Nonlinear optical CLBO crystal anti-reflection moisture-proof protective film and preparation method thereof

Abstract

The present application relates to the technical field of optical film, in particular to a kind of nonlinear optical CLBO crystal antifouling moisture-proof protective film and preparation method thereof.The preparation method comprises the following steps: using sol-gel method to prepare high refractive index HfO2 Film and low refractive index SiO2 Film layer, and it is matched heat treatment to be made into the antifouling moisture-proof protective film of CLBO crystal.The present application uses sol-gel pulling method to coat HfO2 / SiO2 Deep ultraviolet antifouling moisture-proof protective film, and preparation method is simple, that is, using sol-gel method to prepare higher refractive index and laser damage threshold HfO2 Film, and low refractive index SiO2 Film layer is matched to be made into antifouling film.Air moisture molecules can be isolated from contact with crystal, avoid the erosion of water molecules to crystal and deliquescence reaction, while it can increase the transmittance of crystal element, greatly reduce laser loss, improve the performance of crystal laser.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical film technology, in particular to a nonlinear optical CLBO crystal anti-fogging and anti-reflection protective film and a preparation method thereof. BACKGROUND

[0002] Cesium lithium borate (CsLiB6O 10 , abbreviated as CLBO) crystal is a very important new nonlinear optical crystal, and has a light transmission range of 180-2750nm. The CLBO crystal can be used for obtaining 266nm by four times frequency multiplication (FHG) of a neodymium laser, 213nm by five times frequency multiplication (5HG), and 193nm vacuum ultraviolet wavelength by difference frequency (SFG). The CLBO crystal has a high laser damage threshold, a small walk-off angle, a large acceptance angle, a large temperature bandwidth and a large spectral bandwidth, and has a wide application prospect in the field of high-power ultraviolet and deep ultraviolet solid-state lasers.

[0003] The CLBO crystal has excellent ultraviolet nonlinear characteristics, but the CLBO crystal will absorb water molecules in the air at room temperature and be deliquescent and cracked, which restricts the popularization and application of the CLBO crystal. Foreign researchers have proposed a method for solving the deliquescence of the CLBO crystal, i.e. a hot field isolation water vapor technology. The CLBO crystal element is placed in a temperature-controlled moisture-proof box with a temperature of about 100-160℃. The temperature-controlled box is used for moisture-proofing, and the crystal device needs to be continuously and uninterruptedly heated for protection to isolate the water molecules from the CLBO crystal element. The use is inconvenient and the energy consumption is high. The use is limited by power supply, structure weight, application environment and other factors. The transmittance of the CLBO element cannot be improved, and repeated heating and cooling during use also affects the optical quality of the crystal.

[0004] Chinese patent CN103757706A discloses a preparation method of a nonlinear optical crystal surface anti-fogging and anti-reflection protective film. The method is aimed at the deliquescent nonlinear optical crystal, and provides a double-layer anti-fogging and anti-reflection protective film preparation method from the sol characteristics and the film structure. However, the preparation method is complicated, and two steps are required, i.e. plating a moisture-proof film on the crystal and then plating a modified anti-reflection film. SUMMARY

[0005] In view of the above problems in the prior art, the present application aims to provide a compact nonlinear optical CLBO crystal anti-fogging and anti-reflection protective film with high laser damage resistance, which can greatly prolong the service life of the crystal element and improve the laser performance of the crystal.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] In one aspect, the application provides a method for preparing a non-linear optical CLBO crystal anti-moisture and anti-reflection protective film, which comprises the following steps: preparing a high-refractive HfO2 film and a low-refractive SiO2 film layer by a sol-gel method, and matching heat treatment to prepare the anti-moisture and anti-reflection protective film of the CLBO crystal.

[0008] Further, the high-refractive HfO2 film is prepared by using organic alcohol salt hafnium n-propyl alcohol as a precursor.

[0009] Further, the low-refractive SiO2 film layer is prepared by using tetraethyl orthosilicate.

[0010] Further, the method for preparing the hafnium n-propyl alcohol sol comprises the following steps:

[0011] Dissolve acetylacetone with a purity of 99.9% or above in anhydrous ethanol to prepare a solution A with a mass concentration of 5-20 wt%; dissolve hafnium n-propyl alcohol with a purity of 99.9% or above in anhydrous ethanol to prepare a solution B with a mass concentration of 5-20 wt%;

[0012] Under the condition of vigorous stirring, drop the solution A into the solution B drop by drop, then add hydrochloric acid with a mass concentration of 0.1-0.2 wt% to adjust the PH value to 3-5, and stir at 40-60°C for 1-5 hours to obtain hafnium n-propyl alcohol sol with a mass concentration of 3-8 wt%.

[0013] Further, the method for preparing the tetraethyl orthosilicate sol comprises the following steps:

[0014] Dissolve tetraethyl orthosilicate with a purity of 99.9% or above in anhydrous ethanol to prepare a solution C with a mass concentration of 3-20 wt%, then add hydrochloric acid with a mass concentration of 0.1-0.2 wt% to adjust the PH value to 2-5, and stir at 50-80°C for 8-24 hours to obtain tetraethyl orthosilicate sol with a mass concentration of 2-9 wt%.

[0015] Further, the hafnium n-propyl alcohol sol and the tetraethyl orthosilicate sol are uniformly coated on the surface of the CLBO crystal by a pulling method according to a ratio of 3-7 wt%.

[0016] Further, the CLBO crystal with the anti-moisture and anti-reflection protective film is heat treated at 150-200°C for 4-10 hours to form a dense HfO2 / SiO2 protective film layer.

[0017] Another application provides a non-linear optical CLBO crystal anti-moisture and anti-reflection protective film, which is a HfO2 / SiO2 deep ultraviolet anti-moisture and anti-reflection protective film.

[0018] The application has the following advantages:

[0019] The application adopts sol-gel pulling method to coat HfO2 / SiO2 deep ultraviolet antifogging and moisture-proof protective film, and the preparation method is simple, that is, the sol-gel method is used to prepare HfO2 film with high refractive index and laser damage threshold, and the low refractive index SiO2 film layer is matched to prepare the antireflection film. The moisture in the air can be isolated from the contact with the crystal, the moisture can be prevented from eroding the crystal and causing deliquescence reaction, meanwhile, the transmittance of the crystal element can be increased, the laser loss can be greatly reduced, and the crystal laser performance can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The transmittance at 210nm of the CLBO crystal and the coated film in example 3 and example 4 is measured and compared;

[0021] Figure 2 The transmittance at 263nm of the CLBO crystal and the coated film in example 3 and example 4 is measured and compared;

[0022] Figure 3 The transmittance at 1053nm of the CLBO crystal and the coated film in example 3 and example 4 is measured and compared;

[0023] Figure 4 The CLBO crystal coated with HfO2 / SiO2 protective film in example 3 and example 4 is placed in the ordinary atmospheric environment for 4 months. DETAILED DESCRIPTION

[0024] The specific embodiments of the application are described below to facilitate the understanding of the application by those skilled in the art, but it should be clear that the application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the application defined and determined by the appended claims, and all the application and creation utilizing the concept of the application are within the scope of protection.

[0025] Example 1

[0026] Dissolve acetylacetone with a purity of 99.9% in anhydrous ethanol (superior pure), and prepare solution A with a mass concentration of 5wt%; dissolve hafnium n-propyl alcohol with a purity of 99.9% in anhydrous ethanol (superior pure), and prepare solution B with a mass concentration of 10wt%; drop solution A into solution B drop by drop, then add hydrochloric acid with a mass concentration of 0.1wt% to adjust PH=3, and stir at 40℃ for 4 hours to obtain hafnium n-propyl alcohol sol with a mass concentration of 4wt%.

[0027] Dissolve tetraethyl orthosilicate with purity of 99.9% in anhydrous ethanol (superior pure) to prepare a solution C with a mass concentration of 5wt%; then add hydrochloric acid with a mass concentration of 0.15wt% to adjust PH=2; stir at 50°C for 8 hours to obtain a tetraethyl orthosilicate sol with a mass concentration of 3wt%.

[0028] Synthetic hafnium n-propylate sol and tetraethyl orthosilicate sol are uniformly coated on the surface of CLBO crystal to be protected by dip-coating method at a ratio of 3wt% of hafnium n-propylate sol to tetraethyl orthosilicate sol to form a moisture-proof and anti-hygroscopic protective film.

[0029] The CLBO crystal coated with the moisture-proof and anti-hygroscopic protective film is heat-treated at 150°C for 8 hours to form a dense HfO2 / SiO2 protective film layer.

[0030] Drop water on the CLBO crystal coated with the HfO2 / SiO2 protective film by using a pipette and place it for 4 hours, and no deliquescence of the crystal is observed.

[0031] Example 2

[0032] Dissolve acetylacetone with purity of 99.9% in anhydrous ethanol (superior pure) to prepare a solution A with a mass concentration of 10wt%; dissolve hafnium n-propylate with purity of 99.9% in anhydrous ethanol (superior pure) to prepare a solution B with a mass concentration of 10wt%; drop solution A into solution B drop by drop, then add hydrochloric acid with a mass concentration of 0.2wt% to adjust PH=5; stir at 60°C for 2 hours to obtain a hafnium n-propylate sol with a mass concentration of 3wt%.

[0033] Dissolve tetraethyl orthosilicate with purity of 99.9% in anhydrous ethanol (superior pure) to prepare a solution C with a mass concentration of 15wt%; then add hydrochloric acid with a mass concentration of 0.15wt% to adjust PH=3; stir at 80°C for 12 hours to obtain a tetraethyl orthosilicate sol with a mass concentration of 6wt%.

[0034] Synthetic hafnium n-propylate sol and tetraethyl orthosilicate sol are uniformly coated on the surface of CLBO crystal to be protected by dip-coating method at a ratio of 5wt% of hafnium n-propylate sol to tetraethyl orthosilicate sol to form a moisture-proof and anti-hygroscopic protective film.

[0035] The CLBO crystal coated with the moisture-proof and anti-hygroscopic protective film is heat-treated at 200°C for 4 hours to form a dense HfO2 / SiO2 protective film layer.

[0036] The CLBO crystal coated with the HfO2 / SiO2 protective film is placed in a constant temperature and humidity chamber with a temperature of 25°C and a relative humidity of 90% for 2 months, and no deliquescence is observed.

[0037] Example 3

[0038] Dissolve acetylacetone with purity of 99.9% in anhydrous ethanol (extra pure) to form solution A with mass concentration of 20wt%; dissolve hafnium n-propoxide with purity of 99.9% in anhydrous ethanol (extra pure) to form solution B with mass concentration of 15wt%; under the condition of vigorous stirring, drop solution A into solution B, then add hydrochloric acid with mass concentration of 0.2wt% to adjust PH=5, stir for 5 hours at 60℃ to obtain hafnium n-propoxide sol with mass concentration of 8wt%.

[0039] Dissolve tetraethyl orthosilicate with purity of 99.9% in anhydrous ethanol (extra pure) to form solution C with mass concentration of 20wt%, then add hydrochloric acid with mass concentration of 0.2wt% to adjust PH=5, stir for 24 hours at 80℃ to obtain tetraethyl orthosilicate sol with mass concentration of 9wt%.

[0040] Synthetic hafnium n-propoxide sol and tetraethyl orthosilicate sol are uniformly coated on the surface of CLBO crystal to be protected by dip-coating method with the ratio of hafnium n-propoxide sol: tetraethyl orthosilicate sol being 7wt%.

[0041] The CLBO crystal coated with moisture-proof and anti-hygroscopic protective film is heat-treated at 200℃ for 8 hours to form a dense HfO2 / SiO2 protective film layer.

[0042] The CLBO crystal coated with HfO2 / SiO2 protective film is placed in a normal atmospheric environment, and no deliquescence is observed for 4 months. The transmittance of the crystal element is increased by 4.29%, 7.08% and 2.19% at 210nm, 263nm and 1053nm respectively, indicating that the HfO2 / SiO2 film can isolate water molecules in the air from contacting the crystal, prevent deliquescence, increase transmittance, reduce laser loss, and improve the laser performance of four-fold and five-fold frequency of the crystal.

[0043] Example 4

[0044] Dissolve acetylacetone with purity of 99.9% in anhydrous ethanol (extra pure) to form solution A with mass concentration of 15wt%; dissolve hafnium n-propoxide with purity of 99.9% in anhydrous ethanol (extra pure) to form solution B with mass concentration of 20wt%; under the condition of vigorous stirring, drop solution A into solution B, then add hydrochloric acid with mass concentration of 0.2wt% to adjust PH=3, stir for 5 hours at 50℃ to obtain hafnium n-propoxide sol with mass concentration of 3wt%.

[0045] Dissolve tetraethyl orthosilicate with purity of 99.9% in anhydrous ethanol (superior pure) to prepare a solution C with a mass concentration of 10 wt%, then add hydrochloric acid with a mass concentration of 0.2 wt%, adjust PH to 4, and obtain a tetraethyl orthosilicate sol with a mass concentration of 7.5 wt% by stirring at 80℃ for 24 hours.

[0046] Synthetic n-propyl hafnium sol and tetraethyl orthosilicate sol are uniformly coated on the surface of CLBO crystal to be protected by dip-coating method in a ratio of 6 wt% of n-propyl hafnium sol to tetraethyl orthosilicate sol to form a moisture-proof and anti-hygroscopic protective film.

[0047] The CLBO crystal coated with the moisture-proof and anti-hygroscopic protective film is heat-treated at 160℃ for 10 hours to form a dense HfO2 / SiO2 protective film layer.

[0048] The CLBO crystal coated with the HfO2 / SiO2 protective film is placed in a normal atmospheric environment, and no deliquescence is observed for 4 months, and the transmittance of the crystal element is increased by 4.31%, 7.07% and 2.18% at 210 nm, 263 nm and 1053 nm, respectively, indicating that the HfO2 / SiO2 film can isolate the contact between water molecules in the air and the crystal, prevent deliquescence, increase the transmittance, reduce laser loss, and improve the laser performance of the four-fold and five-fold frequency of the crystal.

[0049] In summary, the HfO2 / SiO2 moisture-proof and anti-hygroscopic protective film coated on the light-transmitting surface and non-light-transmitting surface of the CLBO crystal can isolate the contact between water molecules in the air and the crystal in a normal atmospheric environment, avoid the deliquescence and cracking of the crystal, and lose the nonlinear optical frequency conversion function of the crystal, and can be saved and normally used in a normal atmospheric environment, increase the transmittance of the crystal (see Table 1), and improve the laser performance of the crystal, which has a wide application prospect in high-power ultraviolet and deep ultraviolet laser technology. Figures 1-3

[0050] Table 1 Comparison of actual transmittance of CLBO crystal and coated film

[0051] Wavelength (nm) 210 263 1053 Crystal transmittance (%) 88.12 91.54 93.56 Coated crystal element transmittance (%) 92.43 98.61 95.84 Transmittance improvement (%) 4.31 7.07 2.28

[0052] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

[0053] ​Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes every feature or implementation described herein. The specification can include implicit combinations of explicitly mentioned features and / or implicit combinations of implicitly mentioned features. Such combinations are also expressly included within the scope of the specification and an embodiment.

Claims

1. A preparation method of a moisture-proof protective film for a nonlinear optical CLBO crystal anti-reflection, characterized in that, The method comprises the following steps: The hafnium n-propoxide sol is prepared by using organic alkoxide hafnium n-propoxide as a precursor; tetraethyl orthosilicate sol is prepared by using tetraethyl orthosilicate; the prepared sols are uniformly coated on the surface of the CLBO crystal to be protected by using a pulling method according to the ratio of 3-7wt% of the hafnium n-propoxide sol to the tetraethyl orthosilicate sol, and then the CLBO crystal with the sol-coated surface is heat-treated at 150-200℃ for 4-10 hours to form a dense HfO2 / SiO2 protective film layer.

2. The preparation method of the anti-moisture protective film for the nonlinear optical CLBO crystal according to claim 1, characterized in that, The preparation method of the hafnium n-propoxide sol specifically comprises the following steps: Acetylacetone with a purity of 99.9% or above is dissolved in anhydrous ethanol to prepare solution A with a mass concentration of 5-20wt%; hafnium n-propoxide with a purity of 99.9% or above is dissolved in anhydrous ethanol to prepare solution B with a mass concentration of 5-20wt%; Solution A is added drop by drop to solution B under the condition of vigorous stirring, and then hydrochloric acid with a mass concentration of 0.1-0.2wt% is added to adjust PH to 3-5; under the condition of 40-60℃, the mixture is stirred for 1-5 hours to obtain hafnium n-propoxide sol with a mass concentration of 3-8wt%.

3. The preparation method of the anti-moisture protective film for the nonlinear optical CLBO crystal according to claim 1, characterized in that, The preparation method of the tetraethyl orthosilicate sol specifically comprises the following steps: Tetraethyl orthosilicate with a purity of 99.9% or above is dissolved in anhydrous ethanol to prepare solution C with a mass concentration of 3-20wt%, and then hydrochloric acid with a mass concentration of 0.1-0.2wt% is added to adjust PH to 2-5; under the condition of 50-80℃, the mixture is stirred for 8-24 hours to obtain tetraethyl orthosilicate sol with a mass concentration of 2-9wt%.

4. The moisture-proof protective film of the nonlinear optical CLBO crystal prepared by the method of any one of claims 1-3, characterized in that, The HfO2 / SiO2 deep ultraviolet antifouling and moisture-proof protective film.

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