A metamaterial energy transmission window based on sapphire substrate and preparation method thereof

Abstract

The present invention discloses a metamaterial energy transmission window based on a sapphire substrate and a preparation method thereof, which relates to the field of microwave electric vacuum technology, and a metal frame layer structure with grooves is arranged on a sapphire substrate window. Through the interaction between the metal structure and the electric field, a better transmission performance than the traditional box-type window is achieved; through the interaction between the rectangular metal frame and the electric field, the TM11 mode and the TE21 mode are stimulated on the sapphire substrate window, so that the energy transmission window achieves better mode matching, thereby reducing reflection, and can achieve better transmission performance than the traditional box-type window.

Description

Technical Field

[0001] The present invention relates to the field of microwave electric vacuum technology, and in particular to a sapphire substrate-based metamaterial energy transmission window and a preparation method thereof. Background Art

[0002] Microwave energy transmission windows have been developed along with the development of microwave technology in the field of high-power microwave vacuum electronic devices. Microwave energy transmission windows have two functions: to isolate the vacuum inside the tube from the external atmospheric environment; to feed out the signal inside the tube as losslessly as possible or to feed in the excitation outside the tube as losslessly as possible. The performance of the energy transmission window will directly affect the bandwidth, power, reliability and life of the corresponding device.

[0003] In the field of high power and high frequency, vacuum electronic devices, such as klystrons, traveling wave tubes, magnetrons, forward wave devices, etc., play a very important role in military and civilian applications such as radar, communications, electronic countermeasures, microwave heating, etc. Especially when the operating frequency reaches the millimeter wave, submillimeter wave and terahertz levels, vacuum electronic devices will be in an irreplaceable position. As an important component of vacuum electronic devices, the current common energy transmission window structures include box-type windows, ceramic step windows, and coaxial waveguide windows. Among them, the box-type window has the characteristics of large power tolerance, simple structure, simple and mature process manufacturing, and moderate wide bandwidth, but better transmission performance is still the research direction and focus of the energy transmission window. Summary of the invention

[0004] The technical problem to be solved by the present invention is that the transmission performance of the traditional metamaterial box-type window is still insufficient, especially when applied to the W band (75-110GHz), its transmission performance is still insufficient, which limits the reliability of high-power microwave vacuum electronic devices in this frequency band. The purpose of the present invention is to provide a metamaterial energy transmission window based on a sapphire substrate, which is structurally improved based on the existing metamaterial box-type window, and achieves better transmission performance through the interaction between the sapphire substrate with a metal frame structure and the electric field, thereby solving the above technical problems. In addition, the present invention also provides a method for preparing a metamaterial energy transmission window on a sapphire substrate.

[0005] The present invention is achieved through the following technical solutions:

[0006] The present invention provides a metamaterial energy transmission window based on a sapphire substrate, comprising a sapphire substrate with a rectangular metal frame, for allowing a rectangular waveguide and a circular waveguide to pass through;

[0007] The rectangular metal frame is arranged on the bottom surface of the sapphire substrate;

[0008] When the waveform is propagating, the central axes of the rectangular waveguide and the circular waveguide overlap, and the central axes are perpendicular to the sapphire substrate; the projection of the circular waveguide on the sapphire substrate covers the projection of the rectangular metal frame on the sapphire substrate.

[0009] Working principle of this scheme: The transmission performance of the traditional metamaterial box-shaped window is still insufficient, especially when applied to the W band (75-110GHz), its transmission performance is still insufficient, which limits the reliability of high-power microwave vacuum electronic devices in this frequency band. This scheme provides a metamaterial energy transmission window based on a sapphire substrate. Based on the structural improvement of the existing metamaterial box-shaped window, the interaction between the sapphire substrate with a metal frame structure and the electric field is used to achieve better transmission performance and solve the transmission performance problem. This structure can be used in vacuum electronic devices to isolate the atmosphere and the vacuum environment in the tube, and achieve good microwave input and output performance.

[0010] A rectangular metal frame is arranged on the surface of the sapphire substrate window on the input side of the energy transmission window. Through the interaction between the rectangular metal frame and the electric field, the TM11 mode and the TE21 mode are stimulated on the sapphire substrate window, so that the energy transmission window achieves better mode matching, thereby reducing reflection and achieving better transmission performance than the traditional box-type window.

[0011] A further optimization scheme is that the sapphire substrate is a circular substrate, and the diameter of the circular substrate is larger than the diameter of the circular waveguide;

[0012] The circumscribed circle of the rectangular waveguide coincides with the cross section of the circular waveguide. The diameter length of the circular waveguide is equal to the diagonal length of the rectangular waveguide, and the diameter of the sapphire circular window is slightly larger than the diameter of the circular waveguide.

[0013] A further optimization solution is that the length of the rectangular waveguide is 2.54 mm and the width is 1.27 mm, and the diameter of the circular waveguide is 2.84 mm-2.9 mm.

[0014] A further optimization scheme is that both long sides of the rectangular metal frame are arranged with a plurality of grooves with different structures;

[0015] The grooves located on the same side of the metal frame are symmetrical about a first center line parallel to the width direction of the metal frame, and the depths of the plurality of grooves located on one side of the first center line are different;

[0016] The grooves arranged at two long sides of the metal frame are symmetrical about a second center line parallel to the length direction of the metal frame.

[0017] A further optimization scheme is that 2N rectangular grooves are evenly arranged on each long side of the rectangular metal frame, the widths of all the rectangular grooves are equal, and the depths of the rectangular grooves first increase and then decrease.

[0018] A further optimization scheme is that the thickness d of the sapphire substrate is 0.1mm-0.12mm, the radius r is 1.42mm-1.63mm, and the axial dielectric constant ε=9.6; the width W of the rectangular metal frame is 1.2mm-1.8mm, and the length is 1.67mm-2.12mm; the cross-sectional width w of the rectangular metal frame is 0.01mm-0.07mm, and the thickness h is 0.0005mm-0.015mm.

[0019] A further optimization scheme is that 6 rectangular grooves are evenly arranged on each long side of the rectangular metal frame, the spacing between each rectangular groove is 0.275mm-0.33mm, the width t of the rectangular groove is 0.055mm-0.155mm, and the depths of the rectangular grooves are: g1 is 0.03mm-0.12mm, g2 is 0.03mm-0.12mm, g3 is 0.03mm-0.16mm, g4 is 0.03mm-0.16mm, g5 is 0.03mm-0.12mm, and g6 is 0.03mm-0.12mm.

[0020] A further optimization scheme is that it also includes an upper window frame, a support ring and a lower window frame welded in sequence; the sapphire substrate with a metal frame structure is installed in the support ring, and the upper window frame and the lower window frame form a synchronous rectangular waveguide and a circular waveguide.

[0021] The present invention also provides a method for manufacturing a metamaterial energy transmission window based on a sapphire substrate, which is used to prepare the metamaterial energy transmission window described in the above-mentioned scheme. The metamaterial energy transmission window of the sapphire substrate includes a non-metallic region and a metal region, and the metal region includes: a rectangular metal frame portion and a welding portion;

[0022] Includes steps:

[0023] S1. Protecting non-metallic areas based on photoresist masks;

[0024] S2, preparing the metal region based on the magnetron sputtering method;

[0025] S3. After the metal area is prepared, the photoresist mask is removed using a stripping solution.

[0026] A further optimization scheme is that S1 includes the following sub-steps:

[0027] S11, coating the polyimide film using a KW-4A type coating machine and baking at 240°C for 100 min;

[0028] S12, preparing an etching solution to etch a silicon wafer to obtain a mask structure required for X-ray lithography;

[0029] S13, coating methyl methacrylate photoresist at corresponding positions of the silicon wafer with a coating thickness of 100 μm, and baking the silicon wafer at 140° C. for 90 minutes after coating;

[0030] S14, based on 1B3 beamline synchrotron radiation X-ray lithography, with an exposure dose of 300 mA / h and development for 10 min, to obtain a methyl methacrylate mask structure of a desired size;

[0031] S15, soaking the silicon wafer in a weak alkaline solution for 20 minutes to ensure that the methyl methacrylate mask is separated from the silicon wafer;

[0032] S16. Use methyl methacrylate glue to bond the methyl methacrylate mask to the sapphire substrate.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] The present invention provides a metamaterial energy transmission window based on a sapphire substrate and a preparation method thereof, wherein a metal frame layer structure with grooves is arranged on a sapphire substrate window. Through the interaction between the metal structure and the electric field, a better transmission performance than the traditional box-type window is achieved; through the interaction between the rectangular metal frame and the electric field, the TM11 mode and the TE21 mode are stimulated on the sapphire substrate window, so that the energy transmission window achieves better mode matching, thereby reducing reflection and achieving a better transmission performance than the traditional box-type window. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0036] Figure 1 Schematic diagram of the structure of the metamaterial energy transfer window based on sapphire substrate;

[0037] Figure 2 This is a schematic diagram of the structure of a simulation model of a metamaterial energy transfer window based on a sapphire substrate;

[0038] Figure 3 Schematic diagram of the sapphire substrate structure with a metal frame structure;

[0039] Figure 4 This is a schematic diagram of the left side of the upper window frame;

[0040] Figure 5 This is a schematic diagram of the right side of the upper window frame;

[0041] Figure 6 is a schematic diagram of the cross section of the upper window frame;

[0042] Figure 7 This is a schematic diagram of the left side of the lower window frame;

[0043] Figure 8 This is a schematic diagram of the right side of the lower window frame;

[0044] Fig. 9 is a schematic diagram of the cross section of the lower window frame;

[0045] Fig.10 It is a partially enlarged schematic diagram of a rectangular metal frame;

[0046] Fig.11 This is a front view of the support ring structure;

[0047] Fig.12 It is a schematic diagram of the back side of the support ring structure;

[0048] Fig.13 It is a top view of the support ring structure;

[0049] Fig.14 It is a side schematic diagram of the support ring structure;

[0050] Fig.15 This is a comparison chart of the simulated reflection coefficients of the metamaterial energy transfer window and the traditional box-type window;

[0051] Fig.16 This is a comparison chart of the simulated transmission coefficients of the metamaterial energy transfer window and the traditional box-type window;

[0052] Fig.17 This is a comparison chart of the simulated standing wave coefficients of the metamaterial energy transfer window and the traditional box-type window.

[0053] Marks and corresponding parts names in the attached drawings:

[0054] 1- rectangular waveguide, 2- circular waveguide, 3- sapphire substrate, 4- metal frame structure, 5- upper window frame, 6- support ring, 7- lower window frame. DETAILED DESCRIPTION

[0055] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary implementation modes of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0056] Example 1

[0057] This embodiment provides a metamaterial energy transmission window based on a sapphire substrate, such as Figure 1 and Figure 2As shown, it includes: a rectangular waveguide, a circular waveguide and a sapphire substrate with a metal frame structure;

[0058] like Figure 3 As shown, the sapphire substrate is a circular substrate, the metal frame structure is a rectangular metal frame, the rectangular metal frame is arranged on the bottom surface of the circular substrate, and the center of the rectangular metal frame coincides with the center point O of the circular substrate;

[0059] Both the rectangular waveguide and the circular waveguide vertically pass through the sapphire substrate with point O as the center, and the projection of the circular waveguide on the circular substrate covers the projection of the rectangular metal frame on the circular substrate.

[0060] The diameter of the circular substrate is larger than the diameter of the circular waveguide;

[0061] The circumscribed circle of the rectangular waveguide coincides with the cross section of the circular waveguide.

[0062] In this embodiment, the wide side length a=2.54, and the narrow side length b=1.27.

[0063] Both long sides of the rectangular metal frame are arranged with a plurality of grooves with different structures;

[0064] The grooves located on the same side of the metal frame are symmetrical about a first center line parallel to the width direction of the metal frame, and the depths of the plurality of grooves located on one side of the first center line are different;

[0065] The grooves arranged at two long sides of the metal frame are symmetrical about a second center line parallel to the length direction of the metal frame.

[0066] 2N rectangular grooves are evenly arranged on each long side of the rectangular metal frame, the widths of all the rectangular grooves are equal, and the depths of the rectangular grooves increase first and then decrease.

[0067] The thickness d of the sapphire substrate is 0.1mm-0.12mm, the radius r is 1.42mm-1.63mm, and the axial dielectric constant ε is 9.6; the width W of the rectangular metal frame is 1.2mm-1.8mm, and the length is 1.67mm-2.12mm; the cross-sectional width w of the rectangular metal frame is 0.01mm-0.07mm, and the thickness h is 0.0005mm-0.015mm; in this embodiment, the thickness d of the sapphire substrate is 0.12mm, the radius c_r is 1.56mm, the width W of the rectangular metal frame is 1.27mm, and the length L is 1.856mm; the cross-sectional width of the rectangular metal frame is w=0.01mm, and the thickness h=0.006mm.

[0068] Each long side of the rectangular metal frame is evenly arranged with 6 rectangular grooves, the spacing between each rectangular groove is 0.275mm-0.33mm, the width t of the rectangular groove is 0.055mm-0.155mm, and the depth of the rectangular groove is: g1 is 0.03mm-0.12mm, g2 is 0.03mm-0.12mm, g3 is 0.03mm-0.16mm, g4 is 0.03mm-0.16mm, g5 is 0.03mm-0.12mm, and g6 is 0.03mm-0.12mm. In this embodiment, the width t of the rectangular groove is 0.115mm, and the depth of the rectangular groove is: g1=0.1mm, g2=0.09mm, g3=0.14mm, g4=0.14mm, g5=0.09mm, and g6=0.1mm.

[0069] Example 2

[0070] Based on the previous embodiment, this embodiment also includes an upper window frame, a support ring and a lower window frame welded in sequence; the sapphire substrate with a metal frame structure is installed in the support ring, and the upper window frame and the lower window frame form a synchronous rectangular waveguide and a circular waveguide.

[0071] The structure of the upper window frame is as follows Figure 4-Figure 6 As shown, the specific parameters are as follows (unit: mm):

[0072] The length of the wide side of the rectangular waveguide is a = 2.54 mm, the length of the narrow side of the rectangular waveguide is b = 1.27 mm, the diameter of the lower chassis of the upper window frame is s_r1 = 20 mm, the diameter of the test mold insertion slot is s_r2 = 6 mm, the diameter of the upper window frame support ring fixing platform is s_r3 = 10 mm, the inner diameter of the upper window frame circular waveguide is s_r4 = 2.84 mm, the outer diameter of the upper window frame circular waveguide is s_r5 = 2.84 mm, the height of the lower chassis of the upper window frame is s_d1 = 0.5 mm, and the test mold fixing slot edge is Center distance s_d2=3.5mm, test mold fixed groove width s_d3=1mm, upper window frame support ring fixed groove width s_d4=1mm, upper window frame support ring fixed groove edge and center distance s_d5=3.5mm, upper window frame support ring fixed platform height s_l1=4.3mm, upper window frame upper waveguide length s_l2=1.84mm, upper window frame support ring fixed groove depth s_l3=2.4mm, upper window frame circular waveguide length s_l4=0.45mm.

[0073] The structure diagram of the lower window frame is as follows Figure 7-Figure 9As shown, the specific parameters are: the length of the wide side of the rectangular waveguide a = 2.54, the length of the narrow side of the rectangular waveguide b = 1.27mm, the diameter of the lower chassis of the lower window frame x_r1 = 19.05mm, the diameter of the lower window frame support ring fixing platform x_r2 = 10mm, the outer diameter of the lower window frame window waveguide x_r3 = 3.82mm, the inner diameter of the lower window frame window waveguide x_r4 = 3.12mm, and the diameter of the lower window frame circular waveguide x_r5 = 2.84 mm, upper window frame support ring fixing groove width x_d1=1, lower window frame support ring fixing groove edge and center distance x_d2=3.5mm, lower window frame circular waveguide length x_d3=0.45mm, lower window frame window sheet waveguide length x_d4=0.62mm, lower window frame lower chassis height x_l1=4mm, lower window frame support ring fixing platform height x_l2=2.4mm, lower window frame upper waveguide length x_l3=2.07mm.

[0074] The sapphire substrate structure with a metal frame structure is shown in the figure Fig.10 As shown, the substrate is sapphire, and its axial dielectric constant ε = 9.6. A rectangular metal frame structure with grooves is plated on one side of the sapphire substrate. There are 6 grooves on each of the two long sides of the rectangular metal frame structure, and the metal frame structure is symmetrical along the dotted line. The specific parameters are: sapphire substrate window diameter c_r = 3.12mm, sapphire substrate window thickness d = 0.12mm, rectangular metal frame height W = 1.27mm, metal strip width w = 0.01mm constituting the height of the rectangular metal frame, rectangular metal frame thickness h = 0.006mm, rectangular groove period p = 0.306mm, rectangular groove width t = 0.115mm, rectangular groove depths g1 = 0.1mm, g2 = 0.09mm and g3 = 0.04mm respectively.

[0075] The structural diagram of the support ring is as follows: Figure 11-Figure 14 As shown, the specific parameters are: total height of support ring z_l1 = 8.21mm, length of support ring buckle z_l2 = 8mm, height of support ring observation hole from bottom z_l3 = 4.28mm, distance between support ring buckle edge and center z_l4 = 3.5mm, diameter of support ring observation hole z_r1 = 4mm, inner diameter of support ring z_r2 = 10mm, outer diameter of support ring z_r3 = 10.8mm.

[0076] Example 3

[0077] The present embodiment provides a method for manufacturing a metamaterial energy transmission window based on a sapphire substrate, which is used to prepare the metamaterial energy transmission window of Example 1 or Example 2. The metamaterial energy transmission window of the sapphire substrate includes a non-metallic area and a metal area, and the metal area includes: a rectangular metal frame part and a welding part; wherein the metal frame structure part is copper, the welding part is copper and titanium, and the welding part area is the part where the radius of the window exceeds the radius of the circular waveguide.

[0078] Includes steps:

[0079] S1. Protecting non-metallic areas based on photoresist masks;

[0080] S2, preparing the metal region based on the magnetron sputtering method;

[0081] S3. After the metal area is prepared, the photoresist mask is removed using a stripping solution.

[0082] S1 includes the following sub-steps:

[0083] S11, coating the polyimide film using a KW-4A type coating machine and baking at 240°C for 100 min;

[0084] S12, preparing an etching solution to etch a silicon wafer to obtain a mask structure required for X-ray lithography; the volume ratio of the etching solution components is hydrofluoric acid: nitric acid: glacial acetic acid: purified water = 3:1:2:2, and the etching time is 50 minutes;

[0085] S13, coating methyl methacrylate photoresist at corresponding positions of the silicon wafer with a coating thickness of 100 μm, and baking the silicon wafer at 140° C. for 90 minutes after coating;

[0086] S14, based on 1B3 beamline synchrotron radiation X-ray lithography, with an exposure dose of 300 mA / h and development for 10 min, to obtain a methyl methacrylate mask structure of a desired size;

[0087] S15, soaking the silicon wafer in a weak alkaline solution for 20 minutes to ensure that the methyl methacrylate mask is separated from the silicon wafer;

[0088] S16. Use methyl methacrylate glue to bond the methyl methacrylate mask to the sapphire substrate.

[0089] Example 4

[0090] This embodiment uses three-dimensional electromagnetic simulation software to simulate and calculate the transmission performance of the metamaterial energy transmission window based on the sapphire substrate in the above embodiment. Fig.15 , Fig.16 and Fig.17 The simulation model calculation results under the above dimensions. In the simulation process, the conductivity of the waveguide is set to 2x10 7S / m. The given metamaterial energy transmission window size is mainly used in the W band (75-110GHz). In order to ensure the convergence of the calculation and improve the calculation accuracy, the simulation frequency range is adjusted to 70-115GHz. The model has an S11 better than -22.5dB, an S21 better than -0.2dB, and a VSWR better than 1.17 within a bandwidth of 35GHz within 75-110GHz. The simulation results show that the metamaterial energy transmission window provided by the present invention can obtain good transmission performance.

[0091] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A metamaterial energy transmission window based on a sapphire substrate, characterized in that: It comprises a sapphire substrate (3) with a rectangular metal frame (4), which is used for the rectangular waveguide (1) and the circular waveguide (2) to pass through; the rectangular metal frame (4) is arranged on the bottom surface of the sapphire substrate (3); When the waveform is propagating, the central axes of the rectangular waveguide (1) and the circular waveguide (2) overlap, and the central axes are perpendicular to the sapphire substrate (3); the projection of the circular waveguide (2) on the sapphire substrate covers the projection of the rectangular metal frame (4) on the sapphire substrate; Both long sides of the rectangular metal frame (4) are arranged with a plurality of grooves; The grooves located on the same side of the metal frame are symmetrical about a first center line parallel to the width direction of the metal frame, and the depths of the plurality of grooves located on one side of the first center line are different; The grooves arranged on the two long sides of the metal frame are symmetrical about a second center line parallel to the length direction of the metal frame; 2N rectangular grooves are evenly arranged on each long side of the rectangular metal frame (4), the widths of all the rectangular grooves are equal, and the depths of the rectangular grooves first increase and then decrease, wherein N≥3.

2. The sapphire-based metamaterial energy transmission window according to claim 1, characterized in that: The sapphire substrate (3) is a circular substrate, and the diameter of the circular substrate is greater than the diameter of the circular waveguide (2); The circumscribed circle of the rectangular waveguide (1) coincides with the cross section of the circular waveguide (2).

3. The sapphire-based metamaterial energy transmission window according to claim 1, characterized in that: The rectangular waveguide (1) has a length of 2.54 mm and a width of 1.27 mm, and the circular waveguide (2) has a diameter of 1.42 mm-1.45 mm.

4. The sapphire-based metamaterial energy transmission window according to claim 1, characterized in that: The sapphire substrate (3) has a thickness d of 0.1 mm to 0.12 mm, a radius r of 1.42 mm to 1.63 mm, and an axial dielectric constant ε of 9.6; a rectangular metal frame has a width W of 1.2 mm to 1.8 mm, and a length L of 1.67 mm to 2.12 mm; a cross-sectional width w of the rectangular metal frame of 0.01 mm to 0.07 mm, and a thickness h of 0.0005 mm to 0.015 mm.

5. The sapphire-based metamaterial energy transmission window according to claim 4, characterized in that: Each long side of the rectangular metal frame (4) is evenly arranged with 6 rectangular grooves, the spacing between the rectangular grooves is 0.275mm-0.33mm, the width t of the rectangular grooves is 0.055mm-0.155mm, and the depths of the rectangular grooves are as follows: g1 is 0.03mm-0.12mm, g2 is 0.03mm-0.12mm, g3 is 0.03mm-0.16mm, g4 is 0.03mm-0.16mm, g5 is 0.03mm-0.12mm, and g6 is 0.03mm-0.12mm.

6. The sapphire-based metamaterial energy transmission window according to claim 1, characterized in that: It also comprises an upper window frame (5), a support ring (6) and a lower window frame (7) which are welded in sequence; the sapphire substrate (3) is mounted in the support ring (6), and the upper window frame (5) and the lower window frame (7) form a synchronous rectangular waveguide (1) and a circular waveguide (2).

7. A method for manufacturing a metamaterial energy transmission window based on a sapphire substrate, used to prepare the metamaterial energy transmission window according to any one of claims 1 to 6, characterized in that: The metamaterial energy transmission window includes a non-metallic area and a metal area, and the metal area includes: a rectangular metal frame part and a welding part; Includes steps: S1. Protecting non-metallic areas based on photoresist masks; S2, preparing the metal region based on the magnetron sputtering method; S3. After the metal area is prepared, the photoresist mask is removed using a stripping solution.

8. The method for manufacturing a sapphire-based metamaterial energy transmission window according to claim 7, characterized in that: S1 includes the following sub-steps: S11, coating a polyimide film using a KW-4A type coating machine, and baking at a temperature of 240° C. for 100 min; S12, preparing an etching solution to etch a silicon wafer to obtain a mask structure required for X-ray lithography; S13, coating methyl methacrylate photoresist at corresponding positions of the silicon wafer with a coating thickness of 100 μm, and baking the silicon wafer at 140° C. for 90 min after coating; S14, based on 1B3 beamline synchrotron radiation X-ray lithography, with an exposure dose of 300 mA / h and development for 10 min, to obtain a methyl methacrylate mask structure of a desired size; S15, soaking the silicon wafer in a weak alkaline solution for 20 minutes to ensure that the methyl methacrylate mask is separated from the silicon wafer; S16. Use methyl methacrylate glue to bond the methyl methacrylate mask to the sapphire substrate.

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