Semiconductor laser device and method for manufacturing semiconductor laser device

Abstract

The embodiment of the present application relates to the technical field of laser device, and discloses a semiconductor laser device and a manufacturing method of the semiconductor laser device, the semiconductor laser device comprises: an active module, a passive waveguide and a ridge waveguide, the active module comprises a quantum well active layer, the quantum well active layer is used for emitting laser, the passive waveguide surrounds the outside of the active module in the circumferential direction, the ridge waveguide is connected with the top surface of the active module and the passive waveguide, the ridge waveguide extends along the emission direction of laser, the ridge waveguide comprises a first conducting part and a second conducting part connected with each other, the ridge width of the second conducting part near one end of the first conducting part gradually increases along the emission direction of laser, and is greater than the ridge width of the first conducting part, and the second conducting part is located on the light-emitting side of the active module, so that the anti-reflection capability of the semiconductor laser device is improved.

Description

Technical Field

[0001] This application relates to the field of laser device technology, and more particularly to a semiconductor laser device and a method for manufacturing a semiconductor laser device. Background Technology

[0002] Semiconductor laser devices, such as lasers, experience some reflection when the emitted laser light passes through lenses, fiber optic connectors, and other components, which can affect the semiconductor laser device. In related technologies, isolators are typically placed between the semiconductor laser device and the optical fiber to reduce the impact of reflected light on the semiconductor laser device. Isolators account for a significant portion of the overall cost of optical modules, increasing the overall cost. Summary of the Invention

[0003] This application aims to address at least one of the technical problems existing in the prior art or related technologies.

[0004] Therefore, a first aspect of the present invention provides a semiconductor laser device.

[0005] A second aspect of the present invention provides a method for manufacturing a semiconductor laser device.

[0006] In view of the above, a semiconductor laser device is proposed according to the first aspect of the technical solution of this application. The semiconductor laser device includes an active module, a passive waveguide, and a ridge waveguide. The active module includes a quantum well active layer for emitting laser light. The passive waveguide surrounds the outside of the active module circumferentially. The ridge waveguide is connected to the top surface of the active module and the passive waveguide. The ridge waveguide extends along the laser emission direction and includes a first conductive part and a second conductive part connected to each other. The ridge width of the second conductive part near the end of the first conductive part gradually increases along the laser emission direction and is greater than the ridge width of the first conductive part. The second conductive part is located on the light-emitting side of the active module and is opposite to the passive waveguide.

[0007] Optionally, in some of the technical solutions provided in this application, the active module may further include: an upper waveguide layer, a lower waveguide layer, a grating layer, and a current-limiting layer. The upper waveguide layer is connected to the top surface of the quantum well active layer, the lower waveguide layer is connected to the bottom surface of the quantum well active layer, the grating layer is connected to the bottom surface of the lower waveguide layer, and the current-limiting layer is connected to the top surface of the upper waveguide layer and the ridge waveguide, respectively.

[0008] Optionally, in some technical solutions provided in this application, the semiconductor laser device further includes: an etch stop layer and a second filling layer, wherein the etch stop layer is connected to the top surface of the active module and the passive waveguide, and the second filling layer is connected to the top surface of the etch stop layer. The ridge waveguide includes: a first filling layer, which is connected to the top surface of the etch stop layer; the second filling layer is made of the same material as the first filling layer and is located on both sides of the first filling layer; the second filling layers on both sides form processing grooves with the first filling layer respectively; and the first filling layer constitutes a first conductive portion and a second conductive portion.

[0009] Optionally, in some technical solutions provided in this application, the ridge waveguide further includes: a first contact layer, which is connected to the top surface of the first filling layer. The two ends of the first contact layer along the laser emission direction respectively contract inward to form insulating spaces, with the insulating spaces on both sides facing the passive waveguide. The semiconductor laser device further includes: a second contact layer, an insulating layer, and a metal layer. The second contact layer is connected to the top surface of the second filling layer, and the material of the second contact layer is the same as that of the first contact layer. The insulating layer is connected to the outer end face of the ridge waveguide, and a contact window is provided on the insulating layer, which avoids the first contact layer. The metal layer covers the ridge waveguide and the insulating layer, and the metal layer forms an ohmic contact with the first contact layer.

[0010] Optionally, in some technical solutions provided in this application, the semiconductor laser device further includes: a buffer layer and a substrate layer, the buffer layer being connected to the bottom surface of the active module, the substrate layer being connected to the bottom surface of the buffer layer, the buffer layer and the substrate layer being made of the same material, the etching stop layer and the buffer layer extending circumferentially out of the active module and forming a receiving space, and the passive waveguide being located within the receiving space.

[0011] The second aspect of this application provides a method for manufacturing a semiconductor laser device. This method is used to manufacture the semiconductor laser device provided in any of the first aspects of the above-mentioned technical solutions. The method includes: epitaxially growing a buffer layer on the top surface of a substrate layer; growing an active module on the top surface of the buffer layer; removing part of the outer end of the active module along the circumferential direction to form a receiving space; growing a passive waveguide in the receiving space; and manufacturing a ridge waveguide on the top surface of the passive waveguide and the active module.

[0012] In some of the technical solutions provided in this application, optionally, the step of growing an active module on the top surface of the buffer layer specifically includes: growing a grating layer on the top surface of the buffer layer; growing a lower waveguide layer on the top surface of the grating layer; growing a quantum well active layer on the top surface of the lower waveguide layer; growing an upper waveguide layer on the top surface of the quantum well active layer; and growing a current-limiting layer on the top surface of the upper waveguide layer.

[0013] In some technical solutions provided in this application, optionally, the step of fabricating a ridge waveguide on the top surface of the passive waveguide and the active module specifically includes: growing an etch stop layer on the top surface of the passive waveguide and the active module; growing a fill layer on the top surface of the etch stop layer; growing a contact layer on the top surface of the fill layer; processing two processing grooves on the fill layer and the contact layer to form a first fill layer and a second fill layer, as well as a first contact layer prototype and a second contact layer; removing the first contact layer prototype above the passive waveguide to process an insulating space, forming the first contact layer.

[0014] Optionally, after the step of processing the insulating space, some technical solutions provided in this application may further include: growing an insulating layer on the outside of the ridge waveguide; removing the insulating layer above the first contact layer to process a contact window; depositing a covering metal layer on top of the first contact layer and the insulating layer; and cutting the metal layer.

[0015] In some technical solutions provided in this application, optionally, before the step of removing the insulating layer above the first contact layer, the method further includes: removing an insulating layer of a predetermined width at both ends of the insulating layer along a direction perpendicular to laser emission. And / or after the step of cutting the metal layer, the method further includes: grinding and polishing the substrate layer to process the thickness of the semiconductor laser device to a predetermined thickness; and depositing metal on the bottom surface of the substrate layer.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: By setting up a horn-shaped ridge waveguide and a passive waveguide that work together, the reflected light, after being reflected to the end face of the semiconductor laser device, must pass through a section composed of the passive waveguide and the horn-shaped ridge waveguide before entering the quantum well active layer. Within this section, the reflected light contracts due to the narrowing of the ridge waveguide, which significantly reduces the mode coupling efficiency of the light wave and lowers the reverse transmittance. This reduces the amount of reflected light entering the quantum well active layer, improves the stability of the optical field within the resonant cavity, enhances the anti-reflection capability of the semiconductor laser device, meets the anti-reflection requirements of the semiconductor laser device, eliminates the need for isolators, and greatly reduces the overall manufacturing cost of the optical module. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 One of the schematic diagrams of a semiconductor laser device according to an embodiment of this application; Figure 2A second schematic diagram of the structure of a semiconductor laser device according to an embodiment of this application; Figure 3 A third schematic diagram of the structure of a semiconductor laser device according to an embodiment of this application; Figure 4 This is a schematic flowchart illustrating a method for manufacturing a semiconductor laser device according to an embodiment of this application.

[0018] in, Figures 1 to 4 The correspondence between the reference numerals and component names in the attached drawings is as follows: 10 Semiconductor laser device, 100 Active module, 110 Current limiting layer, 120 Upper waveguide layer, 130 Quantum well active layer, 140 Lower waveguide layer, 150 Grating layer, 200 Passive waveguide, 300 Ridge waveguide, 310 First conductive part, 320 Second conductive part, 330 First filling layer, 340 First contact layer, 410 Etching stop layer, 420 Second filling layer, 430 Second contact layer, 440 Insulating space, 450 Processing groove, 500 Insulating layer, 600 Buffer layer, 700 Substrate layer, 800 Accommodation space, 900 Metal layer. Detailed Implementation

[0019] To better understand the above technical solutions, the technical solutions of the embodiments of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0020] The first aspect of this application provides a semiconductor laser device 10, such as... Figure 1 and Figure 2 As shown, the semiconductor laser device 10 includes an active module 100, a passive waveguide 200, and a ridge waveguide 300. The active module 100 includes a quantum well active layer 130 for emitting laser light. The passive waveguide 200 surrounds the outer side of the active module 100 circumferentially. The ridge waveguide 300 is connected to the top surface of the active module 100 and the passive waveguide 200. The ridge waveguide 300 extends along the laser emission direction and includes a first conductive portion 310 and a second conductive portion 320 connected to each other. The ridge width of the second conductive portion 320 near the end of the first conductive portion 310 gradually increases along the laser emission direction and is greater than the ridge width of the first conductive portion 310. The second conductive portion 320 is located on the light-emitting side of the active module 100 and is opposite to the passive waveguide 200.

[0021] In this embodiment, electrons in the quantum well active layer 130 are in an unstable high-energy state. The electrons rapidly transition to a low-energy state and release photons, generating an initial light field. The photon conduction band electrons absorb and transition, emitting two photons, forming stimulated emission. The high-energy level with a higher conduction band electron state density continuously generates stimulated emission, enhancing the light field and enabling the quantum well active layer 130 to emit laser light to the outside.

[0022] The active quantum well layer 130 can be InAlGaAs MQWs (Multi-Quantum Wells). The active quantum well layer 130 of the active module 100 is the location for generating photons and gain. It consists of multiple barriers and wells (with varying bandgap widths) forming a strained quantum well structure, which can effectively increase the optical confinement factor, thereby increasing the output power of the semiconductor laser device 10. It can also improve the differential gain of the semiconductor laser device 10 and enhance its modulation characteristics.

[0023] Figure 1 and Figure 2 In the diagram, the arrow at position X points to the laser emission direction, and the arrow at position R points to the circumference of the active module 100. The passive waveguide 200 surrounds the outer periphery of the active module 100, forming part of the outer end of the semiconductor laser device 10. The height of the active module 100 and the height of the passive waveguide 200 are the same. The passive waveguide 200 can be an InGaAsP PWS (passive waveguide). After the chip is naturally cleaved, the end face is a passive waveguide 200, avoiding Auger-Schönlein recombination and material oxidation at the end face, significantly improving the reliability of the conductor laser device. At the same time, the passive waveguide 200 does not constitute the resonant cavity of the conductor laser device, and the width variation of the ridge waveguide 300 will not cause the generation of higher-order modes.

[0024] The ridge waveguide 300 is located at the top of the active module 100 and the passive waveguide 200, and extends along the laser emission direction. The end faces on both sides of the ridge waveguide 300 are flush with the outer end faces on both sides of the passive waveguide 200, and the ridge waveguide 300 bulges upwards. The ridge waveguide 300 includes a first conductive section 310 and a second conductive section 320 connected to each other. Figure 2In the diagram, D represents the ridge width. The second conductive section 320, located near the end of the first conductive section 310, has a ridge width that gradually increases along the laser emission direction and is greater than the ridge width of the first conductive section 310. The ridge width at the other end of the second conductive section 320 remains consistent. The second conductive section 320 is located outside the laser-emitting end face of the active module 100, forming a horn-shaped waveguide structure with an expanded width at one end. The expanded position is located above the passive waveguide 200. The horn-shaped opening end of the ridge waveguide 300 faces the laser-emitting end face and cooperates with the passive waveguide 200. The ridge waveguide 300 achieves lateral control of photons and charge carriers through a lower equivalent refractive index, limiting the transmission of the generated laser and causing the laser to exit from the end face.

[0025] For example, the length of the ridge waveguide 300 is 20µm to 40µm, the ridge width of the first conductive part 310 is 2µm, the ridge width of the light-emitting end of the second conductive part 320 is 4µm to 6µm, the sidewall of the connection end of the second conductive part 320 is a slope, and the expansion angle between the slope and the sidewall of the first conductive part 310 is 30° to 50°.

[0026] It should be noted that after the laser emitted by the quantum well active layer 130 is emitted, part of the laser is reflected and returns to the end face of the semiconductor laser device 10, and enters the quantum well active layer 130, affecting the stability of the optical field in the resonant cavity.

[0027] By setting up a horn-shaped ridge waveguide 300 and a passive waveguide 200 that cooperate with each other, the reflected light, after being reflected to the end face of the semiconductor laser device 10, needs to pass through a section composed of the passive waveguide 200 and the horn-shaped ridge waveguide 300 before entering the quantum well active layer 130. Within this section, the reflected light contractes due to the narrowing of the ridge waveguide 300, which significantly reduces the mode coupling efficiency of the light wave and reduces the reverse transmittance. This reduces the amount of reflected light entering the quantum well active layer 130, improves the stability of the optical field in the resonant cavity, enhances the anti-reflection capability of the semiconductor laser device 10, meets the anti-reflection requirements of the semiconductor laser device 10, eliminates the isolator, and greatly reduces the overall manufacturing cost of the optical module.

[0028] In some embodiments provided in this application, such as Figure 1 As shown, the active module 100 may optionally include an upper waveguide layer 120, a lower waveguide layer 140, a grating layer 150, and a current limiting layer 110. The upper waveguide layer 120 is connected to the top surface of the quantum well active layer 130, the lower waveguide layer 140 is connected to the bottom surface of the quantum well active layer 130, the grating layer 150 is connected to the bottom surface of the lower waveguide layer 140, and the current limiting layer 110 is connected to the top surface of the upper waveguide layer 120 and the ridge waveguide 300, respectively.

[0029] In this embodiment, the upper waveguide layer 120 and the lower waveguide layer 140 are located on both sides of the quantum well active layer 130, respectively. The upper waveguide layer 120 and the lower waveguide layer 140 are InAlGaAs GRIN-SCH (Gradient Refractive Index Separate Confinement Heterostructure, where gradient refractive indices confine heterostructures). The upper waveguide layer 120 and the lower waveguide layer 140 have a large bandgap difference with the quantum well active layer 130, confining carriers within the quantum well active layer 130. Furthermore, the upper waveguide layer 120 and the lower waveguide layer 140 have a small refractive index difference with the quantum well active layer 130, and the refractive index gradually decreases from the quantum well active layer 130 outwards, confining photons within the quantum well active layer 130, the upper waveguide layer 120, and the lower waveguide layer 140, thereby increasing the optical field confinement factor. Gradual composition can also effectively improve lattice matching and enhance crystal epitaxial quality, while reducing the number of internal defects and nonradiative recombination centers.

[0030] The grating layer 150 is located below the lower waveguide layer 140. The grating layer 150 comprises InGaAsP and InP, with AlGaInAs interspersed among the InP layers. The grating layer 150 forms a periodically arranged structure, enabling light of a specific wavelength to be effectively reflected back into the cavity, thereby achieving laser oscillation. The grating layer 150 constitutes a resonant cavity, allowing light waves to propagate repeatedly within it and enhancing their intensity. Applying voltage and injecting current to the chip causes electrons in the quantum well active layer 130 to continuously generate stimulated emission. Under the negative feedback of the grating layer 150, the active module 100 operates in a single longitudinal mode. The grating layer 150 acts as a mode selector, filtering out specific laser modes.

[0031] The current-limiting layer 110 is located between the upper waveguide layer 120 and the ridge waveguide 300. The current-limiting layer 110 can be an InAlAs subcladding. The current-limiting layer 110 can restrict the diffusion of charge carriers from the active module 100 in the N region to the ridge waveguide 300 in the P region, so that the charge carriers are concentrated in the quantum well active layer 130, reducing the Ith (Lasing Threshold) and improving the photoelectric conversion efficiency.

[0032] In some embodiments provided in this application, such as Figure 3As shown, optionally, the semiconductor laser device 10 further includes: an etch stop layer 410 and a second filler layer 420. The etch stop layer 410 is connected to the top surface of the active module 100 and the passive waveguide 200, and the second filler layer 420 is connected to the top surface of the etch stop layer 410. The ridge waveguide 300 includes: a first filler layer 330, which is connected to the top surface of the etch stop layer 410. The material of the second filler layer 420 is the same as that of the first filler layer 330, and it is located on both sides of the first filler layer 330. Processing grooves 450 are formed between the second filler layers 420 on both sides and the first filler layer 330, respectively. The first filler layer 330 constitutes the first conductive portion 310 and the second conductive portion 320.

[0033] In this embodiment, the etch stop layer 410 can be InGaAsP, and both the second fill layer 420 and the first fill layer 330 are InP cladding. During the fabrication of the ridge waveguide 300, the etch stop layer 410 and the fill layer are epitaxially grown sequentially on the top surfaces of the passive waveguide 200 and the active module 100. Part of the fill layer is removed on the wafer surface through photolithography, etching, and etching, and two processing trenches 450 are formed, dividing the fill layer into a first fill layer 330 and a second fill layer 420. The first fill layer 330 is located between the two second fill layers 420, and the second fill layers 420 on both sides form processing trenches 450 with the first fill layer 330, respectively. Wet etching is generally used. To control the morphology after etching, the etch stop layer 410 is provided to block the etching solution and prevent it from continuing to etch the active module 100 downwards.

[0034] The first conductive section 310 and the second conductive section 320 are constructed from a first filling layer 330, which forms a horn shape of a waveguide structure.

[0035] For example, the depth of the processing groove 450 is 1.5um to 2um.

[0036] In some embodiments provided in this application, such as Figure 3As shown, optionally, the ridge waveguide 300 further includes: a first contact layer 340, which is connected to the top surface of the first filling layer 330. The two ends of the first contact layer 340 along the laser emission direction respectively contract inward to form insulating spaces 440, with the insulating spaces 440 on both sides respectively opposite to the passive waveguide 200. The semiconductor laser device 10 further includes: a second contact layer 430, an insulating layer 500, and a metal layer 900. The second contact layer 430 is connected to the top surface of the second filling layer 420, and the material of the second contact layer 430 is the same as that of the first contact layer 340. The insulating layer 500 is connected to the outer end face of the ridge waveguide 300, and a contact window is provided on the insulating layer 500, which avoids the first contact layer 340. The metal layer 900 covers the ridge waveguide 300 and the insulating layer 500, and the metal layer 900 forms an ohmic contact with the first contact layer 340.

[0037] In this embodiment, the first contact layer 340 and the second contact layer 430 can be InGaAs. The contact layer is epitaxially grown on the outer side of the filler layer. When part of the filler layer is removed from the wafer surface by photolithography, etching, and etching, part of the contact layer is also removed, and two processing grooves 450 are formed, dividing the contact layer into a first contact layer 340 prototype and a second contact layer 430. The first contact layer 340 prototype is located between the two second contact layers 430. Part of the first contact layer 340 prototype is removed at both ends by photolithography and etching, that is, the first contact layer 340 prototype above the passive waveguide 200 is removed, and an insulating space 440 is formed to prevent carrier injection in the insulating space 440, thereby forming the first contact layer 340.

[0038] An insulating layer 500, which may be SiO2, is grown on the ridge waveguide 300. The insulating layer 500 covers the outer periphery of the ridge waveguide 300 and the inner wall of the processing groove 450, filling the insulating space 440. The insulating layer 500 above the first contact layer 340 is removed by photolithography and etching to form a contact window. On top of the insulating layer 500, a specific pattern is photolithographically formed, and a covering metal layer 900 is deposited, covering the ridge waveguide 300 and the insulating layer 500. The first contact layer 340, which avoids the contact window, can form an ohmic contact with the metal layer 900, providing a current injection channel.

[0039] In some embodiments provided in this application, such as Figure 1 As shown, optionally, the semiconductor laser device 10 further includes: a buffer layer 600 and a substrate layer 700. The buffer layer 600 is connected to the bottom surface of the active module 100, and the substrate layer 700 is connected to the bottom surface of the buffer layer 600. The buffer layer 600 and the substrate layer 700 are made of the same material. The etch stop layer 410 and the buffer layer 600 extend circumferentially out of the active module 100 and form a receiving space 800. The passive waveguide 200 is located within the receiving space 800.

[0040] In this embodiment, the substrate layer 700 is located below the buffer layer 600. The substrate layer 700 can be InP, which plays a role in mechanical support and conductivity, laying the process foundation for subsequent epitaxial growth, etching, and metallization processes.

[0041] The buffer layer 600 is located below the active module 100. The buffer layer 600 can be InP. The buffer layer 600 can play the roles of lattice matching, thermal expansion coefficient matching and defect blocking.

[0042] The etching stop layer 410 and the buffer layer 600 extend circumferentially from the active module 100. When processing the passive waveguide 200, part of the outer end of the active module 100 is removed circumferentially, causing the active module 100 to shrink inward relative to the buffer layer 600. An etched region is processed circumferentially in the active module 100, forming a receiving space 800. The passive waveguide 200 is grown in the etched region, so that the passive waveguide 200 surrounds the outer periphery of the active module 100.

[0043] A second aspect of this application provides a method for manufacturing a semiconductor laser device, such as... Figure 4 As shown, the method for manufacturing the semiconductor laser device is used to manufacture the semiconductor laser device provided in any of the first aspects of the embodiments described above. The method for manufacturing the semiconductor laser device includes: Step 101: Epitaxially grow a buffer layer on the top surface of the substrate layer; Step 102: Grow an active module on the top surface of the buffer layer; Step 103: Remove part of the outer end of the active module along the circumferential direction to create a accommodating space; Step 104: Grow a passive waveguide within the containment space; Step 105: Fabricate a ridge waveguide on the top surface of the passive waveguide and the active module.

[0044] In this embodiment, a buffer layer and an active module are epitaxially grown sequentially on a substrate using Metal-organic Chemical Vapor Deposition (MOCVD). A portion of the outer end of the active module is removed circumferentially via step-by-step photolithography and wet etching, causing the active module to shrink inwards relative to the buffer layer. An etched region is formed circumferentially around the active module, creating a accommodating space. Using SiO2 as a mask, a passive waveguide is grown within the etched region, surrounding the outer periphery of the active module.

[0045] A horn-shaped ridge waveguide is fabricated on the top surface of the passive waveguide and the active module.

[0046] By setting up a horn-shaped ridge waveguide and a passive waveguide that work together, the reflected light, after being reflected to the end face of the semiconductor laser device, must pass through a section composed of the passive waveguide and the horn-shaped ridge waveguide before entering the quantum well active layer. Within this section, the reflected light contracts due to the narrowing of the ridge waveguide, which significantly reduces the mode coupling efficiency of the light wave and lowers the reverse transmittance. This reduces the amount of reflected light entering the quantum well active layer, improves the stability of the optical field within the resonant cavity, enhances the anti-reflection capability of the semiconductor laser device, meets the anti-reflection requirements of the semiconductor laser device, eliminates the need for isolators, and greatly reduces the overall manufacturing cost of the optical module.

[0047] In some embodiments provided in this application, optionally, the step of growing an active module on the top surface of the buffer layer specifically includes: growing a grating layer on the top surface of the buffer layer; growing a lower waveguide layer on the top surface of the grating layer; growing a quantum well active layer on the top surface of the lower waveguide layer; growing an upper waveguide layer on the top surface of the quantum well active layer; and growing a current-limiting layer on the top surface of the upper waveguide layer.

[0048] In this embodiment, a grating layer, a lower waveguide layer, a quantum well active layer, an upper waveguide layer, and a current-limiting layer are epitaxially grown sequentially on the top surface of the buffer layer.

[0049] The upper and lower waveguide layers confine charge carriers within the quantum well active layer and photons within the quantum well active layer, upper waveguide layer, and lower waveguide layer, increasing the optical field confinement factor, improving lattice matching, enhancing crystal epitaxial quality, and reducing the number of internal defects and non-radiative recombination centers. The grating layer acts as a mode selector, enabling the active module to operate in a single longitudinal mode, selecting specific laser modes. The current-limiting layer concentrates charge carriers within the quantum well active layer, reducing Ith and improving photoelectric conversion efficiency.

[0050] In some embodiments provided in this application, optionally, the step of fabricating a ridge waveguide on the top surface of the passive waveguide and the active module specifically includes: growing an etch stop layer on the top surface of the passive waveguide and the active module; growing a fill layer on the top surface of the etch stop layer; growing a contact layer on the top surface of the fill layer; processing two processing grooves on the fill layer and the contact layer to form a first fill layer and a second fill layer, as well as a first contact layer prototype and a second contact layer; removing the first contact layer prototype above the passive waveguide to process an insulating space, forming the first contact layer.

[0051] In this embodiment, an etch stop layer, a fill layer, and a contact layer are epitaxially grown sequentially on the top surfaces of the passive waveguide and the active module. Part of the fill layer and contact layer are removed from the wafer surface through photolithography, etching, and etching, creating two processing trenches. This divides the fill layer into a first fill layer and a second fill layer, and the contact layer into a first contact layer prototype and a second contact layer. The first fill layer is located between the two second fill layers, and the first contact layer prototype is located between the two second contact layers. Between the two processing trenches, the remaining first fill layer and first contact layer prototype form the horn shape of the ridge waveguide.

[0052] The first contact layer prototype is partially removed at both ends by photolithography and etching, that is, the first contact layer prototype above the passive waveguide is removed, and an insulating space is formed to avoid carrier injection in the insulating space, thereby forming the first contact layer.

[0053] For example, the removal length at the light-emitting end can be 30um to 50um, and the removal length at the other end can be 5um to 15um.

[0054] In some embodiments provided in this application, optionally, after the step of fabricating the insulating space, the method further includes: growing an insulating layer on the outside of the ridge waveguide; removing the insulating layer above the first contact layer to fabricate a contact window; depositing a covering metal layer on top of the first contact layer and the insulating layer; and cutting the metal layer.

[0055] In this embodiment, an insulating layer is grown on top of the outer side of the ridge waveguide, covering the outer side of the ridge waveguide and the inner wall of the processing trench, and filling the insulating space. The insulating layer above the first contact layer is removed by photolithography and etching to form a contact window. On top of the insulating layer, a specific pattern is photolithographically formed, a cover metal layer is deposited, and the metal layer is cut to form the desired shape. The first contact layer, which is avoided by the contact window, can form an ohmic contact with the metal layer, providing a current injection channel.

[0056] For example, the metal layer includes a connecting metal and a pad, the connecting metal being connected to the ridge waveguide and used to conduct the circuit. The upper surface of the pad is coplanar with the upper surface of the connecting metal, facilitating an adsorption operation when handling the semiconductor laser device.

[0057] In some embodiments provided in this application, optionally, before the step of removing the insulating layer above the first contact layer, the method further includes: removing an insulating layer of a predetermined width at both ends of the insulating layer along a direction perpendicular to laser emission. And / or after the step of cutting the metal layer, the method further includes: grinding and polishing the substrate layer to process the thickness of the semiconductor laser device to a predetermined thickness; and depositing metal on the bottom surface of the substrate layer.

[0058] In this embodiment, the insulating layer is removed by photolithography and etching on the left and right sides of the laser emission direction, respectively, leaving a cutting position to facilitate the subsequent decomposition of the wafer into grains.

[0059] The substrate is ground and polished to achieve a predetermined thickness for the semiconductor laser device, and metal for conducting circuits is deposited on the bottom surface of the substrate.

[0060] For example, the preset width can be 15um to 20um, and the preset thickness can be 90um to 110um.

[0061] In a specific embodiment, the structure of the semiconductor laser device and its fabrication method are as follows: 1. On an InP substrate, an InP buffer layer, an InGaAsP grating layer, an AlGaInAs lower waveguide layer, an AlGaInAs ALQ-quantum well active layer, an AlGaInAs upper waveguide layer, and an InAlAs current-limiting layer are epitaxially grown sequentially using a metal-organic chemical vapor deposition system.

[0062] 2. Using stepper photolithography and wet etching, a portion of the active module is removed. SiO2 is used as a mask to grow a passive waveguide in the etched area, followed by the growth of an etch stop layer, a fill layer, and a contact layer.

[0063] 3. Two 1.8µm deep processing grooves are formed on the chip surface through photolithography, etching and corrosion, leaving a ridge waveguide in the middle, and a horn-shaped waveguide is made at the light-emitting end.

[0064] 4. Remove the contact layer above the passive waveguide by photolithography and etching to prevent carrier injection at that location.

[0065] 5. Grow a SiO2 insulating layer, then use photolithography and etching to remove SiO2 from specific areas, making it easier to decompose the wafer into grains later.

[0066] 6. The SiO2 insulating layer directly above the ridge waveguide is removed by photolithography and etching to expose the contact layer.

[0067] 7. Photolithography is used to create a specific pattern, a metal layer is deposited and covered, and excess metal is removed. The metal above the ridge waveguide forms an ohmic contact with the contact layer.

[0068] 8. Grinding and polishing to reduce the chip thickness to 90um to 110um.

[0069] 9. Perform metal deposition on the back side.

[0070] This structure reduces the intensity of light reflected back to the quantum well active layer, thereby improving the output optical signal quality of the semiconductor laser device under a certain intensity of reflected light.

[0071] Three devices were actually fabricated according to this structure and anti-reflection tests were conducted. The margin (eye diagram margin) was compared with that of the conventional scheme under -12dB reflected light. The results are shown in Table 1. Table 1

[0072] The numbers in the table represent the output optical signal quality of the semiconductor laser device after a -12dB reflected light is applied. A higher number indicates a better output optical signal and stronger anti-reflection capability. The epitaxial structures of the two schemes are identical, differing only in the shape of the ridge waveguide; the ridge width of the conventional scheme remains constant at 2µm.

[0073] In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0074] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0075] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0076] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A semiconductor laser device, characterized in that, include: An active module, the active module including a quantum well active layer, the quantum well active layer being used to emit laser light; A passive waveguide surrounds the outside of the active module in the circumferential direction; A ridge waveguide is connected to the top surface of the active module and the passive waveguide. The ridge waveguide extends along the laser emission direction. The ridge waveguide includes a first conductive part and a second conductive part connected to each other. The ridge width of the second conductive part near the end of the first conductive part gradually increases along the laser emission direction and is greater than the ridge width of the first conductive part. The second conductive part is located on the light-emitting side of the active module. The second conductive part is opposite to the passive waveguide and is located outside the laser-emitting end face of the active module. An etch stop layer is connected to the top surface of the active module and the passive waveguide; The second filling layer is connected to the top surface of the etching stop layer; The ridge waveguide includes: The first filling layer is connected to the top surface of the etching stop layer. The material of the second filling layer is the same as that of the first filling layer and is located on both sides of the first filling layer. The second filling layers on both sides form processing grooves with the first filling layer respectively. The first filling layer constitutes the first conductive part and the second conductive part.

2. The semiconductor laser device according to claim 1, characterized in that, The active module also includes: The upper waveguide layer is connected to the top surface of the quantum well active layer; The lower waveguide layer is connected to the bottom surface of the quantum well active layer; The grating layer is connected to the bottom surface of the lower waveguide layer; The current-limiting layer is connected to the top surface of the upper waveguide layer and the ridge waveguide, respectively.

3. The semiconductor laser device according to claim 1, characterized in that, The ridge waveguide also includes: The first contact layer is connected to the top surface of the first filling layer. The two ends of the first contact layer along the laser emission direction respectively shrink inward to form an insulating space, and the insulating spaces on both sides are respectively opposite to the passive waveguide. The semiconductor laser device further includes: The second contact layer is connected to the top surface of the second filler layer, and the material of the second contact layer is the same as that of the first contact layer. An insulating layer is connected to the outer end face of the ridge waveguide, and a contact window is provided on the insulating layer, the contact window avoiding the first contact layer; A metal layer covers the ridge waveguide and the insulating layer, and the metal layer forms an ohmic contact with the first contact layer.

4. The semiconductor laser device according to claim 1, characterized in that, Also includes: A buffer layer is connected to the bottom surface of the active module; A substrate layer is connected to the bottom surface of the buffer layer. The buffer layer is made of the same material as the substrate layer. The etch stop layer and the buffer layer extend circumferentially from the active module and form a receiving space. The passive waveguide is located within the receiving space.

5. A method for manufacturing a semiconductor laser device, used to manufacture the semiconductor laser device as described in any one of claims 1 to 4, characterized in that, include: A buffer layer is epitaxially grown on the top surface of the substrate; An active module is grown on the top surface of the buffer layer; A portion of the outer end of the active module is removed circumferentially to create a accommodating space; A passive waveguide is grown within the accommodating space; A ridge waveguide is fabricated on the top surface of the passive waveguide and the active module.

6. The method for manufacturing a semiconductor laser device according to claim 5, characterized in that, The step of growing the active module on the top surface of the buffer layer specifically includes: A grating layer is grown on the top surface of the buffer layer; A lower waveguide layer is grown on the top surface of the grating layer; A quantum well active layer is grown on the top surface of the lower waveguide layer; A waveguide layer is grown on the top surface of the active layer of the quantum well; A current-limiting layer is grown on the top surface of the upper waveguide layer.

7. The method for manufacturing a semiconductor laser device according to claim 5, characterized in that, The step of fabricating a ridge waveguide on the top surface of the passive waveguide and the active module specifically includes: An etching stop layer is grown on the top surface of the passive waveguide and the active module; A filler layer is grown on the top surface of the etch stop layer; A contact layer is grown on the top surface of the filler layer; Two machining grooves are machined on the filling layer and the contact layer to form a first filling layer and a second filling layer, as well as a first contact layer prototype and a second contact layer. The initial sample of the first contact layer above the passive waveguide is removed, and an insulating space is fabricated to form the first contact layer.

8. The method for manufacturing a semiconductor laser device according to claim 7, characterized in that, After the step of processing the insulating space, the method further includes: An insulating layer is grown on the outside of the ridge waveguide; Remove the insulating layer above the first contact layer to create a contact window; A covering metal layer is deposited on top of the first contact layer and the insulating layer; Cut the metal layer.

9. The method for manufacturing a semiconductor laser device according to claim 8, characterized in that, Prior to the step of removing the insulating layer above the first contact layer, the method further includes: Along a direction perpendicular to laser emission, at both ends of the insulating layer, remove insulating layers of a predetermined width; and / or After the step of cutting the metal layer, the method further includes: The substrate layer is ground and polished to process the thickness of the semiconductor laser device to a preset thickness; Metal is deposited on the bottom surface of the substrate.

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