Semiconductor laser and manufacturing method thereof

Abstract

The invention relates to the technical field of semiconductor lasers, and discloses a semiconductor laser and a manufacturing method thereof.The semiconductor laser comprises an epitaxial structure and a ridge waveguide structure, and the ridge waveguide structure is arranged on the front face of the epitaxial structure; the ridge waveguide structure comprises a first section ridge, a second section ridge and a third section ridge, and one end of the first section ridge is a light emitting cavity surface. According to the semiconductor laser, a ridge waveguide structure is composed of a first section ridge, a second section ridge and a third section ridge, the ridge width of the second section ridge is designed to be different from the ridge width of the third section ridge, two transverse light wave limiting cavities with different ridge widths are manufactured, and transverse modes conforming to the two different ridge widths are screened; the ridge length of the second section of ridge is designed to be different from that of the third section of ridge, the second section of ridge and the third section of ridge form two laser resonant cavities with different lengths with the first section of ridge respectively, and longitudinal modes conforming to the two laser resonant cavities with different lengths are screened, so that the aim of conveniently regulating and controlling the transverse mode and the longitudinal mode is fulfilled; and the large-ridge-width laser can realize single-mode light spot output under high power.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor lasers, and specifically to a semiconductor laser and a manufacturing method thereof. Background Art

[0002] A semiconductor laser is an electronic device that converts electrical energy into light energy. It can generate laser beams with high intensity, high monochromaticity, and high directivity. In semiconductor lasers, the transverse mode and the longitudinal mode are two main laser modes.

[0003] The transverse mode refers to the electromagnetic wave field distributed transversely inside the laser tube. The longitudinal mode refers to the electromagnetic wave field distributed along the axial direction of the laser tube inside the laser tube. The difference between these two modes lies in the different directions of their field distributions.

[0004] Chinese Patent CN115864133A discloses a Y-shaped high-power single-mode semiconductor laser, in which a conventional ridge waveguide is gradually divided into two identical branched ridge waveguides after being guided, and the overall structure is Y-shaped. The symmetric branches on the rear side of the Y-shaped waveguide are called the symmetric arms of the Y-shaped waveguide. Through the transmission of the output light in the wide waveguide region, the gain pressure of the fundamental mode can be further enhanced, which is beneficial to the single-mode spot output of the laser at high power. This patent is achieved under the condition that the width of the ridge waveguide is 2 - 5 μm. When preparing high-power laser devices, in order to facilitate the injection of large currents to obtain greater output power, the requirement for the ridge width of the ridge waveguide will increase, and it will be difficult to control the modes of the transverse and longitudinal modes, which is not conducive to the single-mode spot output of large-ridge-width lasers at high power. Summary of the Invention

[0005] (1) Technical Problems to be Solved

[0006] In view of the deficiencies of the prior art, the present invention provides a semiconductor laser and a manufacturing method thereof, which have the advantages of transverse and longitudinal mode filtering, etc., and solve the problem that it is not conducive to the single-mode spot output of large-ridge-width lasers at high power.

[0007] (2) Technical Solutions

[0008] The transverse mode is closely related to the transverse size and shape of the laser resonator cavity. Inside the resonator cavity, the light wave is restricted transversely to form a specific transverse field distribution, that is, the transverse mode. Different transverse modes correspond to different beam qualities and energy distributions. Under the shape of a conventional rectangular ridge waveguide, the transverse mode can be adjusted by changing the ridge width.

[0009] The longitudinal mode is related to the length and refractive index of the laser resonator cavity. Inside the resonator cavity, standing waves are formed during the propagation of light waves, and each standing wave corresponds to a specific frequency and wavelength. The longitudinal mode frequency spacing of the laser can be calculated by △νq = 1 - νq = c / 2nL, where △ν is the longitudinal mode frequency spacing, q is the mode order number, c is the speed of light in a vacuum, approximately 3×10^8 m / s, n is the refractive index of the material, and L is the length of the laser resonator cavity. Under the same refractive index of the material, the longitudinal mode frequency spacing is only related to the length L of the resonator cavity.

[0010] By designing two ridge waveguides with different lengths and widths combined together, using the ridge width difference and ridge length difference of the two ridge waveguides to filter out light waves that do not conform to the transverse and longitudinal mode frequency spacings of the two ridge waveguides, compared with a single rectangular ridge waveguide, it can reduce multimode and is more conducive to achieving single-mode spot output of a large-ridge-width laser at high power.

[0011] A semiconductor laser includes an epitaxial structure and a ridge waveguide structure. The ridge waveguide structure is disposed on the front surface of the epitaxial structure; the ridge waveguide structure includes a first section of ridge, a second section of ridge, and a third section of ridge. One end of the first section of ridge is respectively connected to the second section of ridge and the third section of ridge. The other end of the first section of ridge is the light-emitting cavity surface. The ridge width of the second section of ridge is different from the ridge width of the third section of ridge, and the ridge length of the second section of ridge is different from the ridge length of the third section of ridge.

[0012] Furthermore, the ridge width a of the first section of ridge ≥ the ridge width b of the second section of ridge, and the ridge width a of the first section of ridge ≥ the ridge width d of the third section of ridge.

[0013] Furthermore, the ridge width b of the second section of ridge is different from the ridge width d of the third section of ridge, and the ridge length k of the second section of ridge is different from the ridge length j of the third section of ridge; if k > j, the difference between the ridge length k of the second section of ridge and the ridge length j of the third section of ridge is preferably (k - j) / (h + k) = (1 - 40)%, where h is the ridge length of the first section of ridge; if j > k, the difference between the ridge length k of the second section of ridge and the ridge length j of the third section of ridge is preferably (j - k) / (h + j) = (1 - 40)%. The smaller the difference between the lengths of the two ridge waveguides, the larger the common multiple of the two standing waves in the cavity, and it is more conducive to mode selection of the longitudinal mode.

[0014] Furthermore, the ridge waveguide structure is formed by etching.

[0015] Another technical problem to be solved by the present invention is to provide a manufacturing method of a semiconductor laser, including the following steps:

[0016] 1) Perform the pre-lithography preparation process for the ridge waveguide structure of the wafer;

[0017] 2) Perform lithography on the ridge waveguide structure of the wafer;

[0018] 3) Etch the ridge waveguide structure of the wafer;

[0019] 4) Repeat photolithography until the ridge waveguide structure is completed.

[0020] Furthermore, the ridge waveguide structure includes a first-segment ridge, a second-segment ridge, and a third-segment ridge.

[0021] Furthermore, the ridge width a of the first-segment ridge is ≥ the ridge width b of the second-segment ridge, and the ridge width a of the first-segment ridge is ≥ the ridge width d of the third-segment ridge.

[0022] Furthermore, the ridge width b of the second-segment ridge is different from the ridge width d of the third-segment ridge, and the ridge length k of the second-segment ridge is different from the ridge length j of the third-segment ridge.

[0023] Furthermore, the etching of the wafer ridge waveguide structure is dry etching or wet etching.

[0024] (III) Beneficial effects

[0025] Compared with the prior art, the present invention provides a semiconductor laser, which has the following beneficial effects:

[0026] In this semiconductor laser, the ridge waveguide structure is composed of a first-segment ridge, a second-segment ridge, and a third-segment ridge. By designing that the ridge width of the second-segment ridge is different from that of the third-segment ridge, two transverse optical wave confinement cavities with different ridge widths are fabricated to screen the transverse modes that conform to the two different ridge widths. By designing that the ridge length of the second-segment ridge is different from that of the third-segment ridge, and the second-segment ridge and the third-segment ridge respectively form two laser resonating cavities with different lengths with the first-segment ridge to screen the longitudinal modes that conform to the two laser resonating cavities with different lengths, the purpose of transverse and longitudinal mode filtering is achieved, which is beneficial to the single-mode spot output of a large-ridge-width laser at high power. Description of the drawings

[0027] Figure 1 It is a schematic structural diagram of a semiconductor laser of the present invention;

[0028] Figure 2 It is a front schematic structural diagram of a semiconductor laser of the present invention;

[0029] Figure 3 It is a three-dimensional diagram of a semiconductor laser of the present invention;

[0030] Figure 4 It is a schematic diagram of a deformed structure of the ridge waveguide structure of a semiconductor laser of the present invention;

[0031] Figure 5 It is a schematic diagram of another deformed structure of the ridge waveguide structure of a semiconductor laser of the present invention.

[0032] In the figure: 1 epitaxial structure, 2 ridge waveguide structure, 21 first-segment ridge, 22 second-segment ridge, 23 third-segment ridge. Detailed implementation manners

[0033] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] Embodiment 1

[0035] Please refer to Figures 1-3 , a semiconductor laser, comprising an epitaxial structure 1 and a ridge waveguide structure 2. The ridge waveguide structure 2 is disposed on the front surface of the epitaxial structure 1; the ridge waveguide structure 2 is composed of a first-segment ridge 21, a second-segment ridge 22, and a third-segment ridge 23, and the bottom surface of the first-segment ridge 21 is the light-emitting cavity surface.

[0036] In this embodiment, the ridge width a of the first-segment ridge 21 is 40 μm, the ridge width b of the second-segment ridge 22 is 20 μm, and the ridge width d of the third-segment ridge 23 is 18 μm.

[0037] In this embodiment, the ridge length h of the first-segment ridge 21 is 400 μm, the ridge length k of the second-segment ridge 22 is 800 μm, and the ridge length j of the third-segment ridge 23 is 650 μm.

[0038] In this embodiment, the ridge waveguide structure 2 is formed by dry etching.

[0039] Embodiment 2

[0040] Please refer to Figure 4 , a semiconductor laser, comprising an epitaxial structure 1 and a ridge waveguide structure 2. The ridge waveguide structure 2 is disposed on the front surface of the epitaxial structure 1; the ridge waveguide structure 2 is composed of a first-segment ridge 21, a second-segment ridge 22, and a third-segment ridge 23, and the bottom surface of the first-segment ridge 21 is the light-emitting cavity surface.

[0041] In this embodiment, the ridge width a of the first-segment ridge 21 is 40 μm, the ridge width b of the second-segment ridge 22 is 30 μm, and the ridge width d of the third-segment ridge 23 is 15 μm.

[0042] In this embodiment, the ridge length h of the first-segment ridge 21 is 400 μm, the ridge length k of the second-segment ridge 22 is 972 μm, and the ridge length j of the third-segment ridge 23 is 800 μm.

[0043] Embodiment 3:

[0044] Please refer to Figure 5, a semiconductor laser, comprising an epitaxial structure 1 and a ridge waveguide structure 2, the front surface of the epitaxial structure 1 is provided with the ridge waveguide structure 2; the ridge waveguide structure 2 is composed of a first-stage ridge 21, a second-stage ridge 22 and a third-stage ridge 23, and the bottom surface of the first-stage ridge 21 is the light-emitting cavity surface.

[0045] In this embodiment, the ridge width a of the first-stage ridge 21 is 40 μm, the ridge width b of the second-stage ridge 22 is 25 μm, and the ridge width d of the third-stage ridge 23 is 20 μm.

[0046] In this embodiment, the ridge length h of the first-stage ridge 21 is 400 μm, the ridge length k of the second-stage ridge 22 is 1000 μm, and the ridge length j of the third-stage ridge 23 is 825 μm.

[0047] The beneficial effects of the above embodiment are as follows:

[0048] For this semiconductor laser, by forming the ridge waveguide structure with the first-stage ridge 21, the second-stage ridge 22 and the third-stage ridge 23, and designing the ridge width of the second-stage ridge 22 to be different from that of the third-stage ridge 23 to fabricate two lateral optical wave confinement cavities with different ridge widths, screening the transverse modes that conform to the two different ridge widths, designing the ridge length of the second-stage ridge 22 to be different from that of the third-stage ridge 23, and forming two laser resonators with different lengths with the second-stage ridge 22 and the third-stage ridge 23 respectively with the first-stage ridge 21, screening the longitudinal modes that conform to the two laser resonators with different lengths, so as to achieve the purpose of transverse and longitudinal mode filtering, which is beneficial to the single-mode spot output of a large-ridge-width laser at high power.

[0049] For other processes after the annealing of the epitaxial wafer growth, such as: the process of forming electrodes, the process of exposure and etching, the process of forming a protective film, and the process of cleavage, etc., belong to the recognized field for those of ordinary skill in the art, and will not be elaborated too much in this article.

[0050] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirits of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A semiconductor laser, comprising an epitaxial structure (1) and a ridge waveguide structure (2), characterized in that: The front surface of the epitaxial structure (1) is provided with the ridge waveguide structure (2); the ridge waveguide structure (2) includes a first-section ridge (21), a second-section ridge (22), and a third-section ridge (23). One end of the first-section ridge (21) is respectively connected to the second-section ridge (22) and the third-section ridge (23), and the other end of the first-section ridge (21) is the light-emitting cavity surface; the ridge width of the second-section ridge (22) is different from the ridge width of the third-section ridge (23), and the ridge length of the second-section ridge (22) is different from the ridge length of the third-section ridge (23).

2. A semiconductor laser according to claim 1, characterized in that: The ridge width of the first-section ridge (21) ≥ the ridge width of the second-section ridge (22), and the ridge width of the first-section ridge (21) ≥ the ridge width of the third-section ridge (23).

3. A semiconductor laser according to claim 1, characterized in that: Let the ridge length of the first-section ridge be h, the ridge length of the second-section ridge be k, and the ridge length of the third-section ridge be j; if k > j, the difference between the ridge length k of the second-section ridge and the ridge length j of the third-section ridge is (k - j) / (h + k) = (1 - 40)%; if j > k, the difference between the ridge length k of the second-section ridge and the ridge length j of the third-section ridge is (j - k) / (h + j) = (1 - 40)%.

4. A semiconductor laser according to claim 1, characterized in that: The ridge waveguide structure (2) is formed by etching.

5. A manufacturing method of a semiconductor laser, characterized in that, It includes the following steps: 1) Perform the preparatory process before the photolithography of the ridge waveguide structure (2) on the wafer; 2) Perform the photolithography of the ridge waveguide structure (2) on the wafer; 3) Perform the etching of the ridge waveguide structure (2) on the wafer; 4) Repeat the photolithography until the ridge waveguide structure (2) is completed.

6. The manufacturing method of a semiconductor laser according to claim 5, characterized in that: The ridge waveguide structure (2) includes a first-section ridge (21), a second-section ridge (22), and a third-section ridge (23).

7. A manufacturing method of a semiconductor laser according to claim 6, characterized in that: The ridge width of the first-section ridge (21) ≥ the ridge width of the second-section ridge (22), and the ridge width of the first-section ridge (21) ≥ the ridge width of the third-section ridge (23).

8. The method for manufacturing a semiconductor laser according to claim 6, wherein: The ridge width of the second-section ridge (22) is different from the ridge width of the third-section ridge (23), and the ridge length of the second-section ridge (22) is different from the ridge length of the third-section ridge (23).

9. The manufacturing method of a semiconductor laser according to claim 5, characterized in that: The etching of the ridge waveguide structure (2) is dry etching or wet etching.

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