High power polarization maintaining mirror and optical apparatus, test system, film system design method

Abstract

This application discloses a high-power polarization-maintaining mirror, optical equipment, testing system, and film system design method, relating to the field of optical device technology. The high-power polarization-maintaining mirror includes a first film layer, a second film layer, and a substrate sequentially arranged along the incident light direction, with a high power range of 1.61 J / cm². 2 Up to 1.81 J / cm 2 The first film layer is formed by depositing a low-refractive-index material, and the second film layer is formed by alternating deposition of a high-refractive-index material and the low-refractive-index material. The refractive index of the low-refractive-index material ranges from 1.3 to 1.5, and the refractive index of the high-refractive-index material ranges from 1.8 to 2.3. The extinction coefficients of both the low-refractive-index material and the high-refractive-index material are less than 10. ‑4 The high-power polarization-maintaining mirror of this application has low absorption and high reflectivity, which can effectively maintain the stability of the polarization state of the incident light.

Description

Technical Field

[0001] This application relates to the field of optical device technology, and in particular to a high-power polarization-maintaining mirror and optical equipment, testing system, and film system design method. Background Technology

[0002] In laser applications, especially in high-power laser environments, achieving efficient and stable transmission and control of laser beams is a core challenge. As a key component of the optical path, the performance of the reflector directly determines the power limit and stability of the entire laser system. However, when ordinary mirrors in related technologies are used at an angle, a large phase difference will appear between S-polarized light and P-polarized light, changing the polarization state of the incident light. Summary of the Invention

[0003] In view of the above-mentioned defects or deficiencies in the related technologies, it is desirable to provide a high-power polarization-maintaining mirror and optical equipment, testing system, and film system design method, which have high reflectivity and high polarization-maintaining performance.

[0004] In a first aspect, this application provides a high-power polarization-maintaining mirror, which includes a first film layer, a second film layer, and a substrate arranged sequentially along the incident light direction, and the high power range is 1.61 J / cm². 2 Up to 1.81 J / cm 2 ; The first film layer is formed by depositing a low-refractive-index material, and the second film layer is formed by alternating deposition of a high-refractive-index material and the low-refractive-index material. The refractive index of the low-refractive-index material ranges from 1.3 to 1.5, and the refractive index of the high-refractive-index material ranges from 1.8 to 2.3. The extinction coefficients of both the low-refractive-index material and the high-refractive-index material are less than 10. -4 .

[0005] Optionally, in some embodiments of this application, the low refractive index material is SiO2, and the high refractive index material is HfO2.

[0006] Optionally, in some embodiments of this application, the thickness of the low-refractive-index material of the first film layer is 2.228 times the wavelength of one-quarter incident light, the thickness of the high-refractive-index material of the second film layer is 1.117 times the wavelength of one-quarter incident light, the thickness of the low-refractive-index material of the second film layer is 1.114 times the wavelength of one-quarter incident light, and the alternation period of the high-refractive-index material and the low-refractive-index material in the second film layer is 14 sets.

[0007] Optionally, in some embodiments of this application, the substrate is a Si substrate, a SiO2 substrate, a Ge substrate, or a sapphire substrate.

[0008] Optionally, in some embodiments of this application, the wavelength range of the incident light is 400 nm to 1700 nm, and the incident angle is 45 degrees.

[0009] In a second aspect, this application provides an optical device, which includes a high-power polarization-maintaining mirror as described in any one of the first aspects.

[0010] Thirdly, this application provides a testing system for polarization maintaining test of the high-power polarization maintaining mirror according to any one of the first aspects. The testing system includes a laser, a GranTeller prism, a half-wave plate, the high-power polarization maintaining mirror, and a polarization measuring instrument arranged in sequence. The Glan Taylor prism is used to convert the incident light generated by the laser into linearly polarized light; the half-wave plate is used to adjust the azimuth angle of the linearly polarized light; and the polarization measuring instrument is used to receive the reflected light and detect the polarization parameters of the high-power polarization-maintaining mirror.

[0011] Optionally, in some embodiments of this application, the polarization measuring instrument is specifically used to collect a first ellipsoid when the high-power polarization-maintaining mirror is not placed in the optical path, collect a second ellipsoid when the high-power polarization-maintaining mirror is placed in the optical path, and calculate the difference between the second ellipsoid and the first ellipsoid.

[0012] Fourthly, this application provides a film system design method, which is used for the film system design of the high-power polarization-maintaining mirror according to any one of the first aspects, the film system design method comprising: An initial film structure is constructed, and high-refractive-index and low-refractive-index materials are selected, along with the wavelength and angle of incidence of the incident light. The initial film structure is Air / k1L (k2H k3L)^m / Sub, where Air represents air, Sub represents the substrate, L represents the optical thickness of the low-refractive-index material at one-quarter of the incident light wavelength, H represents the optical thickness of the high-refractive-index material at one-quarter of the incident light wavelength, k1, k2, and k3 represent the coefficients of each one-quarter incident light wavelength optical thickness, and m represents the number of layers, ranging from 10 to 100. The initial film structure was simulated and iteratively optimized, and the polarization parameters of the high-power polarization-maintaining mirror prepared by the actual coating process were continuously detected until the phase difference between S-polarized light and P-polarized light in the polarization parameters of the high-power polarization-maintaining mirror was 0, and the measured average reflectivity was greater than 99%.

[0013] As can be seen from the above technical solutions, the embodiments of this application have the following advantages: This application provides a high-power polarization-maintaining mirror and optical device, a testing system, and a film system design method. The high-power polarization-maintaining mirror includes a first film layer, a second film layer, and a substrate sequentially arranged along the incident light direction, and has a high power range of 1.61 J / cm². 2 Up to 1.81 J / cm 2 The first film layer is formed by depositing a low-refractive-index material, and the second film layer is formed by alternating deposition of high-refractive-index and low-refractive-index materials. The refractive index of the low-refractive-index material ranges from 1.3 to 1.5, and the refractive index of the high-refractive-index material ranges from 1.8 to 2.3. The extinction coefficients of both the low-refractive-index and high-refractive-index materials are less than 10. -4 It has low absorption and high reflectivity. Test results show that when the azimuth angle of the incident linearly polarized light is in the range of -90 degrees to 90 degrees, the ellipticity difference that can characterize the polarization characteristics is within ±0.3 degrees, corresponding to an extinction ratio of more than 36476:1, which can effectively maintain the stability of the polarization state of the incident light. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the structure of a high-power polarization-maintaining reflector provided in an embodiment of this application; Figure 2 A design reflection spectrum of S-polarized light and P-polarized light is provided for embodiments of this application; Figure 3 A measured reflectance spectrum of S-polarized light and P-polarized light is provided for an embodiment of this application; Figure 4 A structural block diagram of an optical device provided in an embodiment of this application; Figure 5 This is a schematic diagram of the optical path of a testing system provided in an embodiment of this application; Figure 6 This application provides an embodiment of a high-power polarization-maintaining mirror with ellipticity difference curves under different incident ray polarization azimuth angles. Figure 7 A schematic flowchart illustrating a membrane system design method provided in an embodiment of this application; Figure 8 This is a flowchart illustrating a specific example of a membrane system design method provided in an embodiment of this application.

[0016] Figure label: 10-High-power polarization-maintaining mirror, 101-First film layer, 102-Second film layer, 103-Substrate, 20-Optical equipment, 30-Test system, 301-Laser, 302-Glan Taylor prism, 303-Half-wave plate, 304-Polarization measuring instrument. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The following examples illustrate this. Figures 1 to 8 This application provides a detailed description of the high-power polarization-maintaining mirror and optical equipment, testing system, and film design method provided in the embodiments of this application.

[0020] Please refer to Figure 1 This is a schematic diagram of a high-power polarization-maintaining mirror provided in an embodiment of this application. The high-power polarization-maintaining mirror 10 includes a first film layer 101, a second film layer 102, and a substrate 103 arranged sequentially along the incident light direction. The high power range is 1.61 J / cm². 2 Up to 1.81 J / cm 2 The incident light has a wavelength range of 400 nm to 1700 nm and an incident angle of 45 degrees. The first film layer 101 is formed by deposition of a low-refractive-index material, and the second film layer 102 is formed by alternating deposition of high-refractive-index and low-refractive-index materials. The refractive index of the low-refractive-index material ranges from 1.3 to 1.5, and the refractive index of the high-refractive-index material ranges from 1.8 to 2.3. The extinction coefficients of both the low-refractive-index and high-refractive-index materials are less than 10. -4 .

[0021] In some embodiments of this application, the low-refractive-index material can be SiO2 or MgF2, etc., and the high-refractive-index material can be HfO2, TiO2, or ZrO2, etc. Further, taking SiO2 as the low-refractive-index material and HfO2 as the high-refractive-index material as an example, SiO2 has the characteristics of low dispersion, low extinction coefficient, and low absorption at the incident wavelength, while HfO2, in addition to low absorption, also has the advantage of a high laser damage threshold, making it particularly suitable for high-power laser environments. Both SiO2 and HfO2 are selected as dielectric materials for controlling the polarization state of the reflector. Since HfO2 is prone to sputtering during evaporation, this embodiment uses a method of evaporating hafnium metal, which is less prone to sputtering, in an oxygen environment, thus ensuring the good performance of HfO2 while avoiding the sputtering disadvantage. The optimized film structure is Air / 2.228L (1.117H 1.114L)^14 / Sub, where Air represents air, Sub represents the substrate, L represents the optical thickness of the low-refractive-index material at one-quarter of the incident light wavelength, and H represents the optical thickness of the high-refractive-index material at one-quarter of the incident light wavelength. Specifically, the thickness of the low-refractive-index material in the first film layer 101 is 2.228 times the one-quarter incident light wavelength, the thickness of the high-refractive-index material in the second film layer 102 is 1.117 times the one-quarter incident light wavelength, and the thickness of the low-refractive-index material in the second film layer 102 is 1.114 times the one-quarter incident light wavelength. The alternation period between the high-refractive-index and low-refractive-index materials in the second film layer 102 is 14 sets, and the incident light wavelength is 808 nm. Furthermore, the substrate 103 can be a Si substrate, SiO2 substrate, Ge substrate, or sapphire substrate, etc. After optimization, the film system of the high-power polarization-maintaining mirror 10 can achieve high reflectivity for both S-polarized and P-polarized light at an incident wavelength of 808 nm and an incident angle of 45 degrees, while ensuring that the phase difference between the two reflections is 0, thus meeting the polarization-maintaining requirement. The designed reflection spectra of S-polarized and P-polarized light are as follows: Figure 2 As shown, Figure 2 The Rs curve corresponds to the design reflection spectrum of S-polarized light, and the Rp curve corresponds to the design reflection spectrum of P-polarized light.

[0022] In actual fabrication, for example, an ion-assisted electron beam evaporation method can be used to sequentially deposit a second film layer 102 and a first film layer 101 on a substrate 103. Subsequently, the spectrum of the high-power polarization-maintaining mirror 10 is measured using a spectrophotometer. The measured reflectance spectra of S-polarized light and P-polarized light at a 45-degree incident angle are as follows: Figure 3 As shown, Figure 3 The R's curve corresponds to the measured reflectance spectrum of S-polarized light, and the R'p curve corresponds to the measured reflectance spectrum of P-polarized light. As shown in the figure, at a wavelength of 808 nm, the measured reflectance of S-polarized light is 99.36%, and the measured reflectance of P-polarized light is 98.82%, with an average reflectance of 99.09%.

[0023] In another aspect, this application provides an optical device. Please refer to... Figure 4 This is a structural block diagram of an optical device provided in an embodiment of this application. The optical device 20 includes... Figures 1 to 3 In any of the corresponding embodiments, the high-power polarization-maintaining reflector 10 can maintain polarization regardless of whether linearly polarized light, circularly polarized light, or elliptically polarized light is incident.

[0024] In another aspect, embodiments of this application provide a testing system, the testing system 30 being used for Figures 1 to 3 The polarization-maintaining test of any of the high-power polarization-maintaining mirrors 10 in the corresponding embodiments. Please refer to... Figure 5 This is a schematic diagram of the optical path of a test system provided in an embodiment of this application. The test system 30 includes a laser 301, a Glan Taylor prism 302, a half-wave plate 303, a high-power polarization-maintaining mirror 10, and a polarization measuring instrument 304 arranged in sequence. The Glan Taylor prism 302 can convert the incident light generated by the laser 301 into linearly polarized light, the half-wave plate 303 can adjust the azimuth angle of the linearly polarized light, and the polarization measuring instrument 304 can receive the reflected light and detect the polarization parameters of the high-power polarization-maintaining mirror 10.

[0025] Using 808nm linearly polarized light as the incident light, the polarization measuring instrument 304 first collects the first ellipsometric reading when the high-power polarization-maintaining mirror 10 is not placed in the optical path. Then, with the high-power polarization-maintaining mirror 10 placed in the optical path, and the linearly polarized light adjusted by the half-wave plate 303 incident at a 45-degree angle, the second ellipsometric reading is collected, and the difference between the second and first ellipsometric readings is calculated. The smaller the difference, the smaller the change in polarization state of the incident light after reflection by the high-power polarization-maintaining mirror 10, and the better the polarization-maintaining performance of the high-power polarization-maintaining mirror 10. Furthermore, the angle of the half-wave plate 303 is rotated from 0 to 90 degrees, and the first and second ellipsometric readings are collected again every 5 degrees, and the difference between the two is calculated. Since rotating the half-wave plate 303 by 5 degrees can rotate the azimuth angle of linearly polarized light by approximately 10 degrees, it is possible to test the polarization-maintaining performance of the high-power polarization-maintaining mirror 10 under different incident linearly polarized light azimuth angles. The results are as follows: Figure 6 As shown in the figure. Test data indicates that when the azimuth angle of the incident polarized light is within the range of -90 degrees to 90 degrees, the ellipticity difference, which characterizes the polarization properties, is within ±0.3 degrees, corresponding to an extinction ratio of over 36476:1, effectively maintaining the stability of the polarization state of the incident light. Furthermore, after standard laser damage threshold testing under the conditions of wavelength 532 nm, pulse width 5 ns, and repetition frequency 10 Hz, the damage threshold of the high-power polarization-maintaining mirror 10 reaches 1.71 J / cm². 2This verifies the high laser damage resistance achieved by the high-power polarization-maintaining mirror 10 under the HfO2 / SiO2 material system and optimized film structure.

[0026] In another aspect, embodiments of this application provide a membrane system design method, which is used for... Figures 1 to 3 The corresponding embodiment describes the film system design of any of the high-power polarization-maintaining mirrors 10. Please refer to... Figure 7 This is a flowchart illustrating a membrane system design method provided in an embodiment of this application. The membrane system design method specifically includes the following steps: S101, construct the initial film structure, and select high-refractive-index and low-refractive-index materials, as well as set the wavelength and incident angle of the incident light.

[0027] For example, combined Figure 8 As shown in the process flow, the initial film structure can be Air / k1L (k2H k3L)^m / Sub, where Air represents air, Sub represents the substrate, L represents the optical thickness of the low-refractive-index material at one-quarter incident wavelength, H represents the optical thickness of the high-refractive-index material at one-quarter incident wavelength, k1, k2 and k3 represent the coefficients of each one-quarter incident wavelength optical thickness, the incident wavelength is 808nm, the incident angle is 45 degrees, and m represents the number of layers, ranging from 10 to 100.

[0028] S102, the initial film structure is simulated and iteratively optimized, and the polarization parameters of the high-power polarization-maintaining mirror prepared by the actual coating process are continuously detected until the phase difference between S-polarized light and P-polarized light in the polarization parameters of the high-power polarization-maintaining mirror is 0, and the measured average reflectivity is greater than 99%.

[0029] For example, still combined Figure 8 As shown in the process flow, the optimized film structure can be Air / 2.228L (1.117H1.114L)^14 / Sub, that is, the thickness of the low refractive index material of the first film layer 101 is 2.228 times that of a quarter of the incident light wavelength, the thickness of the high refractive index material of the second film layer 102 is 1.117 times that of a quarter of the incident light wavelength, the thickness of the low refractive index material of the second film layer 102 is 1.114 times that of a quarter of the incident light wavelength, and the alternation period of the high refractive index material and the low refractive index material in the second film layer 102 is 14 sets.

[0030] It should be noted that the descriptions of the same steps and contents as in other embodiments in this embodiment can be found in the descriptions in other embodiments, and will not be repeated here.

[0031] The high-power polarization-maintaining mirror, optical equipment, testing system, and film design method provided in this application embodiment include a first film layer, a second film layer, and a substrate sequentially arranged along the incident light direction, with a high power range of 1.61 J / cm². 2 Up to 1.81 J / cm 2 The first film layer is formed by depositing a low-refractive-index material, and the second film layer is formed by alternating deposition of high-refractive-index and low-refractive-index materials. The refractive index of the low-refractive-index material ranges from 1.3 to 1.5, and the refractive index of the high-refractive-index material ranges from 1.8 to 2.3. The extinction coefficients of both the low-refractive-index and high-refractive-index materials are less than 10. -4 It has low absorption and high reflectivity. Test results show that when the azimuth angle of the incident linearly polarized light is in the range of -90 degrees to 90 degrees, the ellipticity difference that can characterize the polarization characteristics is within ±0.3 degrees, corresponding to an extinction ratio of more than 36476:1, which can effectively maintain the stability of the polarization state of the incident light.

[0032] Additionally, embodiments of this application provide a computer-readable storage medium for storing program code used to execute the aforementioned... Figures 7 to 8 The steps of the membrane system design method in the corresponding embodiment.

[0033] Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the membrane system design method of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0034] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0035] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A high-power polarization-maintaining reflector, characterized in that, The high-power polarization-maintaining mirror (10) includes a first film layer (101), a second film layer (102), and a substrate (103) arranged sequentially along the incident light direction, with a high power range of 1.61 J / cm². 2 Up to 1.81 J / cm 2 ; The first film layer (101) is formed by deposition of a low-refractive-index material, and the second film layer (102) is formed by alternating deposition of a high-refractive-index material and the low-refractive-index material. The refractive index of the low-refractive-index material ranges from 1.3 to 1.5, and the refractive index of the high-refractive-index material ranges from 1.8 to 2.

3. The extinction coefficients of both the low-refractive-index material and the high-refractive-index material are less than 10. -4 .

2. The high-power polarization-maintaining reflector according to claim 1, characterized in that, The low-refractive-index material is SiO2, and the high-refractive-index material is HfO2.

3. The high-power polarization-maintaining reflector according to claim 2, characterized in that, The thickness of the low-refractive-index material in the first film layer (101) is 2.228 times the wavelength of one-quarter incident light, the thickness of the high-refractive-index material in the second film layer (102) is 1.117 times the wavelength of one-quarter incident light, the thickness of the low-refractive-index material in the second film layer (102) is 1.114 times the wavelength of one-quarter incident light, and the alternation period of the high-refractive-index material and the low-refractive-index material in the second film layer (102) is 14 sets.

4. The high-power polarization-maintaining reflector according to claim 1, characterized in that, The substrate (103) is a Si substrate, a SiO2 substrate, a Ge substrate, or a sapphire substrate.

5. The high-power polarization-maintaining reflector according to any one of claims 1 to 4, characterized in that, The wavelength range of the incident light is 400nm to 1700nm, and the incident angle is 45 degrees.

6. An optical device, characterized in that, The optical device (20) includes a high-power polarization-maintaining mirror (10) as described in any one of claims 1 to 5.

7. A testing system, characterized in that, The test system (30) is used for polarization maintaining test of the high-power polarization maintaining mirror (10) according to any one of claims 1 to 5. The test system (30) includes a laser (301), a GranTeller prism (302), a half-wave plate (303), the high-power polarization maintaining mirror (10), and a polarization measuring instrument (304) arranged in sequence. The Glan Taylor prism (302) is used to convert the incident light generated by the laser (301) into linearly polarized light; the half-wave plate (303) is used to adjust the azimuth angle of the linearly polarized light; and the polarization measuring instrument (304) is used to receive the reflected light and detect the polarization parameters of the high-power polarization-maintaining mirror (10).

8. The testing system according to claim 7, characterized in that, The polarization measuring instrument (304) is specifically used to collect the first ellipsoid when the high-power polarization-maintaining mirror (10) is not placed in the optical path, to collect the second ellipsoid when the high-power polarization-maintaining mirror (10) is placed in the optical path, and to calculate the difference between the second ellipsoid and the first ellipsoid.

9. A membrane system design method, characterized in that, The film system design method is used for the film system design of the high-power polarization-maintaining mirror according to any one of claims 1 to 5, and the film system design method includes: An initial film structure is constructed, and high-refractive-index and low-refractive-index materials are selected, along with the wavelength and angle of incidence of the incident light. The initial film structure is Air / k1L (k2H k3L)^m / Sub, where Air represents air, Sub represents the substrate, L represents the optical thickness of the low-refractive-index material at one-quarter of the incident light wavelength, H represents the optical thickness of the high-refractive-index material at one-quarter of the incident light wavelength, k1, k2, and k3 represent the coefficients of each one-quarter incident light wavelength optical thickness, and m represents the number of layers, ranging from 10 to 100. The initial film structure was simulated and iteratively optimized, and the polarization parameters of the high-power polarization-maintaining mirror prepared by the actual coating process were continuously detected until the phase difference between S-polarized light and P-polarized light in the polarization parameters of the high-power polarization-maintaining mirror was 0, and the measured average reflectivity was greater than 99%.

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