Patterned light outlet coating method of horizontal cavity surface emitting semiconductor laser

Abstract

The invention relates to the field of semiconductor lasers, in particular to a graphical light outlet coating method of a horizontal cavity surface emitting semiconductor laser, which comprises the following steps of: S1, drawing a corresponding graphical coating plate layout according to a light outlet area structure of the horizontal cavity surface emitting semiconductor laser; s2, carrying out trepanning processing on the base material according to the graphical film-coated plate layout to form a graphical film-coated plate; s3, aligning the light emitting area structure of the horizontal cavity surface emitting semiconductor laser with the graphical film coating plate through a high-temperature-resistant magnet, and then fixing the aligned horizontal cavity surface emitting semiconductor laser and graphical film coating plate on a film coating clamp, and putting the whole body into a coating machine to coat a light emitting area of the horizontal cavity surface emitting semiconductor laser, so as to form a graphical antireflection film. According to the horizontal cavity surface emitting laser, the antireflection film is plated in the light emitting area, the light efficiency and the output power of the horizontal cavity surface emitting laser can be effectively improved, and due to the fact that a DBR reflection structure does not need to be introduced, the process difficulty and diffraction loss can be effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor lasers, and in particular relates to a method for coating a patterned light outlet of a horizontal cavity surface emitting semiconductor laser. Background Art

[0002] Semiconductor lasers have the advantages of high efficiency, small size, light weight, multiple wavelengths and direct electric drive. They are the core light sources of applications such as "Digital China" and "Healthy China". They play an important role in basic and strategic industries such as intelligent manufacturing, information networks, and medical health, and make significant contributions to the national economy and national defense construction. At present, commercial semiconductor lasers mainly use edge-emitting semiconductor lasers, but there are problems such as optical catastrophic damage to the cavity surface, difficulty in power increase, elliptical spot in the light-emitting area, uneven distribution of the fast and slow axis light field, large divergence angle, poor beam quality and wide line width. These problems limit its advantages in market competition.

[0003] The horizontal cavity surface emitting semiconductor laser, which uses a periodic diffraction structure to realize the surface output coupling function, has the characteristics of both the high power of edge emitting semiconductor lasers and the excellent beam quality and easy two-dimensional integration of surface emitting semiconductor lasers. Its basic working principle is: photons realize stable feedback oscillation in the resonant cavity, and the light is coupled vertically to the chip surface. The surface emission loss causes a large threshold gain difference between the main mode and the lowest order mode, eliminating mode degeneracy and realizing a single longitudinal mode lasing mode. It has the characteristics of small divergence angle, high beam quality, narrow line width, and small temperature drift. It not only improves the working efficiency of laser devices, but also simplifies the system structure and reduces the preparation and operation costs. Combined with a single transverse mode and high refractive index difference photonic crystal structure, it is expected to achieve a watt-level continuous wave working diffraction-limited power. Therefore, it proposes a feasible solution for realizing high-power, small divergence angle, and high beam quality semiconductor lasers, and is an ideal high-power and high beam quality light source.

[0004] Traditional horizontal cavity surface emitting semiconductor lasers usually increase the output power of horizontal cavity surface emitting semiconductor lasers by adding a DBR reflection structure in the opposite direction of the light emitting area to reflect the diffracted light in the opposite direction of the light emitting direction, thereby increasing the light field coupling efficiency and diffraction efficiency of the grating. However, the photons that return to the grating after reflection will increase the diffraction loss; or by increasing the area of ​​the light emitting area to achieve high output power, however, increasing the area of ​​the light emitting area will lead to lower power density and limited improvement in diffraction efficiency. Summary of the invention

[0005] In view of this, the present invention aims to provide a method for patterning light output port coating of a horizontal cavity surface emitting semiconductor laser to solve the technical problem that the traditional method of increasing the output power of a horizontal cavity surface emitting semiconductor laser increases the diffraction loss and reduces the power density.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows: A method for coating a patterned light outlet of a horizontal cavity surface emitting semiconductor laser comprises the following steps: S1: Draw the corresponding patterned coating plate layout according to the light emitting area structure of the horizontal cavity surface emitting semiconductor laser; S2: performing hole processing on the substrate according to the patterned coating plate pattern to form a patterned coating plate; S3: Align the light-emitting area structure of the horizontal-cavity surface emitting semiconductor laser with the patterned coating plate through a high-temperature resistant magnet, then fix the aligned horizontal-cavity surface emitting semiconductor laser and the patterned coating plate on a coating fixture, and then put the whole into a coating machine to coat the light-emitting area of ​​the horizontal-cavity surface emitting semiconductor laser to form a patterned anti-reflection film.

[0007] Furthermore, in step S1, when the horizontal cavity surface emitting semiconductor laser adopts a photonic crystal structure, the patterned coating plate is designed as periodically arranged circular holes; when the horizontal cavity surface emitting semiconductor laser adopts a second-order grating structure, the patterned coating plate is designed as periodically arranged rectangular holes.

[0008] Furthermore, in step S2, a laser cutting process or a laser etching process is used to perform hole opening processing on the substrate.

[0009] Furthermore, in step S2, the substrate is a stainless steel sheet.

[0010] Furthermore, step S3 specifically includes the following steps: S31: magnetically fixing the horizontal cavity surface emitting semiconductor laser and the patterned coating plate on the same surface of the high temperature resistant magnet in sequence, with the light emitting area of ​​the horizontal cavity surface emitting semiconductor laser facing the patterned coating plate; S32: using an optical microscope to align the light emitting area of ​​the horizontal cavity surface emitting semiconductor laser with the opening of the patterned coating plate, so that the horizontal cavity surface emitting semiconductor laser, the patterned coating plate and the high temperature resistant magnet form a combination; S33: Fix the assembly on a coating fixture by means of a high temperature resistant tape, and then place the coating fixture fixing the assembly into a coating machine to coat the light emitting area of ​​the horizontal cavity surface emitting semiconductor laser to form an anti-reflection film with a transmittance higher than 99.95%.

[0011] Furthermore, the film structure of the antireflection film with a transmittance greater than 99.95% is 10nmAl 2 O 3 / 51.87nmTiO 2 / 101.54nmAl 2 O 3 .

[0012] Furthermore, an electron gun is used to fully pre-melt the high and low refractive index thin film materials before coating.

[0013] Furthermore, during the coating process, O is injected into the coating machine. 2 ions and Ar ions.

[0014] Furthermore, a coating is performed on the side of the horizontal cavity surface emitting semiconductor laser opposite to the light emitting area to form a high reflective film with a reflectivity greater than 99.9%.

[0015] Furthermore, the film structure of the high-reflection film with a reflectivity greater than 99.9% is 11 pairs of quarter-wavelength Ta 2 O 5 / SiO 2 .

[0016] Compared with the prior art, the invention can achieve the following beneficial effects: The present invention can effectively improve the light efficiency and output power of the horizontal cavity surface emitting semiconductor laser by coating an anti-reflection film on the light output area of ​​the horizontal cavity surface emitting semiconductor laser. Since there is no need to introduce a DBR reflection structure, the process difficulty and diffraction loss can be effectively reduced. Since there is no need to increase the area of ​​the light-emitting region, the power density can be guaranteed not to decrease. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 It is a structural schematic diagram of a horizontal cavity surface emitting semiconductor laser based on a second-order grating structure according to an embodiment of the invention.

[0018] Figure 2 It is a flow chart of a method for coating a patterned light outlet of a horizontal cavity surface emitting semiconductor laser according to an embodiment of the invention.

[0019] Figure 3 and Figure 4 These are two schematic diagrams of designs of a graphic coated plate pattern according to an embodiment of the invention.

[0020] Figure 5 It is a schematic diagram of a theoretical design curve of an antireflection film according to an embodiment of the invention.

[0021] Figure 6 It is a schematic diagram of a theoretical design curve of a high-reflective film according to an embodiment of the invention.

[0022] Figure 7 It is a schematic diagram of a PIV curve of a horizontal cavity surface emitting semiconductor laser whose light output region is not coated with an anti-reflection film according to an embodiment of the invention.

[0023] Figure 8 It is a schematic diagram of a PIV curve of a horizontal cavity surface emitting semiconductor laser with an anti-reflection film coated on the light output area according to an embodiment of the invention.

[0024] Explanation of the reference numerals: substrate layer 1 , N-type waveguide layer 2 , active layer 3 , P-type waveguide layer 4 , second-order grating 5 , insulating layer 6 , P-type electrode 7 , N-type electrode 8 , anti-reflection film 9 , high-reflection film 10 . DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0026] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0028] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0029] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0030] The present invention provides a method for coating a patterned light outlet of a horizontal cavity surface emitting semiconductor laser, wherein the horizontal cavity surface emitting semiconductor laser can be a horizontal cavity surface emitting semiconductor laser based on a photonic crystal structure, or a horizontal cavity surface emitting semiconductor laser based on a second-order grating structure. The following is an example of a 980nm horizontal cavity surface emitting semiconductor laser based on a second-order grating structure.

[0031] like Figure 1 As shown, a horizontal cavity surface emitting semiconductor laser based on a second-order grating structure comprises a substrate layer 1, on which an N-type waveguide layer 2, an active layer 3, and a P-type waveguide layer 4 are sequentially prepared, a middle portion of the P-type waveguide layer 4 is etched to form a second-order grating 5, a region corresponding to the second-order grating 5 is a light-emitting region, both sides of the light-emitting region are gain regions, a ridge waveguide is formed on the surface of the P-type waveguide layer 4 corresponding to the two gain regions, an insulating layer 6 is prepared on the outer side of the second-order grating 5, a P-type electrode 7 is prepared on the surface of the P-type waveguide layer 4 corresponding to the two gain regions, a high-reflection film 10 is prepared on the surface of the P-type waveguide layer 4 corresponding to the light-emitting region, an N-type electrode 8 is prepared on the bottom surface of the substrate layer 1 corresponding to the two gain regions, and an anti-reflection film 9 is prepared on the bottom surface of the substrate layer 1 corresponding to the light-emitting region.

[0032] like Figure 2 As shown, the patterned light outlet coating method of the horizontal cavity surface emitting semiconductor laser provided by the present invention comprises the following steps: S1: Draw the corresponding graphic coating plate layout according to the light emitting area structure of the horizontal cavity surface emitting semiconductor laser.

[0033] When the horizontal cavity surface emitting semiconductor laser adopts a photonic crystal structure, the patterned coating plate is designed as a periodically arranged circular hole. For example, if the light outlet is a circular hole with a diameter of 3 mm, the patterned coating plate is designed as a periodically arranged circular hole with a diameter of 3 mm. Figure 3 shown.

[0034] When the horizontal cavity surface emitting semiconductor laser adopts a second-order grating structure, the patterned coating plate is designed as a periodically arranged rectangular hole. For example, the period of the second-order grating is 280nm, that is, the length of the grating is 336μm, the width of a single semiconductor laser is 500μm, and 20 semiconductor lasers form an array. Then the patterned coating plate is designed as a periodically arranged 400μm 1cm rectangle, such as Figure 4 shown.

[0035] S2: Performing hole processing on the substrate according to the patterned coating plate pattern to form a patterned coating plate.

[0036] A 0.1 mm thick 304 stainless steel sheet is selected as the substrate, and a laser cutting process or a laser etching process is used to perform hole processing on the 304 stainless steel sheet with an accuracy of ±0.01 mm. The 304 stainless steel sheet after the hole is opened is a graphic coated plate.

[0037] The graphic coating plate needs to match the coating fixture. For example, if the coating gap is 10cm, the graphic coating plate needs to be fixed in this gap, and the gap is required to be thin enough and have high flatness. During coating, the workpiece disc rotates at high speed and cannot be adjusted in micro-area. There may be differences in the radial direction of the workpiece disc, which can only be corrected with a baffle. Therefore, the graphic coating plate needs to be highly matched with the coating fixture, and the flatness must be high to make the micro-area film preparation more uniform.

[0038] S3: Align the light-emitting area structure of the horizontal-cavity surface emitting semiconductor laser with the patterned coating plate through a high-temperature resistant magnet, then fix the aligned horizontal-cavity surface emitting semiconductor laser and the patterned coating plate on a coating fixture, and then put the whole into a coating machine to coat the light-emitting area of ​​the horizontal-cavity surface emitting semiconductor laser to form a patterned anti-reflection film.

[0039] Step S3 specifically includes the following steps: S31: magnetically fix the horizontal cavity surface emitting semiconductor laser and the patterned coating plate on the same surface of the high temperature resistant magnet in sequence, and the light emitting area of ​​the horizontal cavity surface emitting semiconductor laser faces the patterned coating plate.

[0040] S32: Using an optical microscope, the light emitting area of ​​the horizontal cavity surface emitting semiconductor laser is aligned with the opening of the patterned coating plate, and the horizontal cavity surface emitting semiconductor laser, the patterned coating plate and the high temperature resistant magnet form a combination.

[0041] S33: Fix the assembly on a coating fixture by means of a high temperature resistant tape, and then place the coating fixture fixing the assembly into a coating machine to coat the light emitting area of ​​the horizontal cavity surface emitting semiconductor laser to form an anti-reflection film with a transmittance higher than 99.95%.

[0042] The high temperature resistant magnet is fixed on the coating fixture by means of the high temperature resistant tape. Since the horizontal cavity surface emitting semiconductor laser and the patterned coating plate are magnetically attracted to the high temperature resistant magnet, the horizontal cavity surface emitting semiconductor laser and the patterned coating plate are fixed on the coating fixture.

[0043] Figure 1The horizontal cavity surface emitting semiconductor laser based on the second-order grating structure shown in the figure emits light from the N side, that is, an anti-reflection film 9 is plated between the two N-side electrodes 8. The patterned anti-reflection film can avoid the N-type electrode 8 area, preventing the N-type electrode 8 from being covered with the anti-reflection film 9, and preventing the subsequent packaging process from being performed. Gold wire needs to be punched on the N-type electrode 8 for current injection, and then the whole is attached to the heat sink. If the N-type electrode 8 is covered with the anti-reflection film 9, the laser will not be able to be packaged and powered on. Similarly, the P-type electrode 7 cannot be covered with a high-reflection film 10, otherwise the P side of the laser cannot be attached to the heat sink.

[0044] For example, the size of the entire graphic coating plate is 10cm by 10cm, and the high temperature resistant magnet designed to correspond to the size of the graphic coating plate has a size of 100mm by 100mm by 5mm.

[0045] The present invention uses APS ion assistance during the anti-reflection film coating. Specifically, before the anti-reflection film coating, an electron gun is first used to fully pre-melt the high and low refractive index thin film materials. 2 and Ar as the working gas of the ion source, injecting O into the coating machine 2 ions and Ar ions, O 2 Ion implantation can improve the film stoichiometry, reduce oxygen loss, and obtain a film with lower absorption. Ar ion implantation increases the firmness of the film layer.

[0046] The present invention can also coat the side of the horizontal cavity surface emitting semiconductor laser opposite to the light emitting area to form a high reflective film with a reflectivity greater than 99.9%. Figure 1 The horizontal cavity surface emitting semiconductor laser based on the second-order grating structure shown has a high reflection film 10 plated between two P-type electrodes 7 .

[0047] The structure, stress, absorption coefficient and other parameters of the anti-reflection film and high-reflection film were obtained by Opti-layer cavity surface film design software simulation. In the film system design of the 980nm horizontal cavity surface emitting semiconductor laser based on the second-order grating structure, GaAs was selected as the substrate, and the film system structure of the anti-reflection film was 10nmAl 2 O 3 / 51.87nmTiO 2 / 101.54nmAl 2 O 3 , the film structure can meet the required transmittance greater than 99.95% at the central wavelength, such as Figure 5 The high-reflection film adopts a standard high-reflection film stacking structure. The peak at the center wavelength of the reflectivity curve is relatively wide. After multiple simulations and experimental verifications, a regular quarter-wavelength film structure is obtained. 11 pairs of Ta 2 O 5 / SiO2 Meet the design standards, reflectivity greater than 99.9%, such as Figure 6 shown.

[0048] In order to verify that the anti-reflection film coated on the light-emitting area can improve the output power, the performance of the horizontal cavity surface emitting semiconductor laser based on the second-order grating structure with the anti-reflection film coated on the light-emitting area and the light-emitting area without the anti-reflection film is compared. Figure 7 and Figure 8 As shown in the figure, the light-emitting areas of the two horizontal cavity surface emitting semiconductor lasers are the same, both of which are 336μm 200μm. The horizontal cavity surface emitting semiconductor laser without anti-reflection film on the light-emitting area has a maximum output power of 0.842W and a slope efficiency of 152mW / A at room temperature and continuous operation; the horizontal cavity surface emitting semiconductor laser without anti-reflection film on the light-emitting area has a maximum output power of 2.726W and a slope efficiency of 356mW / A at room temperature and continuous operation. Through performance comparison, it can be seen that after the light-emitting area is coated with a patterned anti-reflection film, the slope efficiency of the horizontal cavity surface emitting semiconductor laser is doubled and the output power is increased by more than three times. This proves that the anti-reflection film with a transmittance higher than 99.95% evaporated in the light-emitting area of ​​the N-side of the horizontal cavity surface emitting semiconductor laser can significantly improve the output efficiency and power density of the laser.

[0049] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0050] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for coating a patterned light outlet of a horizontal cavity surface emitting semiconductor laser, characterized in that: The steps include: S1: Draw the corresponding patterned coating plate layout according to the light emitting area structure of the horizontal cavity surface emitting semiconductor laser; S2: performing hole processing on the substrate according to the patterned coating plate pattern to form a patterned coating plate; S3: Align the light-emitting area structure of the horizontal-cavity surface emitting semiconductor laser with the patterned coating plate through a high-temperature resistant magnet, then fix the aligned horizontal-cavity surface emitting semiconductor laser and the patterned coating plate on a coating fixture, and then put the whole into a coating machine to coat the light-emitting area of ​​the horizontal-cavity surface emitting semiconductor laser to form a patterned anti-reflection film.

2. The method for coating a patterned light outlet of a horizontal cavity surface emitting semiconductor laser according to claim 1, characterized in that: In step S1, when the horizontal cavity surface emitting semiconductor laser adopts a photonic crystal structure, the patterned coating plate is designed as periodically arranged circular holes; when the horizontal cavity surface emitting semiconductor laser adopts a second-order grating structure, the patterned coating plate is designed as periodically arranged rectangular holes.

3. The method for coating a patterned light outlet of a horizontal cavity surface emitting semiconductor laser according to claim 1, characterized in that: In step S2, a laser cutting process or a laser etching process is used to perform hole opening processing on the substrate.

4. The method for coating a patterned light outlet of a horizontal cavity surface emitting semiconductor laser according to claim 1, characterized in that: In step S2, the substrate is a stainless steel sheet.

5. The method for coating a patterned light outlet of a horizontal cavity surface emitting semiconductor laser according to claim 1, characterized in that: Step S3 specifically includes the following steps: S31: magnetically fixing the horizontal cavity surface emitting semiconductor laser and the patterned coating plate on the same surface of the high temperature resistant magnet in sequence, with the light emitting area of ​​the horizontal cavity surface emitting semiconductor laser facing the patterned coating plate; S32: using an optical microscope to align the light emitting area of ​​the horizontal cavity surface emitting semiconductor laser with the opening of the patterned coating plate, so that the horizontal cavity surface emitting semiconductor laser, the patterned coating plate and the high temperature resistant magnet form a combination; S33: Fix the assembly on a coating fixture by means of a high temperature resistant tape, and then place the coating fixture fixing the assembly into a coating machine to coat the light emitting area of ​​the horizontal cavity surface emitting semiconductor laser to form an anti-reflection film with a transmittance higher than 99.95%.

6. The method for coating a patterned light outlet of a horizontal cavity surface emitting semiconductor laser according to claim 5, characterized in that: The film structure of the antireflection film with a transmittance greater than 99.95% is 10nmAl2O3 / 51.87nmTiO2 / 101.54nmAl2O3.

7. The method for coating a patterned light outlet of a horizontal cavity surface emitting semiconductor laser according to claim 1, characterized in that: Before coating, an electron gun is used to fully pre-melt the high and low refractive index thin film materials.

8. The method for coating a patterned light outlet of a horizontal cavity surface emitting semiconductor laser according to claim 1, characterized in that: During the coating process, O2 ions and Ar ions are injected into the coating machine.

9. The method for coating a patterned light outlet of a horizontal cavity surface emitting semiconductor laser according to claim 1, characterized in that: The horizontal cavity surface emitting semiconductor laser is coated on the side opposite to the light emitting area to form a high reflective film with a reflectivity greater than 99.9%.

10. The method for coating a patterned light outlet of a horizontal cavity surface emitting semiconductor laser according to claim 9, characterized in that: The film structure of the high-reflection film with a reflectivity greater than 99.9% is 11 pairs of quarter-wavelength Ta2O5 / SiO2.

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