveguide limiting layer 104 may also be a single-layer structure. When the number of layers of the second waveguide limiting layer 104 changes, the component ratio of each sub-waveguide limiting layer in the second waveguide limiting layer 104 should also change accordingly.

[0054] It is understandable that the first waveguide limiting layer 102 , the active layer 103 and the second waveguide limiting layer 104 can be formed simultaneously through a single epitaxial process, thereby reducing the manufacturing cost of the semiconductor laser.

[0055] S20: forming a stacked ridge waveguide 210 and a grating 220 on a substrate. This step further includes:

[0056] As shown in FIG7 , S21: forming a waveguide layer 105 on the substrate. For example, the thickness of the waveguide layer 105 can be 1750 nm, and the gradient doping concentration is 0.5×10 18 cm -3 -2×10 18 cm -3 .

[0057] As shown in FIG. 8 , S22 : forming an ohmic contact layer 106 on the waveguide layer 105 .

[0058] Exemplarily, the ohmic contact layer 106 is a multi-layer structure, for example, the ohmic contact layer 106 is a three-layer structure, that is, the ohmic contact layer 106 is sequentially composed of: a first sub-ohmic contact layer, a second sub-ohmic contact layer, and a third sub-ohmic contact layer from bottom to top. The thickness of the first sub-ohmic contact layer can be 25 nm, the fluorescence wavelength is 1250 nm, and the doping concentration of the heavily doped p-type InGaAsP is 3×10 18 cm -3 The thickness of the second sub-ohmic contact layer can be 25 nm, the fluorescence wavelength is 1500 nm, and the doping concentration of the heavily doped p-type InGaAsP is 3×10 18 cm -3 The thickness of the third sub-ohmic contact layer can be 150 nm, the fluorescence wavelength can be 1654 nm, and the doping concentration of the heavily doped p-type InGaAs layer can be 3×10 19 cm -3 .

[0059] As shown in FIG. 9 , S23 : forming a dielectric layer 107 on the ohmic contact layer.

[0060] The dielectric layer 107 may be made of silicon oxide, silicon nitride, silicon oxynitride, or other suitable materials. The dielectric layer 107 is formed on the ohmic contact layer 106 by a deposition process, such as chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), high-density plasma chemical vapor deposition (HDPCVD), metal organic chemical vapor deposition (MOCVD), or plasma enhanced chemical vapor deposition (PECVD).

[0061] In some optional examples, before forming the dielectric layer 107, the formed semiconductor laser needs to be cleaned, for example, by sequentially cleaning the semiconductor laser with trichloroethylene, acetone, ethanol, and deionized water, and then baking it at 120°C for 2 minutes to remove impurities remaining on the surface of the ohmic contact layer 106 to prevent the impurities from affecting the performance of the semiconductor laser.

[0062] As shown in FIG. 10 , S24 : forming a photoresist layer 108 on the dielectric layer 107 , and patterning the photoresist layer 108 through a patterning process.

[0063] The patterning process includes a photolithography process and an etching process. The photolithography process includes photoresist coating (e.g., spin coating), soft baking, mask alignment, exposure, post-exposure baking, developing photoresist, rinsing and drying (e.g., hard baking). The etching process includes a dry etching process or a wet etching process. The grating pattern and the ridge waveguide 210 pattern can be made on the photoresist layer 108 by the etching process. Wherein, the grating 220 can be a first-order or high-order grating. Exemplarily, when the grating 220 is a first-order grating, the period range of the grating 220 can be 230-250nm, the duty cycle of the grating 220 can be 0.5-0.6, and the width of the grating 220 can be 1um-3um, and the corresponding ridge waveguide width 1.5um-5um high-order grating period range and duty cycle can be adjusted according to actual conditions, and the embodiment of the application is not limited.

[0064] S25: The patterned photoresist layer 108 is used as a mask to pattern the dielectric layer 107. For example, a dry etching process can be used to pattern the dielectric layer 107. The dry etching process includes using a fluorine-based etchant gas such as SF6, CxFy, NF3, or a combination thereof. After forming the patterned dielectric layer 107, the patterned photoresist layer 108 should be removed.

[0065] S26 : using the patterned dielectric layer 107 as a mask to pattern the waveguide layer 105 and the ohmic contact layer 106 .

[0066] In this embodiment, referring to the schematic structural diagram of the semiconductor laser shown in FIG11 , FIG11 ( 2 ) is a cross-sectional view of FIG11 ( 1 ) taken along the AA' plane, and FIG11 ( 3 ) is a cross-sectional view of FIG11 ( 1 ) taken along the BB' plane. By transferring the grating pattern and the ridge waveguide 210 pattern from the dielectric layer 107 to the waveguide layer 105 and the ohmic contact layer 106 , a plurality of openings 223 are formed that penetrate the waveguide layer 105 and the ohmic contact layer 106 . The plurality of openings 223 divide the waveguide layer 105 into a plurality of sub-waveguides 211 . The plurality of sub-waveguides 211 are arranged along a first direction of the substrate 100 , with adjacent sub-waveguides 211 separated by the openings 223 . The unetched ohmic contact layer 106 constitutes the first region 221 of the grating 220 .

[0067] In an optional example, a wet etching process or a dry etching process can be used to form openings in the waveguide layer 105 and the ohmic contact layer 106. For example, a wet etching process can be used with a phosphoric acid and hydrobromic acid etching solution in a ratio of 1:1. After standing at 45°C for 5 minutes, the semiconductor laser is placed in the etching solution and etched for 4-8 minutes. Since the etching rate ratio of the third sub-ohmic contact layer and the waveguide layer 105 is different, the third sub-ohmic contact layer can be used as an etch stop layer when patterning the waveguide layer 105 and the ohmic contact layer 106 using a wet etching process. A dry etching process can be used using inductively coupled plasma (ICP) etching with Cl2, CH4, H2, and Ar as reaction gases to etch the ohmic contact layer 106 and the waveguide layer 105. The etching is stopped in time using the instrument endpoint monitoring function. After patterning the waveguide layer 105 and the ohmic contact layer 106, the patterned dielectric layer 107 is removed.

[0068] S27: depositing an insulating dielectric material in the opening to form the second region 222 of the grating 220. For example, the insulating dielectric material may be silicon (Si) or silicon oxynitride.

[0069] In this embodiment, referring to the schematic structural diagram of the semiconductor laser shown in FIG12, FIG12 (ii) is a cross-sectional view of FIG12 (i) on the AA' plane; FIG12 (iii) is a cross-sectional view of FIG12 (i) on the BB' plane. By depositing an insulating dielectric material in the opening 223, the plurality of sub-waveguides 211 are separated by the insulating dielectric material, and a plurality of second regions 222 are formed in the grating 220. The first region 221 and the second region 222 of the grating 220 are periodically arranged along the first direction of the substrate 100. The refractive index of the insulating dielectric material in the second region 222 is greater than the refractive index of the semiconductor material in the first region 221. Thus, the semiconductor laser When the device is working, the operating current can be injected from the first region 221 of the grating 220 instead of from the second region 222, thereby forming a surface inverted gain coupling grating on the top of the waveguide. The inverted gain coupling grating adjusts the phase distribution of light by introducing a phase offset and corrects the wavefront distortion of light, such as the wavefront distortion caused by the chirp effect, thereby reducing the chirp problem of the semiconductor laser. In addition, the refractive index of the insulating dielectric material filled in the second region can be adjusted according to actual needs, thereby increasing the process tolerance of the semiconductor laser preparation and improving the yield of the semiconductor laser. In addition, the inverted gain coupling grating only requires epitaxy once during the formation process, effectively reducing the cost of the semiconductor laser.

[0070] In some optional embodiments, the average refractive index of the active layer 103 is greater than the refractive index of the insulating dielectric material filled in the second region 222 of the grating 220 , so as to improve the performance of the semiconductor laser.

[0071] It should be noted that, in some optional examples, after depositing the insulating dielectric material, the surface of the grating 220 may be planarized. For example, a self-aligned photolithography method may be used to form a photoresist mask on the surface of the grating 220, and an etcher may be used to etch away the protruding insulating dielectric material on the surface of the grating 220, and remove the residual photoresist. If there are still protrusions on the surface of the grating 220, the previous step may be repeated to completely planarize the surface of the grating 220, or to planarize it to a degree that meets the requirements.

[0072] It should be noted that the number of ridge waveguides 210 can be adjusted according to actual applications and is not limited to one ridge waveguide 210. In some other optional embodiments, an array of ridge waveguides 210 is formed on the substrate, and a grating 220 is formed on each ridge waveguide 210.

[0073] S30 : forming an insulating layer 230 on the substrate 100 .

[0074] Referring to FIG13 , which illustrates the structure of a semiconductor laser, an insulating layer 230 is formed on a substrate 100 through a deposition process. Exemplarily, the insulating layer 230 is made of a photosensitive BCB material. The insulating layer 230 covers the grating 220 and the ridge waveguide 210. The insulating layer 230 is then thinned until its upper surface is flush with the top of the grating 220. This means that the thickness of the insulating layer 230 is equal to the combined thickness of the ridge waveguide 210 and the grating 220. Finally, the top of the grating 220 is observed under an optical microscope to ensure that the InGaAs material is uniformly white and bright, without any interference colors from the insulating layer 230.

[0075] It should be noted that when there are multiple ridge waveguides 210 on the substrate 100, a gap is provided in the insulating layer 230 between adjacent ridge waveguides 210. Exemplarily, the width of the gap is 50 μm, and the length of the gap is generally in the range of 100-1000 μm. The gap serves as a cutting path for dissociating the semiconductor laser, dissociating the substrate 100 into multiple semiconductor lasers including a single ridge waveguide 210.

[0076] It can be understood that the thickness of the insulating layer 230 is equal to the total thickness of the ridge waveguide 210 and the grating 220, which includes absolute equality and approximate equality, wherein the acceptable deviation range of approximate equality is, for example, that the height difference between the two can be less than or equal to 100 nm, and the spacing between the ridge waveguide 210 and the insulating layer 230 can be less than or equal to 1 μm.

[0077] Referring to FIG. 14 , which shows a schematic diagram of the structure of a semiconductor laser, FIG. 14 ( b ) is a cross-sectional view of FIG. 14 ( i ) taken along the AA′ plane. S40: Depositing a first metal material on the grating 220 to form a first electrode 240 , wherein the projection of the grating 220 on the substrate at least partially covers the projection of the first electrode 240 on the substrate. Exemplarily, the first electrode 240 is a P-type electrode, the first metal material is Ti, Pt, Au, or other metal materials, and the thickness of the first electrode 240 is 20-400 nm. The width of the first electrode 240 is equal to the width of the ridge waveguide 210 . In some optional embodiments, an electrode pad 241 and a connecting structure 242 connecting the first electrode 240 to the electrode pad may also be formed simultaneously with the formation of the first electrode 240 . The electrode pad 241 may be a circular pad with a diameter of 100 μm. The distance between the circular pad and the ridge waveguide 210 may be less than or equal to 20 μm. The connecting structure 242 may be a rectangular structure with a width of 20 μm.

[0078] It can be understood that the width of the first electrode 240 being equal to the width of the ridge waveguide 210 includes being absolutely equal and being approximately equal. Within the acceptable deviation range of being approximately equal, for example, the width difference between the two can be less than or equal to 1 μm.

[0079] S41: Thinning the side of the substrate 100 away from the ridge waveguide 210, and depositing a second metal material on the side of the substrate away from the ridge waveguide 210 to form a second electrode 250. For example, referring to the schematic structural diagram of a semiconductor laser shown in FIG15 , the second electrode 250 is an N-type electrode. Accordingly, the material of the second electrode 250 is Ti or Au, and the thickness of the second electrode 250 is 30-500 nm.

[0080] S50: A highly reflective dielectric film layer 261 is formed covering the first surface of the substrate 100. The first surface extends perpendicular to the first direction of the substrate 100. Exemplarily, the reflectivity of the highly reflective dielectric film layer 261 ranges from 95% to 99.99%. By providing the highly reflective dielectric film layer 261 in the semiconductor laser, the output power and performance of the semiconductor laser can be effectively enhanced, thereby improving light utilization efficiency.

[0081] S51: An anti-reflection dielectric film layer 262 is formed covering the second surface of the substrate. The second surface of the substrate 100 is disposed opposite the first surface of the substrate 100, and the second surface extends perpendicular to the first direction of the substrate 100. The anti-reflection dielectric film layer 262 is provided in a semiconductor laser to modify the refraction and interference of light to reduce reflection, thereby improving transmittance and semiconductor laser performance. Exemplarily, the reflectivity of the anti-reflection dielectric film layer 262 ranges from 0.01% to 0.5%.

[0082] The following describes various parts of the semiconductor laser by taking an InGaAsP / InP surface inverse gain coupled DFB-DML semiconductor laser with a wavelength of 1577 nm as an example.

[0083] The semiconductor laser includes a substrate 100 . Specifically, the substrate 100 includes a substrate 101 , a first waveguide limiting layer 102 , an active layer 103 and a second waveguide limiting layer 104 .

[0084] The substrate 101 may be a single-layer structure. For example, the substrate 101 is a heavily doped n-type InP substrate 101. Alternatively, the substrate 101 may be a multi-layer structure. For example, a buffer layer is formed on the heavily doped n-type InP substrate 101. The buffer layer may be an n-type InP buffer layer with a thickness of 500 nm and a doping concentration of 1.5×10 18 cm -3 .

[0085] The first waveguide limiting layer 102 may be a multi-layer structure. For example, the first waveguide limiting layer 102 may be a three-layer structure, i.e., the first waveguide limiting layer 102 may be composed of, from bottom to top, a first sub-waveguide limiting layer, a second sub-waveguide limiting layer, and a third sub-waveguide limiting layer. The thickness of the first sub-waveguide limiting layer may be 10 nm, the fluorescence wavelength may be 968 nm to 841 nm, and the doping concentration of indium gallium arsenide phosphide (InGaAsP) may be 1.5×10 18 cm -3 The thickness of the second sub-waveguide confinement layer can be 40 nm, the fluorescence wavelength is 841 nm, and the doping concentration of indium gallium arsenide (InGaAs) is 1.5×10 18 cm -3 The thickness of the third sub-waveguide confinement layer can be 50 nm, the fluorescence wavelength is 841 nm-1200 nm, and the doping concentration of InGaAsP is 0.5×10 18 cm -3 It is understood that, in other optional examples, the first waveguide limiting layer 102 may also be a single-layer structure. When the number of layers of the first waveguide limiting layer 102 changes, the component ratio of each sub-waveguide limiting layer in the first waveguide limiting layer 102 should also change accordingly.

[0086] The active layer 103 can be composed of quantum wells and barriers, preferably compressively strained quantum wells and tensile strained barriers, with the quantum well materials being indium gallium arsenide phosphide multiple quantum wells, aluminum gallium indium arsenide multiple quantum wells, or aluminum gallium arsenide multiple quantum wells. Exemplarily, the active layer 103 includes six well layers and seven barrier layers, wherein the wells are 6 nm wide, undoped, ~1.3% compressive strain, and have a fluorescence wavelength of 1803 nm; the barrier layers are 6 nm wide, undoped, ~0.5% tensile strain, and have a fluorescence wavelength of 1299 nm.

[0087] The second waveguide limiting layer 104 may be a multi-layer structure. For example, the second waveguide limiting layer 104 may be a four-layer structure, i.e., the second waveguide limiting layer 104 may be composed of, from bottom to top, a fourth sub-waveguide limiting layer, a fifth sub-waveguide limiting layer, a sixth sub-waveguide limiting layer, and a seventh sub-waveguide limiting layer. The thickness of the fourth sub-waveguide limiting layer may be 50 nm, the fluorescence wavelength may be 841-1200 nm, and the doping concentration of InGaAsP may be 0.3×10 18 cm -3 The thickness of the fifth sub-waveguide confinement layer can be 30 nm, the fluorescence wavelength is 841 nm-968 nm, and the doping concentration of InGaAs is 0.5×10 18 cm -3 The thickness of the limiting stop layer of the sixth sub-waveguide 211 can be 10 nm, the fluorescence wavelength is 841 nm-968 nm, and the doping concentration of InGaAsP is 0.5×10 18 cm -3 ); The fluorescence wavelength of the seventh sub-waveguide confinement layer is 1100 nm, and the doping concentration of p-type InGaAsP is 0.5×10 18 cm -3 It is understood that, in other optional examples, the second waveguide limiting layer 104 may also be a single-layer structure. When the number of layers of the second waveguide limiting layer 104 changes, the component ratio of each sub-waveguide limiting layer in the second waveguide limiting layer 104 should also change accordingly.

[0088] The semiconductor laser further comprises a ridge waveguide 210 and a grating 220 stacked on a substrate 100. Specifically:

[0089] The ridge waveguide 210 includes a plurality of sub-waveguides 211 arranged along a first direction of the substrate 100, and adjacent sub-waveguides 211 are separated by an insulating dielectric material. The thickness of each sub-waveguide 211 in the ridge waveguide 210 can be 1750 nm, and the gradient doping concentration in each sub-waveguide 211 is 0.5×10 18 cm -3 -2×10 18 cm -3 .

[0090] The grating 220 includes a first region 221 and a second region 222. The first region 221 of the grating 220 is a multi-layer structure. For example, the first region 221 of the grating 220 is a three-layer structure, that is, the first region 221 of the grating 220 is composed of: a patterned first sub-ohmic contact layer, a patterned second sub-ohmic contact layer, and a patterned third sub-ohmic contact layer from bottom to top. The thickness of the patterned first sub-ohmic contact layer can be 25 nm, the fluorescence wavelength is 1250 nm, and the doping concentration of the heavily doped p-type InGaAsP is 3×10 18 cm -3The thickness of the patterned second sub-ohmic contact layer can be 25 nm, the fluorescence wavelength is 1500 nm, and the doping concentration of the heavily doped p-type InGaAsP is 3×10 18 cm -3 The thickness of the patterned third sub-ohmic contact layer can be 150 nm, the fluorescence wavelength is 1654 nm, and the doping concentration of the heavily doped p-type InGaAs layer is 3×10 19 cm -3 .

[0091] The second region 222 of the grating 220 is provided with an insulating dielectric material. This insulating dielectric material is integrally formed with the insulating dielectric material between the sub-waveguide 211. The first region 221 and the second region 222 of the grating 220 are periodically arranged along a first direction of the substrate 100. The refractive index of the insulating dielectric material in the second region 222 is greater than the refractive index of the semiconductor material in the first region 221. Therefore, when the semiconductor laser is in operation, the operating current can be injected from the first region 221 of the grating 220 instead of from the second region 222. This forms a surface inversion gain coupling grating on top of the waveguide. The inversion gain coupling grating adjusts the phase distribution of light by introducing a phase shift, correcting wavefront distortion of light, such as that caused by the chirp effect, thereby reducing the chirp problem of the semiconductor laser. The refractive index of the insulating dielectric material filled in the second region can be adjusted according to actual needs, increasing the process tolerance of the semiconductor laser manufacturing and thereby improving the yield of the semiconductor laser. In addition, the inversion gain coupling grating only requires a single epitaxial growth process during its formation, effectively reducing the cost of the semiconductor laser.

[0092] It should be noted that the number of ridge waveguides 210 can be adjusted according to actual applications and is not limited to one ridge waveguide 210. In some other optional embodiments, an array of ridge waveguides 210 is formed on the substrate, and a grating 220 is formed on each ridge waveguide 210.

[0093] In some optional embodiments, the semiconductor laser further includes an insulating layer 230 disposed on the substrate 100. Exemplarily, the insulating layer 230 is made of a photosensitive BCB material. The upper surface of the insulating layer 230 is flush with the top of the grating 220, i.e., the thickness of the insulating layer 230 is equal to the total thickness of the ridge waveguide 210 and the grating 220.

[0094] It should be noted that when there are multiple ridge waveguides 210 on the substrate 100, a gap is provided in the insulating layer 230 between adjacent ridge waveguides 210. Exemplarily, the width of the gap is 50 μm, and the length of the gap is generally in the range of 100-1000 μm. The gap serves as a cutting path for dissociating the semiconductor laser, dissociating the substrate into multiple semiconductor lasers including a single ridge waveguide 210.

[0095] It can be understood that the thickness of the insulating layer 230 is equal to the total thickness of the ridge waveguide 210 and the grating 220, which can be equal to absolutely equal and approximately equal, wherein the acceptable deviation range of approximately equal is, for example, the height difference between the two can be less than or equal to 100 nm, and the spacing between the ridge waveguide 210 and the insulating layer 230 can be less than or equal to 1 μm.

[0096] In some optional embodiments, the semiconductor laser further includes a first electrode 240 disposed on the grating 220. Exemplarily, the first electrode 240 is a P-type electrode, the first metal material is Ti, Pt, Au, or other metal materials, and the thickness of the first electrode 240 is 20-400 nm. The first electrode 240 consists of a thin strip on top of the ridge waveguide (width ≤ ridge waveguide width + 1 μm), an electrode pad (a circle with a diameter of 100 μm, with a spacing of ≤ 20 μm from the ridge waveguide), and a connecting portion (width 20 μm) between the two.

[0097] In some optional embodiments, the semiconductor laser further includes a second electrode 250 disposed on a side of the substrate away from the ridge waveguide 210. Exemplarily, the second electrode 250 is an N-type electrode, and accordingly, the material of the second electrode 250 is Ti or Au, and the thickness of the second electrode 250 is 30-500 nm.

[0098] In some optional embodiments, the semiconductor laser further includes a high-reflectivity dielectric film layer 261 disposed on the first surface of the substrate, wherein the extension direction of the first surface is perpendicular to the first direction of the substrate; illustratively, the reflectivity of the high-reflectivity dielectric film layer 261 ranges from 95% to 99.99%.

[0099] In some optional embodiments, the semiconductor laser further includes an anti-reflection dielectric film layer 262 disposed on the second surface of the substrate 100. The second surface of the substrate 100 is disposed opposite to the first surface of the substrate 100, and the second surface extends in a direction perpendicular to the first direction of the substrate 100. Exemplarily, the reflectivity of the anti-reflection dielectric film layer 262 ranges from 0.01% to 0.5%.

[0100] The following describes various parts of the semiconductor laser by taking an AlGaInAs / InP surface inverse gain coupled DFB-DML semiconductor laser with a wavelength of 1550 nm as an example.

[0101] The semiconductor laser includes a substrate 100 . Specifically, the substrate 100 includes a substrate 101 , a first waveguide limiting layer 102 , an active layer 103 and a second waveguide limiting layer 104 .

[0102] The substrate 101 may be a single-layer structure. For example, the substrate 101 is a heavily doped n-type InP substrate 101. Alternatively, the substrate 101 may be a multi-layer structure. For example, a buffer layer is formed on the heavily doped n-type InP substrate 101. The buffer layer may be an n-type InP buffer layer with a thickness of 1500 nm and a doping concentration of 0.5×10 18 cm -3 .

[0103] The first waveguide limiting layer 102 can have a single-layer structure. For example, the first waveguide limiting layer 102 can be formed of AlGaInAs material. The first waveguide limiting layer 102 can have a thickness of 125 nm, a fluorescence wavelength of 900 nm-1000 nm, and be undoped. It is understood that in other optional examples, the first waveguide limiting layer 102 can also have a multi-layer structure. When the number of layers in the first waveguide limiting layer 102 changes, the component ratios of each sub-waveguide limiting layer in the first waveguide limiting layer 102 should also change accordingly.

[0104] The active layer 103 can be composed of quantum wells and barriers, preferably compressively strained quantum wells and tensile strained barriers, with the quantum well materials being indium gallium arsenide phosphide multiple quantum wells, aluminum gallium indium arsenide multiple quantum wells, or aluminum gallium arsenide multiple quantum wells. Exemplarily, the active layer 103 includes three well layers and four barrier layers, wherein the well width is 5.5 nm, undoped, with -1.3% compressive strain, and a fluorescence wavelength of 1850 nm; the barrier width is 10 nm, undoped, with ~0.5% tensile strain, and a fluorescence wavelength of 1100 nm.

[0105] The second waveguide limiting layer 104 can have a single-layer structure. For example, the second waveguide limiting layer can be formed of AlGaInAs material. The second waveguide limiting layer 104 can have a thickness of 110 nm, a fluorescence wavelength of 900 nm-1000 nm, and be undoped. It is understood that in other optional examples, the second waveguide limiting layer 104 can also have a multi-layer structure. When the number of layers in the second waveguide limiting layer 104 changes, the component ratios of the sub-waveguide limiting layers in the second waveguide limiting layer 104 should also change accordingly.

[0106] The semiconductor laser further comprises a ridge waveguide 210 and a grating 220 stacked on a substrate 100. Specifically:

[0107] The ridge waveguide 210 includes a plurality of sub-waveguides 211 arranged along a first direction of the substrate 100, and adjacent sub-waveguides 211 are separated by an insulating dielectric material. The thickness of each sub-waveguide 211 in the ridge waveguide 210 can be 1900 nm, and the doping concentration in each sub-waveguide 211 is gradually changed from 0.5×10 18 cm -3 –2.5×10 18cm -3 .

[0108] The grating 220 includes a first region 221 and a second region 222. The first region 221 of the grating 220 is a multi-layer structure. For example, the first region 221 of the grating 220 is a three-layer structure, that is, the first region 221 of the grating 220 is composed of: a patterned first sub-ohmic contact layer, a patterned second sub-ohmic contact layer, and a patterned third sub-ohmic contact layer from bottom to top. The thickness of the patterned first sub-ohmic contact layer can be 25 nm, the fluorescence wavelength is 1100 nm, and the doping concentration of the heavily doped p-type InGaAsP is 3×10 18 cm -3 The thickness of the patterned second sub-ohmic contact layer can be 50 nm, the fluorescence wavelength is 1300 nm, and the doping concentration of the heavily doped p-type InGaAsP is 5×10 18 cm -3 The thickness of the patterned third sub-ohmic contact layer can be 150 nm, the fluorescence wavelength is 1654 nm, and the doping concentration of the heavily doped p-type InGaAs layer is 2.5×10 19 cm -3 .

[0109] The second region 222 of the grating 220 is provided with an insulating dielectric material. This insulating dielectric material is integrally formed with the insulating dielectric material between the sub-waveguide 211. The first region 221 and the second region 222 of the grating 220 are periodically arranged along a first direction of the substrate 100. The refractive index of the insulating dielectric material in the second region 222 is greater than the refractive index of the semiconductor material in the first region 221. Therefore, when the semiconductor laser is in operation, the operating current can be injected from the first region 221 of the grating 220 instead of from the second region 222, thereby forming a surface inversion gain coupling grating on the top of the waveguide. The inversion gain coupling grating adjusts the phase distribution of light by introducing a phase shift, correcting wavefront distortion of light, such as wavefront distortion caused by the chirp effect, thereby reducing the chirp problem of the semiconductor laser. The refractive index of the insulating dielectric material filled in the second region can be adjusted according to actual needs, increasing the process tolerance of the semiconductor laser manufacturing and thus improving the yield of the semiconductor laser. In addition, the inversion gain coupling grating only requires a single epitaxial growth during the formation process, effectively reducing the cost of the semiconductor laser.

[0110] It should be noted that the number of ridge waveguides 210 can be adjusted according to actual applications and is not limited to one ridge waveguide 210. In some other optional embodiments, an array of ridge waveguides 210 is formed on the substrate, and a grating 220 is formed on each ridge waveguide 210.

[0111] In some optional embodiments, the semiconductor laser further includes an insulating layer 230 disposed on the substrate 100. Exemplarily, the insulating layer 230 is made of a photosensitive BCB material. The upper surface of the insulating layer 230 is flush with the top of the grating 220, i.e., the thickness of the insulating layer 230 is equal to the total thickness of the ridge waveguide 210 and the grating 220.

[0112] It should be noted that when there are multiple ridge waveguides 210 on the substrate 100, a gap is provided in the insulating layer 230 between adjacent ridge waveguides 210. Exemplarily, the width of the gap is 50 μm, and the length of the gap is generally in the range of 100-1000 μm. The gap serves as a cutting path for dissociating the semiconductor laser, dissociating the substrate into multiple semiconductor lasers including a single ridge waveguide 210.

[0113] It can be understood that the thickness of the insulating layer 230 is equal to the total thickness of the ridge waveguide 210 and the grating 220, which can be equal to absolutely equal and approximately equal, wherein the acceptable deviation range of approximately equal is, for example, the height difference between the two can be less than or equal to 100 nm, and the spacing between the ridge waveguide 210 and the insulating layer 230 can be less than or equal to 1 μm.

[0114] In some optional embodiments, the semiconductor laser further includes a first electrode 240 disposed on the grating 220. Exemplarily, the first electrode 240 is a P-type electrode, the first metal material is Ti, Pt, Au, or other metal materials, and the thickness of the first electrode 240 is 20-400 nm. The first electrode 240 consists of a thin strip on top of the ridge waveguide (width ≤ ridge waveguide width + 1 μm), an electrode pad (a circle with a diameter of 100 μm, with a spacing of ≤ 20 μm from the ridge waveguide), and a connecting portion (width 20 μm) between the two.

[0115] In some optional embodiments, the semiconductor laser further includes a second electrode 250 disposed on a side of the substrate away from the ridge waveguide 210. Exemplarily, the second electrode 250 is an N-type electrode, and accordingly, the material of the second electrode 250 is Ti or Au, and the thickness of the second electrode 250 is 30-500 nm.

[0116] In some optional embodiments, the semiconductor laser further includes a high-reflectivity dielectric film layer 261 disposed on the first surface of the substrate, wherein the extension direction of the first surface is perpendicular to the first direction of the substrate; illustratively, the reflectivity of the high-reflectivity dielectric film layer 261 ranges from 95% to 99.99%.

[0117] In some optional embodiments, the semiconductor laser further includes an anti-reflection dielectric film layer 262 disposed on the second surface of the substrate 100. The second surface of the substrate 100 is disposed opposite to the first surface of the substrate 100, and the second surface extends in a direction perpendicular to the first direction of the substrate 100. Exemplarily, the reflectivity of the anti-reflection dielectric film layer 262 ranges from 0.01% to 0.5%.

[0118] The following describes various parts of the semiconductor laser by taking an InGaAsP / InP surface inverse gain coupled DFB-DML semiconductor laser with a wavelength of 1550 nm as an example.

[0119] The semiconductor laser includes a substrate 100 . Specifically, the substrate 100 includes a substrate 101 , a first waveguide limiting layer 102 , an active layer 103 and a second waveguide limiting layer 104 .

[0120] The substrate 101 may be a single-layer structure. For example, the substrate 101 is a heavily doped n-type InP substrate 101. Alternatively, the substrate 101 may be a multi-layer structure. For example, a buffer layer is formed on the heavily doped n-type InP substrate 101. The buffer layer may be an n-type InP buffer layer with a thickness of 1500 nm and a doping concentration of 0.5×10 18 cm -3 .

[0121] The first waveguide limiting layer 102 can have a single-layer structure. For example, the first waveguide limiting layer 102 can be formed of InGaAsP material. The first waveguide limiting layer 102 can have a thickness of 125 nm, a fluorescence wavelength of 900 nm-1000 nm, and be undoped. It is understood that in other optional examples, the first waveguide limiting layer 102 can also have a multi-layer structure. When the number of layers in the first waveguide limiting layer 102 changes, the component ratios of each sub-waveguide limiting layer in the first waveguide limiting layer 102 should also change accordingly.

[0122] The active layer 103 can be composed of quantum wells and barriers, preferably compressively strained quantum wells and tensile strained barriers, with the quantum well materials being indium gallium arsenide phosphide multiple quantum wells, aluminum gallium indium arsenide multiple quantum wells, or aluminum gallium arsenide multiple quantum wells. Exemplarily, the active layer 103 includes three well layers and four barrier layers, wherein the well width is 5.5 nm, undoped, with -1.3% compressive strain, and a fluorescence wavelength of 1850 nm; the barrier width is 10 nm, undoped, with ~0.5% tensile strain, and a fluorescence wavelength of 1100 nm.

[0123] The second waveguide limiting layer 104 can have a single-layer structure. For example, the second waveguide limiting layer can be formed of InGaAsP material. The second waveguide limiting layer 104 can have a thickness of 110 nm, a fluorescence wavelength of 900 nm-1000 nm, and be undoped. It is understood that in other optional examples, the second waveguide limiting layer 104 can also have a multi-layer structure. When the number of layers in the second waveguide limiting layer 104 changes, the component ratios of the sub-waveguide limiting layers in the second waveguide limiting layer 104 should also change accordingly.

[0124] The semiconductor laser further comprises a ridge waveguide 210 and a grating 220 stacked on a substrate 100. Specifically:

[0125] The ridge waveguide 210 includes a plurality of sub-waveguides 211 arranged along a first direction of the substrate 100, and adjacent sub-waveguides 211 are separated by an insulating dielectric material. The thickness of each sub-waveguide 211 in the ridge waveguide 210 can be 1900 nm, and the doping concentration in each sub-waveguide 211 is gradually changed from 0.5×10 18 cm -3 –2.5×10 18 cm -3 .

[0126] The grating 220 includes a first region 221 and a second region 222. The first region 221 of the grating 220 is a multi-layer structure. For example, the first region 221 of the grating 220 is a three-layer structure, that is, the first region 221 of the grating 220 is composed of: a patterned first sub-ohmic contact layer, a patterned second sub-ohmic contact layer, and a patterned third sub-ohmic contact layer from bottom to top. The thickness of the patterned first sub-ohmic contact layer can be 25 nm, the fluorescence wavelength is 1100 nm, and the doping concentration of the heavily doped p-type InGaAsP is 3×10 18 cm -3 The thickness of the patterned second sub-ohmic contact layer can be 50 nm, the fluorescence wavelength is 1300 nm, and the doping concentration of the heavily doped p-type InGaAsP is 5×10 18 cm -3 The thickness of the patterned third sub-ohmic contact layer can be 150 nm, the fluorescence wavelength is 1654 nm, and the doping concentration of the heavily doped p-type InGaAs layer is 2.5×10 19 cm -3 .

[0127] The second region 222 of the grating 220 is provided with an insulating dielectric material. This insulating dielectric material is integrally formed with the insulating dielectric material between the sub-waveguide 211. The first region 221 and the second region 222 of the grating 220 are periodically arranged along a first direction of the substrate 100. The refractive index of the insulating dielectric material in the second region 222 is greater than the refractive index of the semiconductor material in the first region 221. Therefore, when the semiconductor laser is in operation, the operating current can be injected from the first region 221 of the grating 220 instead of from the second region 222, thereby forming a surface inversion gain coupling grating on the top of the waveguide. The inversion gain coupling grating adjusts the phase distribution of light by introducing a phase shift, correcting wavefront distortion of light, such as wavefront distortion caused by the chirp effect, thereby reducing the chirp problem of the semiconductor laser. The refractive index of the insulating dielectric material filled in the second region can be adjusted according to actual needs, increasing the process tolerance of the semiconductor laser manufacturing and thus improving the yield of the semiconductor laser. In addition, the inversion gain coupling grating only requires a single epitaxial growth during the formation process, effectively reducing the cost of the semiconductor laser.

[0128] It should be noted that the number of ridge waveguides 210 can be adjusted according to actual applications and is not limited to one ridge waveguide 210. In some other optional embodiments, an array of ridge waveguides 210 is formed on the substrate, and a grating 220 is formed on each ridge waveguide 210.

[0129] In some optional embodiments, the semiconductor laser further includes an insulating layer 230 disposed on the substrate 100. Exemplarily, the insulating layer 230 is made of a photosensitive BCB material. The upper surface of the insulating layer 230 is flush with the top of the grating 220, i.e., the thickness of the insulating layer 230 is equal to the total thickness of the ridge waveguide 210 and the grating 220.

[0130] It should be noted that when there are multiple ridge waveguides 210 on the substrate 100, a gap is provided in the insulating layer 230 between adjacent ridge waveguides 210. Exemplarily, the width of the gap is 50 μm, and the length of the gap is generally in the range of 100-1000 μm. The gap serves as a cutting path for dissociating the semiconductor laser, dissociating the substrate into multiple semiconductor lasers including a single ridge waveguide 210.

[0131] It can be understood that the thickness of the insulating layer 230 is equal to the total thickness of the ridge waveguide 210 and the grating 220, which can be equal to absolutely equal and approximately equal, wherein the acceptable deviation range of approximately equal is, for example, the height difference between the two can be less than or equal to 100 nm, and the spacing between the ridge waveguide 210 and the insulating layer 230 can be less than or equal to 1 μm.

[0132] In some optional embodiments, the semiconductor laser further includes a first electrode 240 disposed on the grating 220. Exemplarily, the first electrode 240 is a P-type electrode, the first metal material is Ti, Pt, Au, or other metal materials, and the thickness of the first electrode 240 is 20-400 nm. The first electrode 240 consists of a thin strip on top of the ridge waveguide (width ≤ ridge waveguide width + 1 μm), an electrode pad (a circle with a diameter of 100 μm, with a spacing of ≤ 20 μm from the ridge waveguide), and a connecting portion (width 20 μm) between the two.

[0133] In some optional embodiments, the semiconductor laser further includes a second electrode 250 disposed on a side of the substrate away from the ridge waveguide 210. Exemplarily, the second electrode 250 is an N-type electrode, and accordingly, the material of the second electrode 250 is Ti or Au, and the thickness of the second electrode 250 is 30-500 nm.

[0134] In some optional embodiments, as shown in FIG16 , the semiconductor laser further includes a high-reflectivity dielectric film layer 261 disposed on the first surface of the substrate, wherein the extension direction of the first surface is perpendicular to the first direction of the substrate; illustratively, the reflectivity of the high-reflectivity dielectric film layer 261 ranges from 95% to 99.99%.

[0135] In some optional embodiments, as shown in FIG16 , the semiconductor laser further includes an anti-reflection dielectric film layer 262 disposed on the second surface of the substrate 100. The second surface of the substrate 100 is disposed opposite to the first surface of the substrate 100, and the second surface extends perpendicular to the first direction of the substrate 100. Exemplarily, the reflectivity of the anti-reflection dielectric film layer 262 ranges from 0.01% to 0.5%.

[0136] It will be understood that the above examples are merely examples listed for a better understanding of the technical solutions of the embodiments of the present application, and are not intended to be the sole limitation on the embodiments of the present application. The materials for forming the first waveguide limiting layer, the active layer, and the second waveguide limiting layer of the semiconductor laser can be selected according to actual conditions to adjust the emission wavelength of the semiconductor laser. The materials for the first waveguide limiting layer, the active layer, and the second waveguide limiting layer can be group III-IV compounds.

[0137] Another embodiment of the present application also provides a non-transitory computer-readable storage medium for use with a computer, wherein the computer has software for creating and manufacturing the above-mentioned semiconductor laser, and the computer-readable storage medium has one or more computer-readable data structures stored thereon, and the one or more computer-readable data structures have control data for manufacturing the semiconductor laser provided in any one of the diagrams provided above, such as photoresist layer data.

[0138] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A semiconductor laser, characterized in that: include: substrate; A ridge waveguide, wherein the ridge waveguide is disposed on the substrate and extends along a first direction of the substrate; A grating is arranged on the top of the ridge waveguide, wherein the grating includes a first region and a second region periodically arranged along the first direction, the first region includes a semiconductor material, the second region includes an insulating dielectric material, and the refractive index of the insulating dielectric material is greater than the refractive index of the semiconductor material.

2. The semiconductor laser according to claim 1, characterized in that The ridge waveguide includes a plurality of sub-waveguides arranged along the first direction, and the plurality of sub-waveguides are separated by insulating dielectric materials.

3. The semiconductor laser according to claim 2, characterized in that The sub-waveguides correspond to the first regions of the grating one by one, and the insulating dielectric material between the sub-waveguides is integrally formed with the second region of the grating.

4. The semiconductor laser according to any one of claims 1 to 3, characterized in that: The base includes a substrate and an active layer disposed on the substrate.

5. The semiconductor laser according to claim 4, characterized in that The average refractive index of the active layer is greater than the refractive index of the insulating medium material.

6. The semiconductor laser according to claim 4 or 5, characterized in that: A first waveguide limiting layer is also arranged between the substrate and the active layer.

7. The semiconductor laser according to any one of claims 4 to 6, characterized in that: A second waveguide limiting layer is arranged on the active layer.

8. The semiconductor laser according to any one of claims 1 to 7, characterized in that: The semiconductor laser further includes a first electrode, which is disposed on the grating, and a projection of the grating on the substrate at least covers a portion of a projection of the first electrode on the substrate.

9. The semiconductor laser according to any one of claims 1 to 8, characterized in that: The semiconductor laser further includes a second electrode, which is disposed on a side of the substrate away from the ridge waveguide.

10. The semiconductor laser according to any one of claims 1 to 9, characterized in that: The substrate comprises a first surface and a second surface opposite to the first surface, and an extension direction of the first surface and an extension direction of the second surface are both perpendicular to the first direction of the substrate; The semiconductor laser further comprises: A high reflective dielectric film layer covers the first surface of the substrate.

11. The semiconductor laser according to claim 10, characterized in that The semiconductor laser further comprises: An anti-reflection dielectric film layer covers the second surface of the substrate.

12. A method for manufacturing a semiconductor laser, characterized in that: include: forming a base; A stacked ridge waveguide and a grating are formed on the substrate, wherein the ridge waveguide extends along a first direction of the substrate; the grating includes a first region and a second region periodically arranged along the first direction, the first region includes a semiconductor material, and the second region includes an insulating dielectric material, and the refractive index of the insulating dielectric material is greater than the refractive index of the semiconductor material.

13. The method according to claim 12, characterized in that Forming a stacked ridge waveguide and a grating on the substrate comprises: forming a waveguide layer on the substrate; forming an ohmic contact layer on the waveguide layer; Periodically etching the waveguide layer and the ohmic contact layer to form periodically arranged openings on the waveguide layer and the ohmic contact layer, wherein the openings penetrate the waveguide layer and the ohmic contact layer; An insulating dielectric material is deposited in the opening to form the stacked ridge waveguide and the grating, wherein the ridge waveguide includes a plurality of sub-waveguides, and the plurality of sub-waveguides are separated by insulating dielectric material.

14. The method according to claim 12 or 13, characterized in that Forming the substrate includes: forming a substrate; An active layer is formed on the substrate.

15. The method according to claim 14, characterized in that Before forming the active layer, forming the substrate further comprises: A first waveguide confinement layer is formed on the substrate.

16. The method according to claim 14 or 15, characterized in that Forming the substrate also includes: A second waveguide confinement layer is formed on the active layer.

17. The method according to any one of claims 12 to 16, characterized in that: The production method further comprises: A first metal material is deposited on the grating to form a first electrode, and a projection of the grating on the substrate covers a projection of the first electrode on the substrate.

18. The method according to any one of claims 12 to 17, characterized in that: The production method further comprises: thinning the substrate; A second metal material is deposited on a side of the substrate away from the ridge waveguide to form a second electrode.

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