Near-infrared optical lens and preparation method thereof, and optical communication wavelength division multiplexing module silicon-based lens

Abstract

The invention provides a near-infrared optical lens which comprises a silicon substrate and AR film system structures symmetrically arranged on the two sides of the silicon substrate, the AR film system structures are sub / 0.5 (HL) 2 (0.5 H) K / Air, and the transmittance of the near-infrared optical lens to light within the wavelength range of 1260-1620 nm is 90% or above. 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 at the wavelength of 1260-1620 nm and is far superior to products on the market, and the film layer is good in binding power, moderate friction resistance and constant temperature and humidity resistance and can be applied to a silicon-based lens of an optical communication wavelength division multiplexing module.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical fiber communication, and specifically relates to a design and preparation method for coating a full-band anti-friction, constant temperature and humidity resistant and high-transmittance thin film on a silicon-based lens of an optical fiber communication module in a wavelength range of 1260-1620nm. Background Art

[0002] The working principle of the optical fiber communication system is mainly based on the wavelength multiplexing technology of light, 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 is the process of accurately aligning and combining multiple signals from different light sources through a series of optical components at the transmitting end. The combined signal is then sent to a single optical fiber for transmission. The demultiplexing principle is the opposite of multiplexing. The silicon-based lens in the optical communication module is used for convergence and collimation of the light path, which can effectively reduce energy loss, such as Figure 1 shown.

[0004] However, the silicon-based lenses available on the market cannot significantly reduce energy loss due to their low transmittance (or high reflection value when measuring low reflection), or the film layer is difficult to pass the moderate friction and 48-hour high temperature and high humidity test, which cannot meet the needs of long-term stable operation of optical communications. Summary of the invention In response to the above technical problems, the present application proposes a near-infrared optical lens and a preparation method thereof, and a silicon-based lens for an optical communication wavelength division multiplexing module.

[0005] To achieve the above objectives, this application proposes the following technical solutions: In the first aspect, a near-infrared optical lens is provided, comprising a silicon substrate and an AR film structure symmetrically arranged on both sides of the silicon substrate, wherein the AR film structure is sub / 0.5(HL)^2(0.5H)K / Air, wherein H represents a high refractive index layer of a basic thickness, L represents a first low refractive index layer of a basic thickness, and K represents a second low refractive index layer of a basic thickness, wherein the basic thickness corresponding to 1 H or 1 L or 1 K represents that the film layer has an optical thickness of 1 / 4 at a reference wavelength; the average transmittance of the near-infrared optical lens to light in the wavelength range of 1260~1620nm is above 90%.

[0006] Preferably, the average transmittance of the near-infrared optical lens for light in the wavelength range of 1260~1620nm is above 95%, and more preferably above 99%.

[0007] 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.

[0008] Preferably, 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 which are sequentially arranged 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.

[0009] Preferably, 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.

[0010] In a second aspect, a method for preparing a near-infrared optical lens is provided, comprising: An AR film structure is plated on the first surface of the silicon substrate, wherein the AR film structure comprises 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 in sequence; The same AR film structure as that of the first surface is sequentially plated on the second surface of the silicon substrate; After cooling to room temperature, the near-infrared optical lens is obtained.

[0011] Preferably, before the film layer on the first surface and the film layer on the second surface of the silicon substrate are plated, the process further comprises: placing the silicon substrate in a coating machine and evacuating the vacuum to 1.5×10 -3 ~2×10 -3 Pa, preheat to 115~125℃, and clean the ion source.

[0012] Preferably, the plating temperature of each film layer is 115-125°C.

[0013] Preferably, the deposition rate of each high refractive index layer is 2.5-3.5Å / S; the deposition rate of each first low refractive index layer is 4.5-5.5Å / S; and the deposition rate of the second low refractive index layer is 4.5-5.5Å / S.

[0014] Preferably, each film layer is deposited by vacuum electron beam evaporation.

[0015] Preferably, the second low refractive index layer is deposited with the assistance of an RF ion source; the RF ion source parameters are voltage 280~320V, current 280~320mA, ACC voltage 180~220V, gas filling volume 38~42sccm of argon, and neutralizer argon 7~9sccm.

[0016] Preferably, each high refractive index layer is deposited with the assistance of an RF ion source; the RF ion source parameters are voltage 1000~1100V, current 860~940mA, ACC voltage 570~630V, gas filling volume 65~75sccm of oxygen, and neutralizer argon 7~9ssccm.

[0017] Preferably, each first low refractive index layer is deposited with the assistance of an RF ion source; the RF ion source parameters are voltage 860~940V, current 860~940mA, ACC voltage 570~630V, gas filling volume 45~55sccm of oxygen, and neutralizer argon 7~9sccm.

[0018] Preferably, before placing the silicon substrate into the coating machine, the silicon substrate is polished and cleaned.

[0019] Preferably, back reflection light control is used to monitor film thickness during the coating process.

[0020] Preferably, after the coating on both sides of the silicon substrate is completed, the temperature is step-wise reduced to below 70° C. and then taken out.

[0021] In a third aspect, a silicon-based lens for an optical communication wavelength division multiplexing module is provided, comprising the aforementioned near-infrared optical lens or a near-infrared optical lens prepared by the aforementioned preparation method.

[0022] Compared with the prior art, one or more of the above technical solutions can achieve at least one of the following beneficial effects: The provided near-infrared optical lens includes a silicon substrate and an AR film structure symmetrically arranged on both sides of the silicon substrate. Through the matching design of film materials, film structure and thickness, the near-infrared optical lens exhibits the advantages of low reflection and high transmittance at a wavelength of 1260~1620nm, which is far superior to products on the market. The film layer has good adhesion, resistance to moderate friction, and good resistance to constant temperature and humidity, and can be applied to silicon-based lenses in optical communication wavelength division multiplexing modules.

[0023] The provided method for preparing the near-infrared optical lens is beneficial to further improving the adhesion, moderate friction resistance and constant temperature and humidity resistance of the film system by optimizing the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 Schematic diagram of the silicon-based lens in the optical communication module.

[0026] Figure 2 This is a low-reflection spectrum diagram of the silicon substrate film system designed in Example 1.

[0027] Figure 3 This is a low-reflection spectrum diagram of the accompanying plating sheet obtained in Example 1.

[0028] Figure 4 This is the low-reflection spectrum of the accompanying plating sheet obtained in Comparative Example 2.

[0029] Wherein, the accompanying drawings are marked as follows: 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

[0030] The present invention provides a near-infrared optical lens, comprising a silicon substrate and an AR film structure symmetrically arranged on both sides of the silicon substrate, wherein the AR film structure is sub / 0.5(HL)^2(0.5H)K / Air, that is, sub / (0.5H0.5L)^2(0.5H)K / Air, wherein H represents a high refractive index layer of a basic thickness, L represents a first low refractive index layer of a basic thickness, and K represents a second low refractive index layer of a basic thickness, wherein the basic thickness corresponding to 1 H or 1 L or 1 K represents that the film layer has an optical thickness of 1 / 4 at a reference wavelength; the average transmittance of the near-infrared optical lens to light in the wavelength range of 1260~1620nm is above 90%.

[0031] In some preferred embodiments, the average transmittance of the near-infrared optical lens for light in the wavelength range of 1260~1620nm 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.

[0032] 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.

[0033] 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 arranged 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.

[0034] 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.

[0035] In some embodiments, the average reflectivity of the silicon-based anti-reflection film at a wavelength of 1260-1620 μm can be as low as 0.17%, and the maximum reflectivity at a wavelength of 1260-1620 μm can be as low as 0.20%.

[0036] The present invention provides a method for preparing a near-infrared optical lens, comprising: An AR film structure is plated on the first surface of the silicon substrate, wherein the AR film structure comprises 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 in sequence; The same AR film structure as that of the first surface is sequentially plated on the second surface of the silicon substrate; After cooling to room temperature, the near-infrared optical lens is obtained.

[0037] In some preferred embodiments, before the film layer on the first surface and the film layer on the second surface of the silicon substrate are plated, the process further includes: placing the silicon substrate in a coating machine and evacuating the vacuum to 1.5×10 -3 ~2×10 -3 Pa, preheat to 115~125℃, and clean the ion source.

[0038] Before cleaning the ion source, the film material is pre-melted, degassed and impurities removed to ensure the purity of the film material.

[0039] Ion source ion cleaning can remove the oxide layer and attached particles on the surface of the product and the accompanying plated sheet, making the surface cleaner and increasing the adhesion of the film layer. The ion source can use an RF radio frequency source, and the parameters can be voltage 750±2V, current 750±2mA, ACC voltage 600±2V, and the gas filling volume is 70±1sccm for oxygen and 8sccm for argon.

[0040] In some preferred embodiments, the plating temperature of each film layer is 115-125°C.

[0041] In some preferred embodiments, the deposition rate of each high refractive index layer is 2.5-3.5Å / S; the deposition rate of each first low refractive index layer is 4.5-5.5Å / S; and the deposition rate of the second low refractive index layer is 4.5-5.5Å / S.

[0042] In some preferred embodiments, the second low refractive index layer is deposited with the assistance of an RF ion source; the RF ion source parameters are voltage 280~320V, current 280~320mA, ACC voltage 180~220V, gas filling volume 38~42sccm of argon, and neutralizer argon 7~9sccm.

[0043] In some preferred embodiments, each high refractive index layer is deposited with the assistance of an RF ion source; the RF ion source parameters are voltage 1000-1100V, current 860-940mA, ACC voltage 570-630V, gas filling volume 65-75sccm of oxygen, and neutralizer argon 7-9ssccm; In some preferred embodiments, each first low refractive index layer is deposited with the assistance of an RF ion source; the RF ion source parameters are voltage 860~940V, current 860~940mA, ACC voltage 570~630V, gas filling volume 45~55sccm of oxygen, and neutralizer argon 7~9sccm.

[0044] In some preferred embodiments, before the silicon substrate is placed in the coating machine, the silicon substrate is polished and cleaned. Back reflection light control is used to monitor the film thickness during the coating process.

[0045] In some preferred embodiments, after the coating on both sides of the silicon substrate is completed, the temperature is stepped down to below 70°C before being taken out. Further preferably, after the coating is completed, the temperature is kept at 115-125°C for 15 minutes and then stepped down to below 65-75°C before being taken out. Preferably, the step-by-step cooling is: firstly cooling down to 95-105°C for 5 minutes, then cooling down to 75-85°C for 5 minutes, and finally cooling down to below 65-75°C before opening the door to take out the parts.

[0046] 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.

[0047] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments.

[0048] Example 1 The implementation process of the method for preparing the silicon-based lens film disclosed this time is as follows: Film system design: The film system design uses 550nm as the central wavelength of the optical 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 D0.5±0.05mm*1±0.05mmlens, and the accompanying coating film is a 25±0.1mm*3±0.1mm wedge-shaped film. Air represents air. In the film stack expression: L represents a low refractive index material SiO2 (silicon dioxide) with a thickness of 1 / 4 wavelength.

[0049] H represents low-refractive-index Ti3O5 (titanium pentoxide) with a thickness of 1 / 4 wavelength.

[0050] K represents the low refractive index material MgF2 (magnesium fluoride) with a thickness of 1 / 4 wavelength.

[0051] Finally, it was determined that the film stack on both surfaces of the silicon substrate was sub / 0.5(HL)^2(0.5H) K / Air, and the film thickness was: sub / Ti3O5(168.27nm) / SiO2(225.17nm) / Ti3O5(67.7nm) / SiO2(102.66nm) / Ti3O5(133.3nm) / MgF2(269.23nm) / Air; the low reflection spectrum of the designed film is shown in Figure 2 shown.

[0052] Step 1: The silicon-based lens and the accompanying plate are cleaned and polished with alumina polishing liquid, and then cleaned with ultrasonic wave. The coating machine is Guangchi OTFC1300. The film thickness is input into the coating file, and the coating temperature, evaporation rate, coating vacuum, ion source voltage, current, and gas volume are set.

[0053] Step 2: Clamp the pre-cleaned product and the accompanying plating sheet, then put them into the umbrella stand of the coating machine, close the door and exhaust, set the coating temperature to 120℃; the background vacuum before plating is 1.5×10 -3Pa; set the Ti3O5 film deposition rate to 3Å / S; the SiO2 film deposition rate to 5Å / S; the MgF2 film deposition rate to 5Å / S; Step 3: Before coating, pre-melt the film material to release air and remove impurities to ensure the purity of the film material.

[0054] Step 4: The vacuum degree of the chamber reaches 1.5×10 -3 Pa, start the RF source to ion clean the lens and the accompanying plating sheet to remove the oxide layer and attached particles on the surface of the product and the accompanying plating sheet, make the surface cleaner, and increase the adhesion of the film layer. The cleaning time is 200s, the parameters are voltage 750V, current 750mA, ACC voltage 600V, and the inflation volume is 70sccm for oxygen and 8sccm for argon.

[0055] Step 5: After the ion source is cleaned, the coating process is called to start coating. The coating adopts vacuum electron beam evaporation coating, and the film thickness is monitored by back reflection light control. The error is smaller than crystal monitoring and the accuracy is higher. When depositing the Ti3O5 film, the ion source parameters are voltage 1050V, current 900mA, ACC voltage 600V, gas filling volume 70sccm of oxygen, and neutralizer argon 8sccm; when depositing the SiO2 film, the ion source parameters are voltage 900V, current 900mA, ACC voltage 600V, gas filling volume 50sccm of oxygen, and neutralizer argon 8sccm; when depositing the MgF2 film, the ion source parameters are voltage 300V, current 300mA, ACC voltage 200V, gas filling volume 40sccm of argon, and neutralizer argon 8sccm.

[0056] Step 6: Turn over the silicon-based lens and the accompanying coating film and place them in the coating machine. Repeat steps 1 to 5 to coat the same film layer on the other surface. (sub / Ti3O5(168.27nm) / SiO2(225.17nm) / Ti3O5(67.7nm) / SiO2(102.66nm) / Ti3O5(133.3nm) / MgF2(269.23nm) / Air); Step 7: After the coating is completed, it is necessary to maintain a constant temperature of 120℃ for 15 minutes, then step-down to 100℃ for 5 minutes, then to 80℃ for 5 minutes, and open the door to take out the parts when the temperature drops below 70℃.

[0057] After coating, the accompanying plated film is tested for spectrum, and its low-reflection spectrum is as follows Figure 3 As shown, lens products undergo durability testing.

[0058] Constant temperature and humidity test: Double 85 test for 24 hours, no film peeling or cracking on the lens was found.

[0059] High and low temperature test: temperature from -40℃ to 71℃, 2 hours per gradient. No film peeling or cracking was found on the lens surface.

[0060] Moderate friction test: The film layer was rubbed 50 times with a rubber friction head wrapped with degreased cloth at a pressure of 4.9N, and no scratches or other damage were found.

[0061] Adhesion test: After each experiment, the lens was bonded with 3M tape on each side and the tape was pulled in the opposite direction of the end face and the adhesive end, but the film layer was not pulled up.

[0062] Comparative Example 1 The difference between this comparative example and Example 1 is that the film material Ta2O5 (tantalum pentoxide) is used instead of the film material Ti3O5 (titanium pentoxide) as the high refractive index material, and the rest remains unchanged. The final film layer 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.

[0063] After coating, the accompanying plated film was subjected to spectrum test and the lens product durability test. The test results are shown in Table 1.

[0064] Comparative Example 2 The difference between this comparative example and Example 1 is that the MgF2 (magnesium fluoride) film material is omitted in the film layers on both sides of the silicon substrate, and only two film materials, Ti3O5 and SiO2, are used. The MgF2 film layer is omitted in the final film layer structure on both sides of the silicon substrate. The film layer structure on both sides of the silicon substrate is specifically as follows: sub / Ti3O5(208.84nm) / SiO2(85.94nm) / Ti3O5(182.40nm) / SiO2(121.48nm) / Ti3O5(50nm) / Air.

[0065] After coating, the accompanying plated film was subjected to spectrum test and the lens product durability test. The test results are shown in Table 1.

[0066] The low-reflection spectrum of the obtained accompanying plating sheet is as follows: Figure 4 shown; contrast Figure 3 and Figure 4 It can be seen that after omitting the MgF2 film layer, it still has a low reflection (high transmittance) effect, but the bandwidth becomes narrower and the transmittance is also reduced.

[0067] Comparative Example 3 The difference between this comparative example and Example 1 is that in step 2, the coating temperature is set differently, specifically 160±2° C., and the rest remains unchanged.

[0068] After coating, the accompanying plated film was subjected to spectrum test and the lens product durability test. The test results are shown in Table 1.

[0069] Comparative Example 4 The difference between this comparative example and Example 1 is that in step 2, the background vacuum setting before plating is different, specifically 5±0.1×10 -3 Pa, and the rest remain unchanged.

[0070] After coating, the accompanying plated film was subjected to spectrum test and the lens product durability test. The test results are shown in Table 1.

[0071] Comparative Example 5 The difference between this comparative example and Example 1 is that in step five, the ion source parameters are different when depositing the MgF2 film, specifically, the voltage is 900±2V, the current is 900±2mA, the ACC voltage is 600±2V, the filling volume is 40±1sccm of argon, the neutralizer argon is 8sccm, and the rest remains unchanged.

[0072] After coating, the accompanying plated film was subjected to spectrum test and the lens product durability test. The test results are shown in Table 1.

[0073] The test results of the accompanying plating sheets and lens products prepared in Example 1 and the comparative examples are shown in Table 1. As can be seen from Table 1, the average reflectivity of the product prepared in the example can be as low as 0.17% at 1260-1620nm, the maximum reflectivity is as low as 0.20%, and it has good adhesion, constant temperature and humidity resistance, high and low temperature resistance and good medium friction resistance.

[0074] Table 1 Example 2 Step 1: The silicon-based lens and the accompanying plate are cleaned and polished with alumina polishing liquid, and then cleaned with ultrasonic wave. The coating machine is Guangchi OTFC1300. The film thickness is input into the coating file, and the coating temperature, evaporation rate, coating vacuum, ion source voltage, current, and gas volume are set.

[0075] Step 2: Clamp the pre-cleaned product and the accompanying plating sheet, then put them on the umbrella stand of the coating machine, close the door and evacuate the air, set the coating temperature to 115℃; the background vacuum before plating is 1.8×10 -3 Pa; set the Ti3O5 film deposition rate to 2.5Å / S; the SiO2 film deposition rate to 4.5Å / S; the MgF2 film deposition rate to 4.5Å / S; Step 3: Before coating, pre-melt the film material to release air and remove impurities to ensure the purity of the film material.

[0076] Step 4: The vacuum degree of the chamber reaches 1.8×10-3 Pa, start the RF source to ion clean the lens and the accompanying plating sheet to remove the oxide layer and attached particles on the surface of the product and the accompanying plating sheet, make the surface cleaner, and increase the adhesion of the film layer. The cleaning time is 200s, the parameters are voltage 750V, current 750mA, ACC voltage 600V, and the inflation volume is 70sccm for oxygen and 8sccm for argon.

[0077] Step 5: After the ion source is cleaned, the coating process is called to start coating. The coating adopts vacuum electron beam evaporation coating, and the film thickness is monitored by back reflection light control. The error is smaller than that of crystal monitoring and the accuracy is higher. When depositing the Ti3O5 film, the ion source parameters are voltage 1000V, current 860mA, ACC voltage 570V, gas filling volume 65sccm of oxygen, and neutralizer argon 9sccm; when depositing the SiO2 film, the ion source parameters are voltage 860V, current 860mA, ACC voltage 570V, gas filling volume 45sccm of oxygen, and neutralizer argon 9sccm; when depositing the MgF2 film, the ion source parameters are voltage 280V, current 280mA, ACC voltage 180V, gas filling volume 38sccm of argon, and neutralizer argon 9sccm.

[0078] Step 6: After the coating is completed, it is necessary to maintain a constant temperature of 115℃ for 15 minutes, then step-down to 95℃ for 5 minutes, then to 75℃ for 5 minutes, and then open the door to take out the parts when the temperature drops below 65℃.

[0079] Step 7: Turn over the silicon-based lens and the accompanying coating film and place them in the coating machine. Repeat steps 1 to 6 to coat the same film layer on the other surface. (sub / Ti3O5(168.27nm) / SiO2(225.17nm) / Ti3O5(67.7nm) / SiO2(102.66nm) / Ti3O5(133.3nm) / MgF2(269.23nm) / Air).

[0080] The lens product durability test, the test results are as follows: Adhesion test: the film layer did not peel off, constant temperature and humidity test: the film layer did not peel off; high and low temperature test: the film layer did not peel off or crack; moderate friction test: no obvious scratches were found.

[0081] Example 3 Step 1: The silicon-based lens and the accompanying plate are cleaned and polished with alumina polishing liquid, and then cleaned with ultrasonic wave. The coating machine is Guangchi OTFC1300. The film thickness is input into the coating file, and the coating temperature, evaporation rate, coating vacuum, ion source voltage, current, and gas volume are set.

[0082] Step 2: Clamp the pre-cleaned product and the accompanying plating sheet, then put them on the umbrella stand of the coating machine, close the door and evacuate the air, set the coating temperature to 125℃; the background vacuum before plating is 2.0×10 -3 Pa; set the Ti3O5 film deposition rate to 3.5Å / S; the SiO2 film deposition rate to 5.5Å / S; the MgF2 film deposition rate to 5.5Å / S; Step 3: Before coating, pre-melt the film material to release air and remove impurities to ensure the purity of the film material.

[0083] Step 4: The vacuum degree of the chamber reaches 2.0×10 -3 Pa, start the RF source to ion clean the lens and the accompanying plating sheet to remove the oxide layer and attached particles on the surface of the product and the accompanying plating sheet, make the surface cleaner, and increase the adhesion of the film layer. The cleaning time is 200s, the parameters are voltage 750V, current 750mA, ACC voltage 600V, and the inflation volume is 70sccm for oxygen and 8sccm for argon.

[0084] Step 5: After the ion source is cleaned, the coating process is called to start coating. The coating adopts vacuum electron beam evaporation coating, and the film thickness is monitored by back reflection light control. The error is smaller than crystal monitoring and the accuracy is higher. When depositing Ti3O5 film, the ion source parameters are voltage 1100V, current 940mA, ACC voltage 630V, gas filling volume 75sccm of oxygen, and neutralizer argon 7sccm; when depositing SiO2 film, the ion source parameters are voltage 940V, current 940mA, ACC voltage 630V, gas filling volume 55sccm of oxygen, and neutralizer argon 7sccm; when depositing MgF2 film, the ion source parameters are voltage 320V, current 320mA, ACC voltage 220V, gas filling volume 42sccm of argon, and neutralizer argon 7sccm.

[0085] Step 6: After the coating is completed, it is necessary to maintain a constant temperature of 125℃ for 15 minutes, then step-down to 105℃ for 5 minutes, then to 85℃ for 5 minutes, and then open the door to take out the parts when the temperature drops below 75℃.

[0086] Step 7: Turn over the silicon-based lens and the accompanying coating film and place them in the coating machine. Repeat steps 1 to 6 to coat the same film layer on the other surface (sub / Ti3O5 (168.27nm) / SiO2 (225.17nm) / Ti3O5 (67.7nm) / SiO2 (102.66nm) / Ti3O5(133.3nm) / MgF2(269.23nm) / Air).

[0087] The lens product durability test, the test results are as follows: Adhesion test: the film layer did not peel off, constant temperature and humidity test: the film layer did not peel off; high and low temperature test: the film layer did not peel off or crack; moderate friction test: no obvious scratches were found.

[0088] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A near-infrared optical lens, characterized in that: It includes a silicon substrate and an AR film structure symmetrically arranged on both sides of the silicon substrate, wherein the AR film structure is sub / 0.5(HL)^2(0.5H)K / Air, wherein H represents a high refractive index layer of a basic thickness, L represents a first low refractive index layer of a basic thickness, and K represents a second low refractive index layer of a basic thickness, wherein the basic thickness corresponding to 1 H or 1 L or 1 K represents that the film layer has an optical thickness of 1 / 4 at a reference wavelength; the average transmittance of the near-infrared optical lens to light in the wavelength range of 1260~1620nm is above 90%.

2. The near-infrared optical lens according to claim 1, characterized in that: The average transmittance of the near-infrared optical lens to light in the wavelength range of 1260-1620 nm is 95% or more, preferably 99% or more; 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.

3. The near-infrared optical lens according to claim 2, characterized in that: 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 which are sequentially arranged 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.

4. The near-infrared optical lens according to claim 3, 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 plated on the first surface of the silicon substrate, wherein the AR film structure comprises 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 in sequence; The same AR film structure as that of the first surface is sequentially plated on the second surface of the silicon substrate; After cooling to room temperature, the near-infrared optical lens is obtained.

6. The method for preparing the near-infrared optical lens according to claim 5, characterized in that: Before the film layer on the first surface and the film layer on the second surface of the silicon substrate are plated, the process includes: placing the silicon substrate in a coating machine, evacuating the vacuum to 1.5×10 -3 ~2×10 -3 Pa, preheat to 115~125℃, and clean the ion source.

7. The method for preparing the near-infrared optical lens according to claim 2, characterized in that: The plating temperature of each film layer is 115~125℃; The deposition rate of each high refractive index layer is 2.5~3.5Å / S; the deposition rate of each first low refractive index layer is 4.5~5.5Å / S; the deposition rate of the second low refractive index layer is 4.5~5.5Å / S; The coating method of each film layer is vacuum electron beam evaporation coating.

8. The method for preparing the near-infrared optical lens according to claim 2, characterized in that: The second low refractive index layer is deposited with the assistance of an RF ion source; the RF ion source parameters are voltage 280-320V, current 280-320mA, ACC voltage 180-220V, gas filling volume 38-42sccm of argon, and neutralizer argon 7-9sccm; Each high refractive index layer is deposited with the assistance of an RF ion source; the RF ion source parameters are voltage 1000-1100V, current 860-940mA, ACC voltage 570-630V, gas filling volume 65-75sccm of oxygen, and neutralizer argon 7-9ssccm; Each first low refractive index layer is deposited with the assistance of an RF ion source; the RF ion source parameters are voltage 860-940V, current 860-940mA, ACC voltage 570-630V, gas filling volume 45-55sccm of oxygen, and neutralizer argon 7-9sccm.

9. The method for preparing the near-infrared optical lens according to claim 2, characterized in that: After the coating on both sides of the silicon substrate is completed, the temperature is step-wise reduced to below 70° C. and then taken out.

10. Optical communication wavelength division multiplexing module silicon-based lens, characterized in that: Including the near-infrared optical lens as described in any one of claims 1 to 4 or the near-infrared optical lens prepared by the preparation method as described in any one of claims 5 to 9.

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