Small-divergence-angle anti-reflection laser

Abstract

The utility model provides a small-divergence-angle anti-reflection laser. The small-divergence-angle anti-reflection laser comprises a substrate; the active region is formed on the substrate; the etching region is positioned on the light emitting end surface of the active region and comprises a divergence angle improving layer; the cladding extends along the light emitting direction of the active region; the metal contact layer covers the cladding layer above the active region; the isolation layer covers the cladding layer above the etching region; and an N-metal layer and a P-metal layer, the N-metal layer covers the back surface of the substrate, and the P-metal layer covers the metal contact layer and the isolation layer. Through the arrangement of the isolation layer, current injection into the end face can be limited, the light emitting power density of the end face can be reduced, the non-radiative recombination process can be inhibited, the temperature of the end face is reduced in the area, optical catastrophe damage can be reduced, and the service life of the laser can be prolonged.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor manufacturing technology, and in particular to a small divergence angle anti-reflection laser. Background Technology

[0002] Small divergence angle antireflective lasers—a solution for improving fiber coupling efficiency, eliminating isolators, and reducing packaging costs—have wide applications in fiber optic communication networks.

[0003] One of the key technical challenges facing high-speed direct-modulation lasers in fiber optic communication networks is improving the divergence angle and beam quality. Common methods to address this challenge include using an epitaxial mode extension layer or integrating an SSC waveguide using SAG technology; however, both of these methods degrade laser performance.

[0004] Furthermore, during signal transmission, feedback light from interfaces such as optical components and suspended fiber optic ends enters the chip, causing resonant perturbations within the laser cavity and significantly reducing the transmission characteristics of high-speed optical signals. Expensive optical isolators must be introduced during packaging to address the bit error rate caused by reflections; therefore, improving the anti-reflection performance of the light source is particularly urgent. Utility Model Content

[0005] The purpose of this invention is to provide a small divergence angle anti-reflection laser to solve one or more problems existing in the prior art.

[0006] To solve this problem, this utility model provides a small divergence angle anti-reflection laser, comprising:

[0007] Substrate;

[0008] Active regions formed on the substrate;

[0009] An etching region located on the light-emitting end face of the active region, the etching region including a divergence angle improvement layer;

[0010] A cladding layer, wherein the cladding layer extends along the light emission direction of the active region;

[0011] A metal contact layer covers the cladding above the active region;

[0012] An isolation layer covering the cladding layer above the etched area; and,

[0013] An N-metal layer and a P-metal layer, wherein the N-metal layer covers the back side of the substrate, and the P-metal layer covers the metal contact layer and the isolation layer.

[0014] Optionally, in the small divergence angle antireflective laser, the etched area has a wedge-shaped groove, the side of the wedge-shaped groove away from the active area is open, and the side of the wedge-shaped groove near the active area is set at an angle to the light emission direction of the active area.

[0015] Optionally, in the small divergence angle antireflective laser, the isolation layer partially covers the metal contact layer to form an overlapping area.

[0016] Optionally, in the small divergence angle antireflective laser, the length of the overlapping region in the light-emitting direction of the active region is 0.2 μm to 5 μm.

[0017] Optionally, in the small divergence angle antireflective laser, the active region includes a first transition layer, a first confinement layer, an active layer, a second confinement layer, a second transition layer, and a grating layer formed within the second transition layer, which are formed sequentially from bottom to top.

[0018] Optionally, in the small divergence angle antireflection laser, the top surface of the divergence angle improvement layer is flush with the top surface of the grating layer, and the bottom surface height of the divergence angle improvement layer is located between the top surface height and the bottom surface height of the active layer.

[0019] Optionally, in the small divergence angle antireflection laser, the etched area further includes a first buffer layer and a second buffer layer, wherein the first buffer layer, the divergence angle improvement layer and the second buffer layer are formed sequentially from bottom to top;

[0020] The bottom surface of the first buffer layer is located between the top surface and bottom surface of the first transition layer, and the top surface of the second buffer layer is flush with the top surface of the second transition layer.

[0021] Optionally, in the small divergence angle antireflective laser, the first buffer layer and the first transition layer are made of the same material, and / or the second buffer layer and the cladding layer are made of the same material.

[0022] Optionally, in the small divergence angle antireflective laser, the first buffer layer and the second buffer layer are made of InP.

[0023] Optionally, in the small divergence angle antireflective laser, the material of the divergence angle improvement layer is InGaAsP.

[0024] Optionally, in the small divergence angle antireflective laser, the length of the etched region in the light-emitting direction of the active region is 5 μm to 20 μm.

[0025] In summary, the small divergence angle antireflective laser provided by this invention includes: a substrate; an active region formed on the substrate; an etched region located at the light-emitting end face of the active region, the etched region including a divergence angle improvement layer; a cladding layer extending along the light-emitting direction of the active region; a metal contact layer covering the cladding layer above the active region; an isolation layer covering the cladding layer above the etched region; and an N-metal layer and a P-metal layer, the N-metal layer covering the back side of the substrate, and the P-metal layer covering the metal contact layer and the isolation layer. By providing the isolation layer, current injection into the end face can be limited, the light-emitting power density at the end face can be reduced, and non-radiative recombination processes can be suppressed, resulting in a lower end face temperature in this region. Therefore, optical catastrophic damage can be reduced, and the laser lifetime can be extended.

[0026] Furthermore, the small divergence angle anti-reflection laser provided by this utility model has a ridge waveguide structure. The etched area between two adjacent cladding layers has a wedge-shaped groove. The side of the wedge-shaped groove away from the active region is open. The side of the wedge-shaped groove close to the active region is set at an angle to the light output direction of the active region. By setting the wedge-shaped groove, the crosstalk of external feedback light to the laser can be reduced, thus improving the stability of the laser. Attached Figure Description

[0027] Figure 1 A three-dimensional structural schematic diagram of a small divergence angle anti-reflection laser provided for an embodiment of this utility model;

[0028] Figure 2 A schematic diagram of the AA cross-section structure of the small divergence angle antireflective laser provided in this embodiment of the utility model;

[0029] Figure 3 An imaging schematic diagram of the far-field spot of a small divergence angle antireflective laser provided for an embodiment of this utility model;

[0030] The labels in the accompanying drawings are explained as follows:

[0031] 10-Substrate; 11-First transition layer; 12-First confinement layer; 13-Active layer; 14-Second confinement layer; 15-Raster layer; 21-Second transition layer; 31-First buffer layer; 32-Difference angle improvement layer; 33-Second buffer layer; 41-Cladding layer; 42-Metal contact layer; 51-Isolation layer; 52-P-Metal layer; 53-N-Metal layer; 61-Wedge groove. Detailed Implementation

[0032] The small divergence angle anti-reflection laser provided by this utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and use non-precise scales, only for the purpose of conveniently and clearly illustrating the embodiments of this utility model. Furthermore, the structures shown in the drawings are often part of the actual structure. In particular, different figures need to show different emphases, and sometimes different scales are used. It should be understood that relative terms such as "above," "below," "top," "bottom," and "upper" shown in the drawings can be used to describe the relationships between various elements. These relative terms are intended to cover different orientations of elements other than those depicted in the drawings. For example, if the device is inverted relative to the view in the drawings, an element described as "above" another element will now be below that element. It should also be understood that, unless specifically stated or indicated, the terms "first," "second," "third," etc., in the specification are only used to distinguish the various components, elements, steps, etc., in the specification, and are not used to indicate logical or sequential relationships between the various components, elements, steps, etc.

[0033] Please see Figure 1 and Figure 2 This utility model provides a small divergence angle reflective laser, comprising:

[0034] Substrate 10;

[0035] Active regions formed on the substrate 10;

[0036] An etched area located on the light-emitting end face of the active region, the etched area including a divergence angle improvement layer 32;

[0037] Cladding 41, the cladding 41 being along the light emission direction of the active region (i.e. Figure 2 The width direction shown in the figure indicates the extension setting;

[0038] A metal contact layer 42 covers the cladding 41 above the active region;

[0039] An isolation layer 51 covers the cladding layer 41 above the etched area; and,

[0040] N-metal layer 53 and P-metal layer 52, wherein N-metal layer 53 covers the back side of substrate 10 and P-metal layer 52 covers metal contact layer 42 and isolation layer 51.

[0041] In the small divergence angle antireflection laser provided in this embodiment, the isolation layer can limit the current injection into the end face, reduce the output power density of the end face, suppress the nonradiative recombination process, and reduce the end face temperature in this region. Therefore, it can reduce optical catastrophic damage and extend the laser life.

[0042] In this embodiment, the active region may include a first transition layer 11, a first confinement layer 12, an active layer 13, a second confinement layer 14, a second transition layer 21 formed sequentially from bottom to top on the substrate 10, and a grating layer 15 formed in the second transition layer 21.

[0043] As an example, in this embodiment, the substrate 10 is made of InP and its doping type is N-type.

[0044] The first transition layer 11 is used to alleviate the lattice mismatch between the substrate 10 and the epitaxial layer and improve the epitaxial quality. The first transition layer 11 is made of a material that matches the lattice of the substrate 10 and the active region material. In this embodiment, the material of the first transition layer 11 can be InP, and its doping type is N-type.

[0045] The first confinement layer 12 serves as both an optical confinement layer and a carrier confinement layer, providing electrons. The material of the first confinement layer 12 is a material with a significantly different refractive index from the active region material. In this embodiment, the material of the first confinement layer 12 can be a graded-component InGaAlAs with N-type doping.

[0046] The active layer 13 is the core region in the device where the main electrical or optical processes occur, and is typically composed of multiple layers of semiconductor materials, such as quantum wells, heterojunctions, or PN junctions. In this embodiment, the active layer 13 may be an InGaAlAs multilayer quantum well.

[0047] The second confinement layer 14 also serves as an optical confinement layer and a carrier confinement layer, providing holes. The material of the second confinement layer 14 is also a material with a significantly different refractive index from the active region material, such as graded-component InGaAlAs, but with p-type doping. The first confinement layer 12 and the second confinement layer 14 together form an optical waveguide, confining carriers and photons within the active region and improving device efficiency.

[0048] The second transition layer 21 is used to relieve stress between the second confinement layer 14 and the cladding layer 41, thereby improving epitaxial quality. The second transition layer 21 is made of a material that matches the crystal structure of the second confinement layer 14 and the cladding layer 41. For example, the material of the first transition layer 11 can be InP, with a p-type doping type.

[0049] The cladding 41 is used to further confine the optical field and charge carriers, improving the optical and electrical performance of the device. The cladding 41 is made of a material with a significantly different refractive index from the active region material, such as InP.

[0050] It should be noted that in this embodiment, the material of the substrate 10 is InP to describe the materials of each film layer in the active region and the cladding 41. In other embodiments, the material of the substrate 10 may also be GaAs, InAs, etc., and the materials of each film layer in the active region and the cladding 41 are selected according to the material of the substrate 10.

[0051] The etched area is formed by forming each film layer of the active region on the substrate 10 and then etching each film layer. Preferably, the length of the etched area in the light emission direction of the active region is 5~20μm.

[0052] In this embodiment, in addition to the divergence angle improvement layer 32, the etched area also includes a first buffer layer 31 and a second buffer layer 32, which are formed sequentially from bottom to top.

[0053] The thicknesses of the first buffer layer 31, the divergence angle improvement layer 32, and the second buffer layer 33 are adjusted according to the thickness of each layer in the active region. For example, the thickness of the divergence angle improvement layer 32 can be 80 nm to 400 nm, the thickness of the first buffer layer 31 can be 100 nm to 300 nm, and the thickness of the second buffer layer 33 can be 10 nm to 150 nm. When the thicknesses of the first buffer layer 31, the divergence angle improvement layer 32, and the second buffer layer 33 are adjusted according to the thickness of each layer in the active region, preferably, the top surface of the divergence angle improvement layer 32 is flush with the top surface of the grating layer 15, and the bottom surface height of the divergence angle improvement layer 32 is between the top surface height and the bottom surface height of the active layer 13. The bottom surface height of the first buffer layer 31 is between the top surface height and the bottom surface height of the first transition layer 11, and the top surface of the second buffer layer 33 is flush with the top surface of the second transition layer 21.

[0054] The first buffer layer 31 and the first transition layer 11 can be made of the same material, and the second buffer layer 33 and the cladding layer 41 can be made of the same material. Therefore, in this embodiment, the first buffer layer 31 and the second buffer layer 33 are also made of InP. Preferably, the divergence angle improving layer 32 is made of a material that is not easily oxidized, such as InGaAsP.

[0055] The laser beam typically propagates near the edge of the laser or the etched area. The divergence improvement layer 32 in the etched area has a different material refractive index than the first buffer layer 31 and the second buffer layer 33, which modifies the beam in this area and thus improves the beam quality of the laser.

[0056] In this example, preferably, the etched area located between two adjacent cladding layers 41 has a wedge-shaped groove 61. The side of the wedge-shaped groove 61 away from the active region is open, and the side of the wedge-shaped groove 61 close to the active region is angled to the light emission direction of the active region. Feedback light from interfaces such as optical elements and suspended fiber end faces affects the stability and output characteristics of the laser. The wedge-shaped groove 61 can effectively block about 30% of the feedback light, thus improving the laser's stability. Moreover, since the wedge-shaped groove 61 is only located in the etched area, it can effectively block feedback light while preventing etching damage from affecting the active region.

[0057] Preferably, the isolation layer 51 partially overlaps the metal contact layer 42 to form an overlapping region, thereby ensuring that the etched region is a non-current injection region. More preferably, the length of the overlapping region in the light-emitting direction of the active region is 0.2 μm to 5 μm.

[0058] Optionally, the thickness of the isolation layer 51 can be 150 nm to 500 nm, which can be adjusted as needed. The material of the isolation layer 51 can be a dielectric material such as SiO2 or Si3N4.

[0059] In the actual manufacturing process, a metal contact layer 42 covering the cladding layer 41 can be formed first, and then the metal contact layer 42 can be selectively etched to expose the area of ​​the cladding layer 41 above the etched area. Then, an isolation layer 51 can be formed in the exposed area of ​​the cladding layer 41 and extend to the surface covering the metal contact layer 42. Alternatively, the metal contact layer 42 can be formed only in the area of ​​the cladding layer 41 above the active area, and then an isolation layer 51 can be formed in the area of ​​the cladding layer 41 above the etched area and extend to the surface covering the metal contact layer 42.

[0060] In this embodiment, the P-metal layer 52 is formed by first depositing a Ge / Au / Ni / Au multilayer metal on the metal contact layer 42 and the isolation layer 51, and then forming an ohmic contact through annealing. The N-metal layer 53 is formed by first depositing a Ti / Au multilayer metal on the N-type substrate 10, and then forming an ohmic contact through annealing.

[0061] Figure 3 This is a schematic diagram of the far-field spot imaging of the small divergence angle antireflective laser provided in this embodiment, where the vertical axis Intensity represents light intensity, and the horizontal axes Fv and Fh represent angles in two orthogonal directions. Figure 3As can be seen, the far-field spot of the small divergence angle anti-reflection laser provided in this embodiment is a near-circular spot (26°*26.3°), while the far-field spot of a conventional laser is elliptical (approximately 25°*35°). The comparison shows that the small divergence angle anti-reflection laser provided in this embodiment has a significant improvement in divergence angle.

[0062] In summary, the small divergence angle anti-reflection laser provided by this utility model embodiment can not only improve the divergence angle and enhance the beam quality, but also improve the performance and reliability of the laser.

[0063] It should be noted that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the present invention without departing from the scope of the present invention, or equivalent embodiments can be modified based on the disclosed technical content. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A small divergence angle anti-reflection laser, characterized in that, include: Substrate; Active regions formed on the substrate; An etching region located on the light-emitting end face of the active region, the etching region including a divergence angle improvement layer; A cladding layer, wherein the cladding layer extends along the light emission direction of the active region; A metal contact layer covers the cladding above the active region; An isolation layer covering the cladding layer above the etched area; and, An N-metal layer and a P-metal layer, wherein the N-metal layer covers the back side of the substrate, and the P-metal layer covers the metal contact layer and the isolation layer.

2. The small divergence angle anti-reflection laser as described in claim 1, characterized in that, The etched area has a wedge-shaped groove, which is open on the side away from the active area, and the side of the wedge-shaped groove closest to the active area is set at an angle to the light emission direction of the active area.

3. The small divergence angle anti-reflection laser as described in claim 1, characterized in that, The isolation layer and the metal contact layer partially overlap to form an overlapping area.

4. The small divergence angle anti-reflection laser as described in claim 3, characterized in that, The length of the overlapping region in the light-emitting direction of the active region is 0.2 μm to 5 μm.

5. The small divergence angle anti-reflection laser as described in claim 1, characterized in that, The active region includes, from bottom to top, a first transition layer, a first confinement layer, an active layer, a second confinement layer, a second transition layer, and a grating layer formed within the second transition layer.

6. The small divergence angle anti-reflection laser as described in claim 5, characterized in that, The top surface of the divergence angle improvement layer is flush with the top surface of the grating layer, and the bottom surface height of the divergence angle improvement layer is located between the top surface height and the bottom surface height of the active layer.

7. The small divergence angle anti-reflection laser as described in claim 5, characterized in that, The etched area further includes a first buffer layer and a second buffer layer, wherein the first buffer layer, the divergence angle improvement layer and the second buffer layer are formed sequentially from bottom to top; The bottom surface of the first buffer layer is located between the top surface and bottom surface of the first transition layer, and the top surface of the second buffer layer is flush with the top surface of the second transition layer.

8. The small divergence angle anti-reflection laser as described in claim 7, characterized in that, The first and second buffer layers are made of InP.

9. The small divergence angle anti-reflection laser as described in claim 1, characterized in that, The material used for the divergence angle improvement layer is InGaAsP.

10. The small divergence angle anti-reflection laser as described in claim 1, characterized in that, The length of the etched area in the light-emitting direction of the active region is 5μm to 20μm.

Images