Preparation method of high-extinction-ratio non-adhesive polarization beam splitting film resistant to high and low temperature environments

Abstract

This invention relates to the field of optical thin film fabrication technology, specifically to a method for fabricating a high extinction ratio, adhesive-free polarizing beam splitter film resistant to high and low temperature environments. The method includes the following steps: S1, substrate pretreatment; S2, polarizing beam splitter film deposition; S3, adhesive-free bonding treatment; S4, annealing strengthening; and S5, post-treatment. This invention uses an adhesive-free optical contact bonding process to replace the traditional organic bonding process, completely eliminating the temperature adaptability bottleneck caused by organic adhesive layers. The bonding interface relies on intermolecular forces for adhesion, eliminating problems such as aging and debonding of organic adhesives. This allows the device to operate stably in a wide temperature range of -60℃ to 120℃, greatly improving the device's environmental adaptability and meeting the needs of extreme environments such as deep space exploration and polar observation.

Description

Technical Field

[0001] This invention relates to the field of optical thin film preparation technology, specifically to a method for preparing a high extinction ratio adhesive-free polarizing beam splitter film resistant to high and low temperature environments. Background Technology

[0002] A polarizing beam splitter is an optical thin film that can split incident unpolarized light into two orthogonally polarized beams. It is one of the core components in systems such as laser communication, photoelectric detection, and quantum information. Traditional polarizing beam splitters typically use two right-angle prisms, with a polarizing beam splitter film deposited on the inclined surface of one of the prisms. The two prisms are then bonded together using optical adhesive to form a cubic structure.

[0003] However, this type of cemented polarizing beam splitter has obvious drawbacks:

[0004] On the one hand, the temperature resistance of organic adhesive layers is limited, and they can usually only work stably in environments ranging from -20℃ to 70℃. In extreme high and low temperature environments, organic adhesives are prone to aging, delamination, and refractive index drift, which leads to a sharp deterioration in the polarization performance of components and cannot meet the usage requirements in extreme environments such as deep space exploration and polar observation.

[0005] On the other hand, the presence of organic adhesives introduces additional absorption and scattering losses, while limiting the laser damage threshold of the components, making them unsuitable for high-power laser system applications. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a high extinction ratio adhesive-free polarizing beam splitter film that can withstand high and low temperature environments, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing a high extinction ratio adhesive-free polarizing beam splitter film resistant to high and low temperature environments includes the following steps:

[0009] S1. Substrate pretreatment: Select two identical right-angle prism substrates, perform ultra-precision polishing on their bevels, and then use RCA standard cleaning process combined with mega-sound cleaning to complete the surface cleaning treatment.

[0010] S2. Polarizing Beam Splitting Film Coating: One of the polished and cleaned prisms is fixed inside the coating machine. After evacuating to the preset vacuum level, high refractive index materials are alternately deposited on the inclined surface of the prism using ion-assisted electron beam evaporation. and low refractive index materials This forms a multilayer polarization beam-splitting film system;

[0011] S3. Adhesive-free bonding treatment: The surfaces of the prisms to be bonded, after the polarization beam splitter film is coated, and another uncoated prism are activated by oxygen plasma. Then, the inclined surfaces of the two prisms are aligned and bonded in a Class 100 clean environment to complete the optical contact bonding.

[0012] S4. Annealing and strengthening: The bonded prism assembly is subjected to constant temperature annealing to strengthen the interfacial bonding strength and eliminate internal stress, resulting in a glue-free polarizing beam splitter prism.

[0013] S5. Post-processing: After annealing, the residual stress of the polarizing beam splitter film on the front surface is calculated based on the Stoney stress formula. The thickness of the stress compensation layer on the back surface is calculated according to the principle of double-sided stress balance. A SiO2 compensation layer of corresponding thickness is deposited on the back surface of the prism. Subsequently, the four light-transmitting surfaces of the prism are polished and anti-reflection coatings for the working band are deposited.

[0014] Preferably, in step S1, the right-angle prism substrate is K9 glass or ultraviolet fused silica glass.

[0015] Preferably, in step S1, the RCA standard cleaning process specifically includes:

[0016] Use in sequence The mixture was cleaned at 75°C for 10 minutes, with megahertz treatment activated during the process; subsequently, it was used... The mixture was cleaned at 75°C for 10 minutes, with megason treatment also applied during the cleaning process. After cleaning, it was rinsed with ultrapure deionized water for 5 minutes, and then dried with high-purity nitrogen to complete the surface cleaning treatment.

[0017] Preferably, in step S2, during the ion-assisted deposition process, the operating parameters of the ion source are: beam current 130-150mA, accelerating voltage 110-120V, and argon flow rate 12-15sccm, and the ion source is continuously turned on throughout the entire film deposition process.

[0018] Preferably, in step S2, the multilayer polarization beam-splitting film system adopts a Fabry-Perot basic structure, and the optimized film system structure is as follows:

[0019] in, Represents the prism substrate. Represents air medium. Represents the optical thickness at 1 / 4 of the reference wavelength. High refractive index film, Represents the optical thickness at 1 / 4 of the reference wavelength. Low refractive index film layers, the superscript number represents the number of repetition cycles of the corresponding film stack.

[0020] Preferably, in step S2, the material selection is determined according to the polarization bandwidth calculation formula, which is:

[0021] in, The effective polarization working bandwidth of the polarization beam splitter; The width of the S-polarized high reflectivity region; The width of the P-polarized high reflectivity region; High refractive index material right The equivalent refractive index of polarized light; Low refractive index material right The equivalent refractive index of polarized light; High refractive index material right The equivalent refractive index of polarized light, Low refractive index material right The equivalent refractive index of polarized light.

[0022] Preferably, in step S4, during the annealing process, the residual stress of the film layer is quantitatively calculated using the Stoney formula, which is:

[0023] in, For the residual stress of the thin film, Young's modulus based on the base For the base thickness, Poisson's ratio with a base of 1 This represents the total thickness of the film. Let be the radius of curvature of the substrate after coating. The initial radius of curvature of the substrate before coating.

[0024] Preferably, in step S5, the two-sided stress balance principle satisfies the following calculation formula:

[0025] in, For the first Stress in the thin film, For the first The thickness of the thin film, The formula represents the total number of thin film layers on the corresponding surface of the substrate. The thickness of the back surface compensation layer is calculated using this formula to achieve stress balance on both sides of the substrate.

[0026] Preferably, the extinction ratio of the prepared polarizing beam splitter film satisfies the following calculation formula:

[0027] in, Extinction ratio, Let be the transmittance of P-polarized light. The transmittance of S-polarized light is given. The extinction ratio of the device prepared by this method can reach more than 12000:1 at room temperature.

[0028] Preferably, the operating wavelength is the 1530nm to 1565nm optical communication wavelength band.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] This invention uses a glue-free optical contact bonding process to replace the traditional organic bonding process, completely eliminating the temperature adaptability bottleneck caused by organic adhesive layers. The bonding interface relies on intermolecular forces to achieve bonding, eliminating problems such as aging and debonding of organic adhesives. This allows the components to operate stably in a wide temperature range of -60℃ to 120℃, greatly improving the environmental adaptability of the components and meeting the usage requirements of extreme environments such as deep space exploration and polar observation.

[0031] This invention selects When SiO2 is used as the film material, the coefficient of thermal expansion of both is highly matched with that of substrate materials such as K9 and fused silica. Combined with ion-assisted deposition process, the prepared film has high density and low stress. During high and low temperature cycling, the film will not crack or fall off. At the same time, the optimized 31-layer all-dielectric film system achieves an extinction ratio of more than 12000:1, which is far superior to the performance of traditional polarization beam splitting films and meets the requirements of high-sensitivity coherent laser communication systems.

[0032] The adhesive-free structure of this invention eliminates the absorption and scattering losses of organic adhesives, while improving the laser damage threshold of the element, making it suitable for high-power laser system applications. In addition, the interface of optical contact bonding does not have temperature drift of refractive index, and the polarization performance of the element is stable during temperature changes. The extinction ratio change rate is small after high and low temperature cycling, and the performance stability is excellent. Attached Figure Description

[0033] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Please see Figure 1As shown, this invention discloses a method for preparing a high extinction ratio adhesive-free polarizing beam splitter film resistant to high and low temperature environments, comprising the following steps:

[0036] S1. Substrate pretreatment: Select two identical right-angle prism substrates. The right-angle prism substrates are K9 glass or UV fused silica glass. Perform ultra-precision polishing on their bevels. Then, use RCA standard cleaning process combined with mega-sound cleaning to complete the surface cleaning process.

[0037] The RCA standard cleaning process is as follows:

[0038] Use in sequence The mixture was cleaned at 75°C for 10 minutes, with megahertz treatment activated during the process; subsequently, it was used... The mixture was cleaned at 75°C for 10 minutes, with megason treatment also applied during the cleaning process; after cleaning, it was rinsed with ultrapure deionized water for 5 minutes, and then dried with high-purity nitrogen to complete the surface cleaning treatment.

[0039] S2. Polarizing beam splitter coating: Fix one of the polished and cleaned prisms inside the coating machine, and evacuate to 3.0× After achieving a preset vacuum level of Pa, the substrate was heated to 280–300°C and held for 30 minutes to remove adsorbed gases. Subsequently, the ion source was activated to perform ion beam cleaning of the substrate for 5 minutes. The operating parameters of the ion source were: beam current 130–150 mA, accelerating voltage 110–120 V, and argon flow rate 12–15 sccm. The ion source remained continuously activated throughout the entire film deposition process. After cleaning, ion-assisted electron beam evaporation was used to alternately deposit high-refractive-index materials on the inclined surface of the prism. For low-refractive-index material SiO2, the LightRatioPeak optical value ratio method is used to monitor and control the film thickness in real time during the deposition process. The evaporation rate is 0.4 nm / s. The evaporation rate is 0.6 nm / s, ultimately forming a 31-layer multilayer polarization beam splitting film system;

[0040] The multilayer polarization beam-splitting film system adopts the Fabry-Perot basic structure, and the optimized film system structure is as follows:

[0041]

[0042] in, Represents the prism substrate. Represents air medium. Represents the optical thickness at 1 / 4 of the reference wavelength. High refractive index film, Represents the optical thickness at 1 / 4 of the reference wavelength. Low refractive index film layer, the superscript number represents the number of repetition cycles of the corresponding film stack;

[0043] Material selection is determined based on the polarization bandwidth calculation formula, which is:

[0044] in, The effective polarization working bandwidth of the polarization beam splitter; The width of the S-polarized high reflectivity region; The width of the P-polarized high reflectivity region; High refractive index material right The equivalent refractive index of polarized light; Low refractive index material right The equivalent refractive index of polarized light; High refractive index material right The equivalent refractive index of polarized light, Low refractive index material right The equivalent refractive index of polarized light;

[0045] S3. Adhesive-free bonding treatment: The surfaces of the prisms to be bonded, after the polarization beam splitter film is coated, and another uncoated prism are subjected to oxygen plasma activation treatment. The treatment parameters are power 50W, oxygen flow rate 50sccm, and treatment time 30s. Then, in a Class 100 clean environment, the inclined surfaces of the two prisms are aligned and bonded. During the process, a white light interferometer is used to monitor the interference fringes at the bonding interface. The relative orientation of the prisms is adjusted until the Newton interference fringes at the interface are reduced to less than one, thus completing the optical contact bonding.

[0046] S4. Annealing and Strengthening: Place the bonded prism assembly into a vacuum annealing furnace and evacuate to 1.0× After Pa, the temperature is increased to 200-220℃ at a rate of 2℃ / min and held for 5-6 hours. Then, the temperature is slowly reduced to room temperature at a rate of 0.8℃ / min to complete the annealing process, strengthen the interfacial bonding strength, eliminate internal stress, and obtain the glue-free polarizing beam splitter prism.

[0047] S5. Post-processing: After annealing, the residual stress of the polarization beam-splitting film on the front surface is calculated based on the Stoney stress formula. The residual stress of the film layer is quantified using the Stoney formula, which is:

[0048] in, For the residual stress of the thin film, Young's modulus based on the base For the base thickness, Poisson's ratio with a base of 1 This represents the total thickness of the film. Let be the radius of curvature of the substrate after coating. The initial radius of curvature of the substrate before coating;

[0049] The thickness of the surface stress compensation layer is calculated based on the principle of double-sided stress balance, which satisfies the following calculation formula:

[0050] in, For the first Stress in the thin film, For the first The thickness of the thin film, The total number of thin film layers on the corresponding surface of the substrate is given by the formula. The thickness of the back surface compensation layer is calculated to achieve stress balance on both sides of the substrate. A SiO2 compensation layer of the corresponding thickness is deposited on the back surface of the prism. Subsequently, the four light-transmitting surfaces of the prism are polished and an anti-reflection coating for the working wavelength is deposited. The extinction ratio of the prepared polarization beam-splitting film satisfies the following calculation formula:

[0051] in, Extinction ratio, Let be the transmittance of P-polarized light. The transmittance of S-polarized light is given. The extinction ratio of the device prepared by this method can reach more than 12000:1 at room temperature, and the working wavelength is the optical communication band of 1530nm to 1565nm.

[0052] Example 1

[0053] This embodiment uses K9 glass as a substrate to fabricate a glue-free polarizing beam splitter prism with a working wavelength range of 1530nm to 1565nm. The specific steps are as follows:

[0054] S1. Substrate pretreatment: Select two K9 glass right-angle prism substrates with dimensions of 10mm×10mm×10mm. First, perform ultra-precision chemical mechanical polishing on the inclined surfaces of the two prisms. After polishing, the surface roughness of the inclined surfaces is Ra=0.08nm and the flatness is λ / 12 632.8nm, which meets the accuracy requirements of optical contact bonding.

[0055] The two prisms were then cleaned: First, the prisms were ultrasonically cleaned in acetone solution for 10 minutes to remove polishing residue from the surface; then, the RCA standard cleaning process was adopted, using a mixture of NH4OH:H2O2:H2O=1:1:5 at 75°C for 10 minutes, with megaphonic processing at 950kHz and a power density of 10W / cm²; subsequently, a mixture of HCl:H2O2:H2O=1:1:6 was used for 10 minutes at 75°C, again supplemented with megaphonic processing; after cleaning, the prisms were rinsed with ultrapure deionized water for 5 minutes, and then dried with high-purity nitrogen to complete the substrate pretreatment.

[0056] S2. Polarizing beam splitter coating: Fix one of the pre-treated prisms onto the workpiece tray of the vacuum coating machine, close the coating machine chamber, and evacuate to 3.0×10⁻⁻⁶. 4 Pa, then the substrate temperature was heated to 280℃ and held for 30 min to remove adsorbed gas from the substrate surface. Then the ion source was turned on to perform ion beam cleaning on the substrate surface for 5 min. The ion source parameters were: beam current 130mA, accelerating voltage 110V, and argon flow rate 12sccm.

[0057] After cleaning, the film deposition process began: first, Ta₂O₅ was evaporated at a rate of 0.4 nm / s, achieving a deposition thickness of 12.3 nm; then, SiO₂ was evaporated at a rate of 0.6 nm / s, achieving a deposition thickness of 81.5 nm. Following the pre-defined film structure, Ta₂O₅ and SiO₂ were deposited alternately. Throughout the deposition process, the ion source remained continuously activated for auxiliary deposition, resulting in a total of 31 layers deposited, completing the polarization beam splitter film deposition. After deposition, the substrate temperature was lowered to room temperature, and the prism was removed.

[0058] S3. Glue-free bonding treatment: Place the coated prism and another uncoated prism into a plasma treatment device for oxygen plasma activation treatment. The treatment parameters are: power 50W, oxygen flow rate 50sccm, and treatment time 30s. After treatment, quickly transfer the two prisms to a Class 100 clean bench, align the bevels of the two prisms, and slowly bond them together. During the process, monitor the interference fringes at the bonding interface using a white light interferometer, and adjust the relative orientation of the two prisms until the Newtonian interference fringe at the interface is reduced to one. Confirm that there are no air bubbles or gaps at the interface, thus completing the optical contact bonding.

[0059] S4. Annealing and strengthening: The bonded prism assembly is placed in a vacuum annealing furnace, evacuated to 1.0×10⁻³Pa, and then heated to 200℃ at a rate of 2℃ / min and held for 5 hours. Subsequently, it is slowly cooled to room temperature at a rate of 0.8℃ / min to complete the annealing treatment, strengthen the bond strength, and eliminate internal stress.

[0060] S5. Post-processing: After annealing, the four light-transmitting surfaces of the prism are finely polished, and then an anti-reflection coating with a wavelength range of 1530nm to 1565nm is deposited on the light-transmitting surfaces. The residual reflectivity of the anti-reflection coating is ≤0.1%, and finally, the finished glue-free polarizing beam splitter prism is obtained.

[0061] The performance of the finished product prepared in this embodiment was tested:

[0062] First, the performance at room temperature was tested. At an incident angle of 45° and a wavelength of 1550nm, the transmittance of p-polarized light was 98.7%, the reflectance of s-polarized light was 99.6%, and the extinction ratio was 12500:1.

[0063] Then, high and low temperature cycling tests were conducted. The components were placed in a high and low temperature test chamber and subjected to temperature cycling from -60℃ to 120℃. Each cycle consisted of holding at -60℃ for 1 hour, then raising the temperature to 120℃ and holding for 1 hour, and then lowering the temperature to -60℃. A total of 50 cycles were performed.

[0064] After the cycle was completed, the performance of the component was tested again. The p-polarized transmittance at 1550nm was 98.5%, the s-polarized reflectance was 99.5%, the extinction ratio was 11800:1, and the extinction ratio change rate was only 5.6%. The component showed no delamination or film cracking, and its performance was stable.

[0065] Example 2

[0066] The difference between this embodiment and Embodiment 1 is that the substrate is ultraviolet fused silica glass, while the other steps are the same, as follows:

[0067] In step S1, two 10mm×10mm×10mm UV fused silica right-angle prisms are selected. The roughness of the polished bevel surface Ra=0.07nm and the flatness is λ / 13@632.8nm. The cleaning steps are the same as in Example 1.

[0068] In step S2, the coating steps are the same, the film structure is the same, and the substrate temperature is set to 300℃.

[0069] In step S3, the plasma activation and bonding steps are the same.

[0070] In step S4, the annealing temperature is set to 220℃ and held for 6 hours.

[0071] Performance testing: The extinction ratio at 1550nm at room temperature is 13200:1. After 50 cycles of high and low temperatures, the extinction ratio is 12700:1, with a change rate of 3.8%. The performance remains stable. Furthermore, the fused silica substrate can adapt to a wider wavelength range and can be used for multi-band applications from ultraviolet to near-infrared.

[0072] Example 3

[0073] The difference between this embodiment and Embodiment 1 is that, during the coating process, the parameters of the ion source are adjusted to: beam current 150mA, accelerating voltage 120V, and argon flow rate 15sccm, while the other steps are the same.

[0074] Test results: The film has higher density and lower stress. After high and low temperature cycling, the extinction ratio changed from 12800:1 to 12400:1, with a change rate of only 3.1%. The performance is more stable and can adapt to more severe temperature shock environments.

[0075] To verify the technical advantages of the present invention, the performance of the embodiments of the present invention was compared with that of a traditional glued polarizing beam splitter and an existing glueless polarizing beam splitter. The results are shown in Table 1 below:

[0076] Table 1. Performance Comparison Table

[0077]

[0078] As can be seen from the above comparison, the polarization beam splitter prism prepared by the method of the present invention is significantly superior to traditional products and existing glue-free products in terms of operating temperature range, extinction ratio, environmental stability and laser damage threshold, and can meet the usage requirements of extreme scenarios such as deep space exploration and high-power laser communication.

[0079] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high extinction ratio adhesive-free polarizing beam splitter film resistant to high and low temperature environments, characterized in that, Includes the following steps: S1. Substrate pretreatment: Select two identical right-angle prism substrates, perform ultra-precision polishing on their bevels, and then use RCA standard cleaning process combined with mega-sound cleaning to complete the surface cleaning treatment. S2. Polarizing Beam Splitting Film Coating: One of the polished and cleaned prisms is fixed inside the coating machine. After evacuating to the preset vacuum level, high refractive index materials are alternately deposited on the inclined surface of the prism using ion-assisted electron beam evaporation. and low refractive index materials This forms a multilayer polarization beam-splitting film system; S3. Adhesive-free bonding treatment: The surfaces of the prisms to be bonded, after the polarization beam splitter film is coated, and another uncoated prism are activated by oxygen plasma. Then, the inclined surfaces of the two prisms are aligned and bonded in a Class 100 clean environment to complete the optical contact bonding. S4. Annealing and strengthening: The bonded prism assembly is subjected to constant temperature annealing to strengthen the interfacial bonding strength and eliminate internal stress, resulting in a glue-free polarizing beam splitter prism. S5. Post-processing: After annealing, the residual stress of the polarizing beam splitter film on the front surface is calculated based on the Stoney stress formula. The thickness of the stress compensation layer on the back surface is calculated according to the principle of double-sided stress balance. A SiO2 compensation layer of corresponding thickness is deposited on the back surface of the prism. Subsequently, the four light-transmitting surfaces of the prism are polished and anti-reflection coatings for the working band are deposited.

2. The method for preparing a high extinction ratio adhesive-free polarizing beam splitter film resistant to high and low temperature environments according to claim 1, characterized in that, In step S1, the right-angle prism substrate is K9 glass or ultraviolet fused silica glass.

3. The method for preparing a high extinction ratio adhesive-free polarizing beam splitter film resistant to high and low temperature environments according to claim 1, characterized in that, In step S1, the RCA standard cleaning process specifically includes: Use in sequence The mixture was cleaned at 75°C for 10 minutes, with megahertz treatment activated during the process; Then use The mixture was cleaned at 75°C for 10 minutes, with megaphonic treatment also applied during the cleaning process. After cleaning, rinse with ultrapure deionized water for 5 minutes, then dry with high-purity nitrogen to complete the surface cleaning process.

4. The method for preparing a high extinction ratio adhesive-free polarizing beam splitter film resistant to high and low temperature environments according to claim 1, characterized in that, In step S2, during the ion-assisted deposition process, the operating parameters of the ion source are: beam current 130-150mA, accelerating voltage 110-120V, and argon flow rate 12-15sccm, and the ion source is continuously turned on throughout the entire film deposition process.

5. The method for preparing a high extinction ratio adhesive-free polarizing beam splitter film resistant to high and low temperature environments according to claim 1, characterized in that, In step S2, the multilayer polarization beam splitting film system adopts the Fabry-Perot basic structure, and the optimized film system structure is as follows: in, Represents the prism substrate. Represents air medium. Represents the optical thickness at 1 / 4 of the reference wavelength. High refractive index film, Represents the optical thickness at 1 / 4 of the reference wavelength. Low refractive index film layers, the superscript number represents the number of repetition cycles of the corresponding film stack.

6. The method for preparing a high extinction ratio adhesive-free polarizing beam splitter film resistant to high and low temperature environments according to claim 1, characterized in that, In step S2, the material selection is determined according to the polarization bandwidth calculation formula, which is: in, The effective polarization working bandwidth of the polarization beam splitter; The width of the S-polarized high reflectivity region; The width of the P-polarized high reflectivity region; High refractive index material right The equivalent refractive index of polarized light; Low refractive index material right The equivalent refractive index of polarized light; High refractive index material right The equivalent refractive index of polarized light, Low refractive index material right The equivalent refractive index of polarized light.

7. The method for preparing a high extinction ratio adhesive-free polarizing beam splitter film resistant to high and low temperature environments according to claim 1, characterized in that, In step S4, during the annealing process, the residual stress of the film layer is quantitatively calculated using the Stoney formula, which is: in, For the residual stress of the thin film, Young's modulus based on the base For the base thickness, Poisson's ratio with a base of 1 This represents the total thickness of the film. Let be the radius of curvature of the substrate after coating. The initial radius of curvature of the substrate before coating.

8. The method for preparing a high extinction ratio adhesive-free polarizing beam splitter film resistant to high and low temperature environments according to claim 1, characterized in that, In step S5, the principle of two-sided stress balance satisfies the following calculation formula: in, For the first Stress in the thin film, For the first The thickness of the thin film, The formula represents the total number of thin film layers on the corresponding surface of the substrate. The thickness of the back surface compensation layer is calculated using this formula to achieve stress balance on both sides of the substrate.

9. The method for preparing a high extinction ratio adhesive-free polarizing beam splitter film resistant to high and low temperature environments according to claim 1, characterized in that, The extinction ratio of the prepared polarization beam-splitting film satisfies the following calculation formula: in, Extinction ratio, Let be the transmittance of P-polarized light. The transmittance of S-polarized light is given. The extinction ratio of the device prepared by this method can reach more than 12000:1 at room temperature.

10. The method for preparing a high extinction ratio adhesive-free polarizing beam splitter film resistant to high and low temperature environments according to claim 1, characterized in that, The operating wavelength is the 1530nm~1565nm optical communication wavelength band.

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