Near-infrared optical lens and method for manufacturing the same, and silicon-based lens for wavelength division multiplexing module of optical communication

Abstract

The present application provides a near-infrared optical lens, comprising a silicon substrate and AR film system structures symmetrically arranged on both sides of the silicon substrate, the AR film system structure is sub / 0.5(HL)^2(0.5H)K / Air, and the transmittance of the near-infrared optical lens to light in the wavelength range of 1260-1620 nm is above 90%. Through the matching design of the film layer material, the film layer structure and the thickness, the near-infrared optical lens shows the advantages of low reflection and high transmission in the wavelength of 1260-1620 nm, which is much better than the products on the market, and the film layer has good adhesion, moderate friction resistance, and good constant temperature and humidity resistance, and can be applied to the silicon-based lens of the wavelength division multiplexing module of optical communication.

Description

Technical Field

[0001] This invention belongs to the field of optical fiber communication technology, specifically relating to the design and preparation method of a thin film with a full-band wavelength range of 1260-1620nm that is resistant to friction, resistant to constant temperature and humidity, and has high transmittance, deposited on a silicon-based lens of an optical fiber communication module. Background Technology

[0002] The working principle of optical fiber communication systems is mainly based on wavelength multiplexing technology, which allows multiple optical signals of different wavelengths to be transmitted simultaneously in a single optical fiber. This technology involves two key processes: multiplexing and demultiplexing.

[0003] Multiplexing involves precisely aligning and combining multiple signals from different light sources at the transmitting end using a series of optical elements. The combined signal is then transmitted through a single optical fiber. Demultiplexing works on the opposite principle. Silicon-based lenses in optical communication modules are used for optical path focusing and collimation, effectively reducing energy loss. Figure 1 As shown.

[0004] However, commercially available silicon-based lenses often have low transmittance (or high reflectance when measured with low reflectance), which fails to significantly reduce energy loss. Furthermore, the film layer may not withstand moderate friction and 48-hour high-temperature and high-humidity tests. Therefore, they cannot meet the requirements for long-term stable operation in optical communication. Summary of the Invention

[0005] To address the aforementioned technical issues, this application proposes near-infrared optical lenses and their fabrication methods, as well as silicon-based lenses for optical communication wavelength division multiplexing modules.

[0006] To achieve the above objectives, this application proposes the following technical solution:

[0007] In a first aspect, a near-infrared optical lens is provided, comprising a silicon substrate and an AR film structure symmetrically disposed on both sides of the silicon substrate. The AR film structure is sub / 0.5(HL)^2(0.5H)K / Air, where H represents a high refractive index layer of one basic thickness, L represents a first low refractive index layer of one basic thickness, and K represents a second low refractive index layer of one basic thickness. The basic thickness corresponding to one H, one L, or one K represents that the film layer has 1 / 4 optical thickness at a reference wavelength. The near-infrared optical lens has an average transmittance of over 90% for light in the wavelength range of 1260~1620nm.

[0008] Preferably, the near-infrared optical lens has an average transmittance of 95% or more for light in the wavelength range of 1260~1620nm, and more preferably 99% or more.

[0009] Preferably, the high refractive index layer is a Ti3O5 layer, the first low refractive index layer is a SiO2 layer, and the second low refractive index layer is a MgF2 layer.

[0010] Preferably, the AR film system structure comprises, in sequence, a first Ti3O5 layer, a first SiO2 layer, a second Ti3O5 layer, a second SiO2 layer, a third Ti3O5 layer, and a MgF2 layer on the surface of the silicon substrate; the first Ti3O5 layer has a thickness of 165-170 nm, the first SiO2 layer has a thickness of 222-227 nm, the second Ti3O5 layer has a thickness of 65-70 nm, the second SiO2 layer has a thickness of 100-105 nm, the third Ti3O5 layer has a thickness of 130-135 nm, and the MgF2 layer has a thickness of 267-272 nm.

[0011] Preferably, the first Ti3O5 layer has a thickness of 168.27 nm, the first SiO2 layer has a thickness of 225.17 nm, the second Ti3O5 layer has a thickness of 67.7 nm, the second SiO2 layer has a thickness of 102.66 nm, the third Ti3O5 layer has a thickness of 133.3 nm, and the MgF2 layer has a thickness of 269.23 nm.

[0012] In a second aspect, a method for preparing a near-infrared optical lens is provided, comprising:

[0013] An AR film system structure is coated on the first surface of the silicon substrate, the AR film system structure comprising, in sequence, a high refractive index layer, a first low refractive index layer, a high refractive index layer, a first low refractive index layer, a high refractive index layer, and a second low refractive index layer;

[0014] An AR film system structure identical to that on the first surface is coated on the second surface of the silicon substrate;

[0015] Cooling to room temperature, thereby obtaining the near-infrared optical lens.

[0016] Preferably, before coating the film layers on the first surface and the second surface of the silicon substrate, the method further comprises: placing the silicon substrate into a coating machine, vacuumizing to 1.5×10 -3 ~2×10 -3 Pa, preheating to 115-125℃, and performing ion source cleaning.

[0017] Preferably, the coating temperature of each film layer is 115-125℃.

[0018] Preferably, the deposition rate of each high refractive index layer is 2.5-3.5 Å / S, the deposition rate of each first low refractive index layer is 4.5-5.5 Å / S, and the deposition rate of the second low refractive index layer is 4.5-5.5 Å / S.

[0019] Preferably, the plating method of each film layer is vacuum electron beam evaporation plating.

[0020] Preferably, the deposition of the second low refractive index layer is assisted by an RF ion source; the RF ion source parameters are a voltage of 280-320 V, a current of 280-320 mA, an ACC voltage of 180-220 V, an argon gas flow of 38-42 sccm, and an argon gas flow of 7-9 sccm in the neutralizer.

[0021] Preferably, the deposition of each high refractive index layer is assisted by an RF ion source; the RF ion source parameters are a voltage of 1000-1100 V, a current of 860-940 mA, an ACC voltage of 570-630 V, an oxygen gas flow of 65-75 sccm, and an argon gas flow of 7-9 sccm in the neutralizer.

[0022] Preferably, the deposition of each first low refractive index layer is assisted by an RF ion source; the RF ion source parameters are a voltage of 860-940 V, a current of 860-940 mA, an ACC voltage of 570-630 V, an oxygen gas flow of 45-55 sccm, and an argon gas flow of 7-9 sccm in the neutralizer.

[0023] Preferably, before the silicon substrate is placed in the plating machine, the silicon substrate is polished and cleaned.

[0024] Preferably, the film thickness is monitored by back reflection light control during the plating process.

[0025] Preferably, after the plating on both sides of the silicon substrate is completed, the silicon substrate is removed after being cooled to below 70℃.

[0026] In a third aspect, a silicon-based lens for an optical communication wavelength division multiplexing module is provided, which comprises the near-infrared optical lens described above or the near-infrared optical lens prepared by the preparation method described above.

[0027] Compared with the prior art, one or more of the above technical solutions can achieve at least one of the following beneficial effects:

[0028] The provided near-infrared optical lens comprises a silicon substrate and an AR film system structure symmetrically arranged on both sides of the silicon substrate. Through the matching design of the film layer material, the film layer structure, and the thickness, the near-infrared optical lens exhibits the advantages of low reflection and high transmission in the wavelength of 1260-1620 nm, which is much better than the products on the market. The film layer has good adhesion, good resistance to moderate friction, and good resistance to constant temperature and humidity, and can be applied to the silicon-based lens for an optical communication wavelength division multiplexing module.

[0029] The provided preparation method of the near-infrared optical lens optimizes the preparation process, which is conducive to further improving the adhesion, resistance to moderate friction, and resistance to constant temperature and humidity of the film system. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative effort.

[0031] Figure 1 Schematic diagram of a silicon-based lens in an optical communication module.

[0032] Figure 2 Low reflectance spectrum of the silicon substrate film system designed in Example 1.

[0033] Figure 3 Low reflectance spectrum of the silicon substrate film system designed in Example 1.

[0034] Figure 4 Low reflectance spectrum of the silicon substrate film system designed in Example 1.

[0035] In the drawings, the reference signs are as follows:

[0036] 1, laser; 2, converging silicon lens; 3, focusing lens; 4, silicon lens array; 5, filter; 6, Z-block; 7, 1 / 4 wave plate; 8, optical isolator; 9, collimating silicon lens. DETAILED DESCRIPTION

[0037] The present application provides a near-infrared optical lens, comprising a silicon substrate and AR film system structures symmetrically arranged on both sides of the silicon substrate, the AR film system structure is sub / 0.5(HL)^2(0.5H)K / Air, i.e. sub / (0.5H0.5L)^2(0.5H)K / Air, wherein H represents a high refractive layer with a basic thickness, L represents a first low refractive layer with a basic thickness, and K represents a second low refractive layer with a basic thickness, wherein the basic thickness corresponding to one H or one L or one K represents that the film layer has a 1 / 4 optical thickness at a reference wavelength; the average transmittance of the near-infrared optical lens to light in the wavelength range of 1260-1620 nm is above 90%.

[0038] In some preferred embodiments, the average transmittance of the near-infrared optical lens to light in the wavelength range of 1260-1620 nm is above 99%, for example, 99.0%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, etc.

[0039] In some preferred embodiments, the high refractive index layer is a Ti3O5 layer, the first low refractive index layer is a SiO2 layer, and the second low refractive index layer is a MgF2 layer.

[0040] In some preferred embodiments, the AR film structure includes a first Ti3O5 layer, a first SiO2 layer, a second Ti3O5 layer, a second SiO2 layer, a third Ti3O5 layer, and a MgF2 layer sequentially disposed on the surface of a silicon substrate; the thickness of the first Ti3O5 layer is 165~170nm, the thickness of the first SiO2 layer is 222~227nm, the thickness of the second Ti3O5 layer is 65~70nm, the thickness of the second SiO2 layer is 100~105nm, the thickness of the third Ti3O5 layer is 130~135nm, and the thickness of the MgF2 layer is 267~272nm.

[0041] In some preferred embodiments, the thickness of the first Ti3O5 layer is 168.27 nm, the thickness of the first SiO2 layer is 225.17 nm, the thickness of the second Ti3O5 layer is 67.7 nm, the thickness of the second SiO2 layer is 102.66 nm, the thickness of the third Ti3O5 layer is 133.3 nm, and the thickness of the MgF2 layer is 269.23 nm.

[0042] In some embodiments, the average reflectivity of the silicon-based antireflective film at wavelengths of 1260-1620 μm can be as low as 0.17%, and the maximum reflectivity at wavelengths of 1260-1620 μm can be as low as 0.20%.

[0043] This invention provides a method for preparing a near-infrared optical lens, comprising:

[0044] An AR film structure is deposited on the first surface of a silicon substrate. The AR film structure includes a high refractive index layer, a first low refractive index layer, a high refractive index layer, a first low refractive index layer, a high refractive index layer, and a second refractive index layer arranged sequentially.

[0045] The same AR film structure as the first surface is sequentially deposited on the second surface of the silicon substrate;

[0046] The near-infrared optical lens is obtained by cooling to room temperature.

[0047] In a partially preferred embodiment, before depositing the film layer on the first surface and the film layer on the second surface of the silicon substrate, the method further includes: placing the silicon substrate in a coating machine and evacuating it to a vacuum of 1.5 × 10⁻⁶. -3 ~2×10 -3 Pa, preheat to 115~125℃, and perform ion source cleaning.

[0048] Before ion source cleaning, the membrane material is pre-melted, degassed, and impurities removed to ensure its purity.

[0049] Ion source cleaning can remove oxide layers and adhering particles from the surface of products and substrates, resulting in a cleaner surface and increased film adhesion. The ion source can be an RF source with parameters of 750±2V voltage, 750±2mA current, 600±2V ACC voltage, and oxygen filling volume of 70±1 sccm or argon of 8 sccm.

[0050] In some preferred embodiments, the deposition temperature of each film layer is 115~125°C.

[0051] In some preferred embodiments, the deposition rate of each high refractive index layer is 2.5~3.5 Å / S; the deposition rate of each first low refractive index layer is 4.5~5.5 Å / S; and the deposition rate of the second low refractive index layer is 4.5~5.5 Å / S.

[0052] In some preferred embodiments, the deposition of the second low-refractive-index layer is performed with the assistance of an RF ion source; the parameters of the RF ion source are: voltage 280~320V, current 280~320mA, ACC voltage 180~220V, gas filling volume of argon 38~42sccm, and neutralizer argon 7~9sccm.

[0053] In some preferred embodiments, the deposition of each high refractive index layer is carried out with the assistance of an RF ion source; the parameters of the RF ion source are: voltage 1000~1100V, current 860~940mA, ACC voltage 570~630V, gas filling volume of oxygen 65~75sccm, and neutralizer argon 7~9ssccm.

[0054] In some preferred embodiments, the deposition of each first low-refractive-index layer is performed with the assistance of an RF ion source; the parameters of the RF ion source are: voltage 860~940V, current 860~940mA, ACC voltage 570~630V, gas filling volume of oxygen 45~55sccm, and neutralizer argon 7~9sccm.

[0055] In some preferred embodiments, the silicon substrate is polished and cleaned before being placed into the coating machine. Back-reflection light is used to monitor the film thickness during the coating process.

[0056] In some preferred embodiments, after coating both sides of the silicon substrate, it is removed after being stepped down to below 70°C. More preferably, after coating, it is first held at 115-125°C for 15 minutes, then stepped down to below 65-75°C before removal. Preferably, the stepped cooling is as follows: first, the temperature is lowered to 95-105°C and held for 5 minutes, then lowered to 75-85°C and held for 5 minutes, and finally lowered to below 65-75°C before opening the door to remove the component.

[0057] The present invention also provides a silicon-based lens for an optical communication wavelength division multiplexing module, including the aforementioned near-infrared optical lens or near-infrared optical lens, specifically, the silicon-based lens for the optical communication wavelength division multiplexing module is the near-infrared optical lens.

[0058] To facilitate understanding of the present invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0059] Example 1

[0060] The implementation process of the disclosed method for fabricating silicon-based lens films is as follows:

[0061] Film system design: The film system design uses 550nm as the center wavelength for optical thin film design. The film stack formula is: sub / 0.5(HL)^4(0.5H) K / Air, where Sub is the substrate material silicon, the substrate product is a D0.5±0.05mm*1±0.05mm lens, and the accompanying wafer is a 25±0.1mm*3±0.1mm wedge. Air represents air in the film stack expression:

[0062] L represents SiO2 (silicon dioxide), a low-refractive-index material with a thickness of 1 / 4 wavelength.

[0063] H represents a high-refractive-index Ti3O5 (titanium pentoxide) with a thickness of 1 / 4 wavelength.

[0064] K represents MgF2 (magnesium fluoride), a low-refractive-index material with a thickness of 1 / 4 wavelength.

[0065] The final film stack size on both surfaces of the silicon substrate was determined to be sub / 0.5(HL)^2(0.5H) K / Air, with a film thickness of:

[0066] sub / Ti3O5 (168.27nm) / SiO2 (225.17nm) / Ti3O5 (67.7nm) / SiO2 (102.66nm) / Ti3O5 (133.3nm) / MgF2 (269.23nm) / Air; The low-reflectance spectrum of the designed film is as follows: Figure 2 As shown.

[0067] Step 1: The silicon-based lens and the substrate to be coated are cleaned and polished with alumina polishing solution, followed by ultrasonic cleaning; the coating machine is a Guangchi OTFC1300. The film thickness is entered into the coating file, and parameters such as coating temperature, evaporation rate, coating vacuum, ion source voltage, current, and gas filling amount are set.

[0068] Step 2: Clamp the pre-cleaned product and the substrate to be coated, then place them on the umbrella frame of the coating machine. Close the door and evacuate the air. Set the coating temperature to 120℃; the base vacuum before coating is 1.5×10. -3 Pa; The deposition rate of Ti3O5 film is set to 3 Å / s; the deposition rate of SiO2 film is set to 5 Å / s; the deposition rate of MgF2 film is set to 5 Å / s;

[0069] Step 3: Before coating, pre-melt, degas, and remove impurities from the film material to ensure its purity.

[0070] Step 4: The cavity vacuum level reaches 1.5 × 10⁻⁶. -3 Pa, start the RF source to perform ion cleaning on the lens and the coating, remove the oxide layer and attached particles on the surface of the product and the coating, make the surface cleaner, and increase the adhesion of the film. The cleaning time is 200s, the parameters are voltage 750V, current 750mA, ACC voltage 600V, and gas filling volume of oxygen 70sccm and argon 8sccm.

[0071] Step 5: After the ion source is cleaned, the coating process begins. Vacuum electron beam evaporation is used for coating, and back-reflection light is used to monitor the film thickness, resulting in smaller errors and higher precision compared to crystal monitoring. For Ti3O5 film deposition, the ion source parameters are: voltage 1050V, current 900mA, ACC voltage 600V, oxygen charge 70sccm, and argon charge 8sccm in the neutralizer. For SiO2 film deposition, the ion source parameters are: voltage 900V, current 900mA, ACC voltage 600V, oxygen charge 50sccm, and argon charge 8sccm in the neutralizer. For MgF2 film deposition, the ion source parameters are: voltage 300V, current 300mA, ACC voltage 200V, argon charge 40sccm, and argon charge 8sccm in the neutralizer.

[0072] Step Six: Flip the silicon lens and the substrate over and place them in the coating machine. Repeat steps one through five to coat the same film on the other surface.

[0073] (sub / Ti3O5(168.27nm) / SiO2(225.17nm) / Ti3O5(67.7nm) / SiO2(102.66nm) / Ti3O5(133.3nm) / MgF2(269.23nm) / Air);

[0074] Step 7: After the coating is completed, maintain a constant temperature of 120℃ for 15 minutes, then gradually reduce the temperature to 100℃ and maintain it for 5 minutes, then reduce the temperature to 80℃ and maintain it for 5 minutes, and finally open the door to remove the part when the temperature drops below 70℃.

[0075] After coating, the substrate was subjected to spectral testing, and its low-reflectance spectrum is shown below. Figure 3 As shown, the lens products undergo durability testing.

[0076] Constant temperature and humidity test: After 24 hours of double 85 test, no film peeling or cracking was found on the lens.

[0077] High and low temperature tests: Temperatures ranged from -40℃ to 71℃, with each gradient lasting 2 hours. No film peeling or cracking was observed on any surface of the lens.

[0078] Moderate friction test: The membrane was subjected to 50 cycles of friction with a rubber friction head wrapped with degreased cloth at a pressure of 4.9N, and no scratches or other damage were found.

[0079] Adhesion test: After each test, 3M tape was used to bond each side of the lens. The tape was pulled in the opposite direction to the bonding end, and the film layer was not pulled up.

[0080] Comparative Example 1

[0081] The only difference between this comparative example and Example 1 is that Ta2O5 (tantalum pentoxide) is used instead of Ti3O5 (titanium pentoxide) as the high refractive index material. Everything else remains the same. The final film structure on both sides of the silicon substrate is sub / Ta2O5 (160.79nm) / SiO2 (244.34nm) / Ta2O5 (70.36nm) / SiO2 (56.69nm) / Ta2O5 (161.33nm) / MgF2 (224.41nm) / Air.

[0082] After coating, the coated film was subjected to spectral testing, and the lens product durability was tested. The test results are shown in Table 1.

[0083] Comparative Example 2

[0084] The only difference between this comparative example and Example 1 is that the MgF2 (magnesium fluoride) film material is omitted in both sides of the silicon substrate, and only Ti3O5 and SiO2 film materials are used. The final film structure on both sides of the silicon substrate omits the MgF2 film layer. The specific film structures on both sides of the silicon substrate are as follows:

[0085] sub / Ti3O5(208.84nm) / SiO2(85.94nm) / Ti3O5(182.40nm) / SiO2(121.48nm) / Ti3O5(50nm) / Air.

[0086] After coating, the coated film was subjected to spectral testing, and the lens product durability was tested. The test results are shown in Table 1.

[0087] The low-reflection spectrum of the resulting coated wafer is as follows: Figure 4 As shown; comparison Figure 3 and Figure 4 It can be seen that omitting the MgF2 film layer still results in a low reflectance (high transmittance) effect, but the bandwidth becomes narrower and the transmittance also decreases.

[0088] Comparative Example 3

[0089] The only difference between this comparative example and Example 1 is that the coating temperature is set differently in step two, specifically 160±2℃, while the rest remain the same.

[0090] After coating, the coated film was subjected to spectral testing, and the lens product durability was tested. The test results are shown in Table 1.

[0091] Comparative Example 4

[0092] The only difference between this comparative example and Example 1 is that the pre-plating vacuum setting in step two is different, specifically 5 ± 0.1 × 10⁻⁶. -3 Pa, the rest remain unchanged.

[0093] After coating, the coated film was subjected to spectral testing, and the lens product durability was tested. The test results are shown in Table 1.

[0094] Comparative Example 5

[0095] The only difference between this comparative example and Example 1 is that the ion source parameters are different in step five when depositing the MgF2 film. Specifically, the voltage is 900±2V, the current is 900±2mA, the ACC voltage is 600±2V, the gas filling volume is 40±1sccm of argon, and the neutralizer gas volume is 8sccm of argon. All other parameters remain the same.

[0096] After coating, the coated film was subjected to spectral testing, and the lens product durability was tested. The test results are shown in Table 1.

[0097] The test results of the coated films and lens products prepared in Example 1 and the comparative examples are shown in Table 1. As can be seen from Table 1, the products prepared in the examples have an average reflectance % as low as 0.17% in the 1260~1620nm range, a maximum reflectance as low as 0.20%, and exhibit good adhesion, resistance to constant temperature and humidity, resistance to high and low temperatures, and good resistance to moderate friction.

[0098] Table 1

[0099]

[0100] Example 2

[0101] Step 1: The silicon-based lens and the substrate to be coated are cleaned and polished with alumina polishing solution, followed by ultrasonic cleaning; the coating machine is a Guangchi OTFC1300. The film thickness is entered into the coating file, and parameters such as coating temperature, evaporation rate, coating vacuum, ion source voltage, current, and gas filling amount are set.

[0102] Step 2: Clamp the pre-cleaned product and the substrate to be coated, then place them on the umbrella frame of the coating machine. Close the door and evacuate the air. Set the coating temperature to 115℃; the base vacuum before coating is 1.8×10⁻⁶. -3 Pa; The deposition rate of Ti3O5 film is set to 2.5 Å / s; the deposition rate of SiO2 film is set to 4.5 Å / s; the deposition rate of MgF2 film is set to 4.5 Å / s;

[0103] Step 3: Before coating, pre-melt, degas, and remove impurities from the film material to ensure its purity.

[0104] Step 4: The cavity vacuum level reaches 1.8 × 10⁻⁶. -3 Pa, start the RF source to perform ion cleaning on the lens and the coating, remove the oxide layer and attached particles on the surface of the product and the coating, make the surface cleaner, and increase the adhesion of the film. The cleaning time is 200s, the parameters are voltage 750V, current 750mA, ACC voltage 600V, and gas filling volume of oxygen 70sccm and argon 8sccm.

[0105] Step 5: After the ion source is cleaned, the coating process begins. Vacuum electron beam evaporation is used for coating, and back-reflection light is used to monitor the film thickness, resulting in smaller errors and higher precision compared to crystal monitoring. For Ti3O5 film deposition, the ion source parameters are: voltage 1000V, current 860mA, ACC voltage 570V, oxygen charge 65 sccm, and argon charge 9 sccm in the neutralizer. For SiO2 film deposition, the ion source parameters are: voltage 860V, current 860mA, ACC voltage 570V, oxygen charge 45 sccm, and argon charge 9 sccm in the neutralizer. For MgF2 film deposition, the ion source parameters are: voltage 280V, current 280mA, ACC voltage 180V, argon charge 38 sccm, and argon charge 9 sccm in the neutralizer.

[0106] Step 6: After the coating is completed, maintain a constant temperature of 115℃ for 15 minutes, then gradually lower the temperature to 95℃ and maintain it for 5 minutes, then lower the temperature to 75℃ and maintain it for 5 minutes, and finally open the door to remove the part when the temperature drops below 65℃.

[0107] Step 7: Flip the silicon lens and the substrate over and place them in the coating machine. Repeat steps 1 to 6 to coat the same film on the other surface.

[0108] (sub / Ti3O5(168.27nm) / SiO2(225.17nm) / Ti3O5(67.7nm) / SiO2(102.66nm) / Ti3O5(133.3nm) / MgF2(269.23nm) / Air).

[0109] Durability tests were conducted on the lens products. The results were as follows: Adhesion test: no film detachment; Constant temperature and humidity test: no film detachment; High and low temperature test: no film detachment or cracking; Moderate friction test: no obvious scratches were observed.

[0110] Example 3

[0111] Step 1: The silicon-based lens and the substrate to be coated are cleaned and polished with alumina polishing solution, followed by ultrasonic cleaning; the coating machine is a Guangchi OTFC1300. The film thickness is entered into the coating file, and parameters such as coating temperature, evaporation rate, coating vacuum, ion source voltage, current, and gas filling amount are set.

[0112] Step 2: Clamp the pre-cleaned product and the substrate to be coated, then place them on the umbrella frame of the coating machine. Close the door and evacuate the air. Set the coating temperature to 125℃; the base vacuum before coating is 2.0×10. -3 Pa; The deposition rate of Ti3O5 film is set to 3.5 Å / s; the deposition rate of SiO2 film is set to 5.5 Å / s; the deposition rate of MgF2 film is set to 5.5 Å / s;

[0113] Step 3: Before coating, pre-melt, degas, and remove impurities from the film material to ensure its purity.

[0114] Step 4: The cavity vacuum level reaches 2.0 × 10⁻⁶. -3 Pa, start the RF source to perform ion cleaning on the lens and the coating, remove the oxide layer and attached particles on the surface of the product and the coating, make the surface cleaner, and increase the adhesion of the film. The cleaning time is 200s, the parameters are voltage 750V, current 750mA, ACC voltage 600V, and gas filling volume of oxygen 70sccm and argon 8sccm.

[0115] Step 5: After the ion source is cleaned, the coating process begins. Vacuum electron beam evaporation is used for coating, and back-reflection light is used to monitor the film thickness, resulting in smaller errors and higher precision compared to crystal monitoring. For Ti3O5 film deposition, the ion source parameters are: voltage 1100V, current 940mA, ACC voltage 630V, oxygen charge 75sccm, and argon charge 7sccm in the neutralizer. For SiO2 film deposition, the ion source parameters are: voltage 940V, current 940mA, ACC voltage 630V, oxygen charge 55sccm, and argon charge 7sccm in the neutralizer. For MgF2 film deposition, the ion source parameters are: voltage 320V, current 320mA, ACC voltage 220V, argon charge 42sccm, and argon charge 7sccm in the neutralizer.

[0116] Step 6: After coating is completed, maintain a constant temperature of 125℃ for 15 minutes, then gradually lower the temperature to 105℃ and maintain it for 5 minutes, then lower it to 85℃ and maintain it for 5 minutes, and finally open the door to remove the part when the temperature drops below 75℃.

[0117] Step 7: After flipping the silicon-based lens and the substrate, place them in the coating machine and repeat steps 1 to 6 to deposit the same film layer on the other surface (sub / Ti3O5 (168.27nm) / SiO2 (225.17nm) / Ti3O5 (67.7nm) / SiO2 (102.66nm)).

[0118] / Ti3O5(133.3nm) / MgF2(269.23nm) / Air).

[0119] Durability tests were conducted on the lens products. The results were as follows: Adhesion test: no film detachment; Constant temperature and humidity test: no film detachment; High and low temperature test: no film detachment or cracking; Moderate friction test: no obvious scratches were observed.

[0120] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A near-infrared optical lens, characterized in that, The device includes a silicon substrate and an AR film structure symmetrically disposed on both sides of the silicon substrate. The AR film structure is sub / 0.5(HL)^2(0.5H)K / Air, where H represents a high refractive index layer of one basic thickness, L represents a first low refractive index layer of one basic thickness, and K represents a second low refractive index layer of one basic thickness. The basic thickness corresponding to one H, one L, or one K represents that the film layer has 1 / 4 optical thickness at a reference wavelength. The near-infrared optical lens has an average transmittance of over 90% for light in the wavelength range of 1260~1620nm. The high refractive index layer is a Ti3O5 layer, and the first low refractive index layer is SiO2. The AR film structure comprises a first Ti3O5 layer, a first SiO2 layer, a second Ti3O5 layer, a second SiO2 layer, a third Ti3O5 layer, and a MgF2 layer sequentially disposed on the surface of a silicon substrate; the thickness of the first Ti3O5 layer is 165~170nm, the thickness of the first SiO2 layer is 222~227nm, the thickness of the second Ti3O5 layer is 65~70nm, the thickness of the second SiO2 layer is 100~105nm, the thickness of the third Ti3O5 layer is 130~135nm, and the thickness of the MgF2 layer is 267~272nm.

2. The near-infrared optical lens as described in claim 1, characterized in that, The near-infrared optical lens has an average transmittance of over 95% for light in the wavelength range of 1260~1620nm.

3. The near-infrared optical lens as described in claim 2, characterized in that, The near-infrared optical lens has an average transmittance of over 99% for light in the wavelength range of 1260~1620nm.

4. The near-infrared optical lens as described in claim 1, characterized in that, The thickness of the first Ti3O5 layer is 168.27 nm, the thickness of the first SiO2 layer is 225.17 nm, the thickness of the second Ti3O5 layer is 67.7 nm, the thickness of the second SiO2 layer is 102.66 nm, the thickness of the third Ti3O5 layer is 133.3 nm, and the thickness of the MgF2 layer is 269.23 nm.

5. The method for preparing a near-infrared optical lens according to any one of claims 1 to 4, characterized in that, include: An AR film structure is deposited on the first surface of a silicon substrate. The AR film structure includes a high refractive index layer, a first low refractive index layer, a high refractive index layer, a first low refractive index layer, a high refractive index layer, and a second refractive index layer arranged sequentially. The same AR film structure as the first surface is sequentially deposited on the second surface of the silicon substrate; The near-infrared optical lens is obtained by cooling to room temperature.

6. The method for preparing a near-infrared optical lens as described in claim 5, characterized in that, Before depositing the film layer on the first surface and the film layer on the second surface of the silicon substrate, the following steps are included: placing the silicon substrate in a coating machine and evacuating it to a vacuum of 1.5 × 10⁻⁶. -3 ~2×10 -3 Pa, preheat to 115~125℃, and perform ion source cleaning.

7. The method for preparing a near-infrared optical lens as described in claim 5, characterized in that, The deposition temperature for each film layer is 115~125℃; The deposition rate of each high refractive index layer is 2.5~3.5 Å / s; the deposition rate of each first low refractive index layer is 4.5~5.5 Å / s; and the deposition rate of the second low refractive index layer is 4.5~5.5 Å / s. Each film layer was deposited using vacuum electron beam evaporation coating.

8. The method for preparing a near-infrared optical lens as described in claim 5, characterized in that, The deposition of the second low-refractive-index layer was carried out with the assistance of an RF ion source; the parameters of the RF ion source were: voltage 280~320V, current 280~320mA, ACC voltage 180~220V, gas filling volume of argon 38~42sccm, and neutralizer argon 7~9sccm. Each high refractive index layer was deposited with the assistance of an RF ion source; the parameters of the RF ion source were: voltage 1000~1100V, current 860~940mA, ACC voltage 570~630V, gas filling volume of oxygen 65~75sccm, and neutralizer argon 7~9ssccm. Each first low-refractive-index layer was deposited with the assistance of an RF ion source; the parameters of the RF ion source were: voltage 860~940V, current 860~940mA, ACC voltage 570~630V, gas filling volume of oxygen 45~55sccm, and neutralizer argon 7~9sccm.

9. The method for preparing a near-infrared optical lens as described in claim 5, characterized in that, After the silicon substrate is coated on both sides, it is cooled to below 70°C in stages before being removed.

10. A silicon-based lens for an optical communication wavelength division multiplexing module, characterized in that, This includes near-infrared optical lenses as described in any one of claims 1 to 4, or near-infrared optical lenses prepared by the preparation method described in any one of claims 5 to 9.

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