A laser

Abstract

The embodiment of the present application provides a laser, which comprises a waveguide type coupler, one end of the waveguide type coupler being provided with an anti-reflection film; and a waveguide structure, one end of the waveguide structure being connected to the other end of the waveguide type coupler, and the other end of the waveguide structure being provided with a high-reflection film. The present application effectively reduces the cavity surface light power density of a high-power laser.

Description

Technical Field

[0001] This application relates to the field of semiconductors, and more specifically, to a laser. Background Technology

[0002] Semiconductor lasers are lasers that use semiconductor materials as their working medium. They have many advantages such as small size, high efficiency, long lifespan, and easy integration, and are therefore widely used in fields such as imaging, communication, and machining. Manufacturing high-power, high-beam-quality, and narrow-linewidth semiconductor lasers has always been a goal pursued by people.

[0003] To achieve high-efficiency single-mode fiber coupling, it is necessary to fabricate a single-fundamental transverse-mode laser with high power output. However, in order to ensure stable fundamental transverse-mode operation, the emission stripe width of the semiconductor laser must be narrow enough. A narrow emission stripe width greatly limits the optical output power and leads to extremely high optical power density at the exit cavity surface, which in turn makes it easy to cause optical catastrophic mirror damage. Summary of the Invention

[0004] The purpose of this application is to provide a laser that effectively reduces the surface area power density of a high-power laser.

[0005] The first aspect of this application provides a laser, including: a waveguide coupler, one end of which is provided with an anti-reflection film; and a waveguide structure, one end of which is connected to the other end of the waveguide coupler, the other end of which is provided with a high-reflection film.

[0006] In one embodiment, the laser further includes a straight waveguide disposed between the waveguide structure and the waveguide coupler.

[0007] In one embodiment, the waveguide coupler is configured with a trapezoidal input port at the end without the anti-reflection membrane.

[0008] In one embodiment, the side tilt angle of the trapezoidal input port ranges from 1° to 45°.

[0009] In one embodiment, the straight waveguide has a ridge structure, and the ridge width of the straight waveguide ranges from 2 μm to 10 μm.

[0010] In one embodiment, the length of the straight waveguide ranges from 0 μm to 500 μm.

[0011] In one embodiment, the width of the waveguide coupler is greater than the width of the straight waveguide.

[0012] In one embodiment, the waveguide structure is a ridge structure, and the width of the waveguide structure gradually increases along the direction close to the high-reflectivity film.

[0013] In one embodiment, the length of the waveguide coupler ranges from 0.6L' to L', where L' is the distance from the input port of the waveguide coupler to the first self-image.

[0014] In one embodiment, the central axis of the waveguide coupler and the central axis of the waveguide structure are aligned. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of a laser according to an embodiment of this application;

[0017] Figure 2 This is a schematic diagram of the structure of a laser according to an embodiment of this application;

[0018] Figure 3 This is a partial structural schematic diagram of a waveguide structure according to an embodiment of this application;

[0019] Figure 4 This is a partial structural schematic diagram of a waveguide structure according to an embodiment of this application;

[0020] Figure 5 This is a partial structural schematic diagram of a waveguide structure according to an embodiment of this application;

[0021] Figure 6 This is a partial structural schematic diagram of a waveguide coupler according to an embodiment of this application;

[0022] Figure 7 This is a contour map of the light field intensity distribution according to an embodiment of this application;

[0023] Figure 8 This is a contour map of the light field intensity distribution according to an embodiment of this application.

[0024] Figure label:

[0025] 10-Laser, 11-Waveguide coupler, 12-Anti-reflection coating, 13-Waveguide structure, 14-High-reflection coating, 15-Straight waveguide, 16-Trench, 17-First self-image. Detailed Implementation

[0026] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0027] In the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and do not indicate a sequence number, nor should they be construed as indicating or implying relative importance.

[0028] In the description of this application, terms such as "horizontal," "vertical," and "hanging" do not imply that the component is required to be absolutely horizontal or hanging, but rather that it may be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0029] In the description of this application, the terms "upper", "lower", "left", "right", "front", "back", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the product of this application is usually placed in when in use. They are only for the convenience of describing this application and do not indicate or imply that the device or element 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 application.

[0030] In the description of this application, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0031] Please refer to Figure 1 This is a schematic diagram of the structure of a laser 10 according to an embodiment of this application. The laser 10 includes a waveguide coupler 11, a waveguide structure 13, and a straight waveguide 15, wherein both the waveguide structure 13 and the straight waveguide 15 are ridge structures, and the width of the waveguide coupler 11 is greater than the width of the straight waveguide 15. One end of the waveguide coupler 11 is provided with an anti-reflection film 12, and the other end of the waveguide coupler 11 is connected to one end of the straight waveguide 15. The other end of the straight waveguide 15 is connected to one end of the waveguide structure 13, and the other end of the waveguide structure 13 is provided with a high-reflection film 14.

[0032] In one embodiment, the material system of the laser 10 includes, but is not limited to, InP, GaAs, GaN, GaSb, etc. The epitaxial layer structure of the laser 10, from bottom to top, includes a substrate, a lower confinement layer, a quantum well, an upper confinement layer, and an ohmic contact layer. The ridge waveguide structures of the waveguide structure 13 and the straight waveguide 15 can be achieved by dry etching or wet etching of the P-type doped material above the quantum well of the epitaxial layer structure. To ensure reliability, the ridge waveguide is not etched into the quantum well.

[0033] In one embodiment, when current is injected at the waveguide coupler 11, the waveguide coupler 11, waveguide structure 13, and straight waveguide 15 are not etched into the quantum well. When no current is injected at the waveguide coupler 11, neither the waveguide structure 13 nor the straight waveguide 15 are etched into the quantum well. The waveguide coupler 11 may not be etched into the quantum well, may be etched into the quantum well, or may be further etched into the lower confinement layer.

[0034] In one embodiment, the ridge width of the straight waveguide 15 ranges from 2 μm to 10 μm; in another embodiment, the ridge width of the straight waveguide 15 ranges from 3 μm to 6 μm; the length of the straight waveguide ranges from 0 μm to 500 μm; and in yet another embodiment, the length of the straight waveguide is less than 50 μm.

[0035] In one embodiment, the ridge width of waveguide structure 13 is equal to the ridge width of straight waveguide 15.

[0036] In one embodiment, the width of the waveguide structure 13 gradually increases along the direction close to the high-reflectivity film 14, thereby increasing the current injection area and improving the output power of the laser 10.

[0037] In one embodiment, the width of the waveguide coupler 11 is greater than the width of the straight waveguide 15. The width of the waveguide coupler 11 can vary from 3 μm to 100 μm. In another embodiment, the width of the waveguide coupler 11 varies from 4 μm to 20 μm.

[0038] In one embodiment, the waveguide structure 13 has current injection to provide gain for the lasing of the laser 10. The straight waveguide 15 and the waveguide coupler 11 have no current injection and are absorption regions. To ensure that there is no current injection in the regions of the straight waveguide 15 and the waveguide coupler 11, it is necessary to remove the highly p-type doped ohmic contact layer in this region. This can be achieved by dry etching or wet etching of the uppermost material of the epitaxial layer structure. The etching depth is 50 nm to 2 μm. In one embodiment, the etching depth is 100 nm to 600 nm.

[0039] In one embodiment, the waveguide coupler 11 can be an MMI (Multimode Interference) coupler. A multimode interference coupler utilizes the SIE (Self Imaging Effect) principle of light to achieve the function of beam splitting and combining optical power. The distance period of the self-image of the multimode interference coupler... Where λ is the wavelength, W e n is the equivalent width of the fundamental mode in a multimode waveguide. r Given the equivalent refractive index, the width of the multimode waveguide is W. For waveguides with high refractive index differences, W... e ≈W; For waveguides with low refractive index differences, W eSlightly larger than W.

[0040] In one embodiment, the central axis of the waveguide coupler 11 is aligned with the central axis of the waveguide structure 13, and the distance from the input port of the waveguide coupler 11 to the first self-image 17 becomes L / 4.

[0041] In one embodiment, the length L1 of the waveguide coupler 11 ranges from 0.6L' to L', and in another embodiment, the length L1 of the waveguide coupler 11 ranges from 0.7L' to 0.95L', where L' is the distance from the input port of the waveguide coupler 11 to the first self-image 17. This allows the first self-image 17 of the waveguide coupler 11 to occur after the output end face of the laser 10. Furthermore, since the laser continues to form the first self-image 17 of the waveguide coupler 11 after exiting the output end face, i.e., forming the same fundamental transverse mode optical field distribution as the input end of the waveguide coupler 11, the fiber coupling efficiency will not decrease due to the increase of the ridge width of the waveguide structure 13.

[0042] In one embodiment, the length of the straight waveguide 15 is zero, that is, the laser 10 does not include the straight waveguide 15, but is composed of a waveguide coupler 11 and a waveguide structure 13. The anti-reflection film 12 is disposed at one end of the waveguide coupler 11, one end of the waveguide structure 13 is connected to the other end of the waveguide coupler 11, and the high-reflection film 14 is disposed at the other end of the waveguide structure 13.

[0043] In one embodiment, the reflectivity of the antireflective film 12 is less than 5%; in another embodiment, the reflectivity of the antireflective film 12 is less than 2.5%; the reflectivity of the high reflectivity film 14 is not less than 80%; and in another embodiment, the reflectivity of the high reflectivity film 14 is greater than 90%.

[0044] like Figure 2 The diagram shown is a schematic representation of a laser 10 according to an embodiment of this application. The laser 10 includes a waveguide coupler 11, a waveguide structure 13, and a straight waveguide 15. One end of the waveguide coupler 11 is provided with an anti-reflection film 12, and the other end of the waveguide coupler 11 is connected to one end of the straight waveguide 15. The waveguide structure 13 is disposed at the other end of the straight waveguide 15, and a trench 16 is provided between the straight waveguide 15 and the waveguide structure 13. A high-reflection film 14 is provided at the end of the waveguide structure 13 away from the trench 16.

[0045] In one embodiment, the trench 16 is etched downward from the ohmic contact layer, and the etching depth can range from greater than 200 nm to the depth above the quantum well. The width of the trench along the direction of the waveguide structure 13 can be from 0.5 μm to 50 μm. In one embodiment, the width of the trench along the direction of the waveguide structure 13 can be from 2 μm to 20 μm.

[0046] In one embodiment, waveguide structure 13 has current injection, waveguide coupler 11 and straight waveguide 15 have no current injection, and trench 16 can increase electrical isolation effect and further reduce current diffusion.

[0047] In one embodiment, current is injected into the waveguide structure 13, the straight waveguide 15, and the waveguide coupler 11. The ohmic contact layer of the epitaxial layer structure is retained. However, in order to reduce the optical loss or optical gain in the regions of the straight waveguide 15 and the waveguide coupler 11, the magnitude of the injected current in the regions of the straight waveguide 15 and the waveguide coupler 11 should be near the transparent current. Furthermore, a trench 16 is provided between the waveguide structure 13 and the straight waveguide 15. The highly conductive ohmic contact layer at the trench 16 is etched so that the injected current at the waveguide structure 13 does not enter the regions of the straight waveguide 15 and the waveguide coupler 11, thereby ensuring electrical isolation.

[0048] In one embodiment, the laser 10 does not include a straight waveguide 15, but is composed of a waveguide coupler 11 and a waveguide structure 13. An anti-reflection film 12 is disposed at one end of the waveguide coupler 11, and the waveguide structure 13 is disposed at the other end of the waveguide coupler 11. A groove 16 is disposed between the waveguide structure 13 and the waveguide coupler 11, and a high-reflection film 14 is disposed at the end of the waveguide structure 13 away from the groove 16.

[0049] like Figure 3 The diagram shown is a partial structural schematic of a waveguide structure 13 according to an embodiment of this application. The waveguide structure 13 is a tapered structure, with a high-reflectivity film 14 disposed at one end. The width of the waveguide structure 13 gradually increases along the direction approaching the high-reflectivity film 14, thereby increasing the current injection region and improving the output power of the laser 10. In one embodiment, the width of the end of the waveguide structure 13 with the high-reflectivity film 14 ranges from 3 μm to 100 μm; in another embodiment, the width of the end of the waveguide structure 13 with the high-reflectivity film 14 ranges from 6 μm to 15 μm.

[0050] In one embodiment, the waveguide structure 13 may be partially or entirely tapered. In one embodiment, the boundary line of the waveguide structure 13 may be as follows: Figure 3 The straight line shown can be as follows: Figure 4 The curve shown can also be as follows: Figure 5 The broken line shown.

[0051] like Figure 6 The diagram shown is a partial structural schematic of a waveguide coupler 11 according to an embodiment of this application. One end of the waveguide coupler 11 connected to the straight waveguide 15 is a trapezoidal input port, and the side tilt angle θ of the trapezoidal input port ranges from 1° to 45°. The trapezoidal input port can prevent reflections caused by the coating at the output port of the waveguide coupler 11 from affecting multimode interference.

[0052] like Figure 7 As shown, it is a contour plot of the intensity distribution of the mode interference optical field in an embodiment of this application. The multimode interference waveguide has a width of 3μm and a length of 30μm. The ridge waveguide has a width of 2μm and a length of 1μm in the simulation. The dashed box represents the area where the multimode interference effect is almost complete, at which point the optical field energy begins to converge. Figure 8 For devices with the same structure, when the multimode interference waveguide is cleaved into a length of 24μm and coated with an anti-reflection film with a reflectivity close to 0, the contour lines of the light field intensity distribution are simulated. It can be seen that the light field energy at the output end face has a relatively wide distribution, and the light field energy re-converges into the air after propagating out of the output end face at a certain distance from the end face.

[0053] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A laser, characterized by, The application relates to a waveguide type coupler, which comprises: a waveguide structure, one end of which is connected to the other end of the waveguide type coupler, and the other end of which is provided with a high-reflection film; wherein the waveguide type coupler is a multimode interference coupler; The length of the waveguide type coupler ranges from 0.7 to 0.95 wherein, is the distance from the input port of the waveguide type coupler to the first self-image. a groove is arranged between the waveguide structure and the waveguide type coupler. The central axis of the waveguide type coupler and the central axis of the waveguide structure are arranged coincidently, the distance from the input port of the waveguide type coupler to the first self-image is L / 4; The distance period of the self-imaging of the multimode interference coupler where λ is the wavelength, is the effective width of the fundamental mode in the multimode waveguide, is the effective index, the width of the multimode waveguide is W, for a waveguide with a high index contrast, ≈ W; for a waveguide with a low index contrast, is slightly larger than W; The application further relates to a waveguide type coupler, which comprises:

2. The laser of claim 1, wherein, a straight waveguide arranged between the waveguide structure and the waveguide type coupler. The end of the waveguide type coupler, which is not provided with the anti-reflection film, is a trapezoidal input port.

3. The laser of claim 1, wherein, The side of the trapezoidal input port is inclined at an angle ranging from 1 DEG to 45 DEG.

4. The laser of claim 3, wherein, The straight waveguide is a ridge type structure, and the width of the ridge of the straight waveguide ranges from 2 mu m to 10 mu m.

5. The laser of claim 2, wherein, The length of the straight waveguide ranges from 0 mu m to 500 mu m.

6. The laser of claim 2, wherein, The width of the waveguide type coupler is greater than that of the straight waveguide.

7. The laser of claim 2, wherein, The waveguide structure is a ridge type structure, and the width of the waveguide structure gradually increases along the direction close to the high-reflection film.

8. The laser of claim 1, wherein, ​

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