溶胶凝胶ZrO_(2)/SiO_(2)宽带减反膜的制备与性能

Preparation and Properties of Sol-Gel ZrO_(2)/SiO_(2) Broadband Antireflective Film

采用溶胶凝胶法制备得到以正丙醇锆和正硅酸乙酯为前驱体的ZrO_(2)和SiO_(2)溶胶,通过TFCalc光学薄膜软件模拟了ZrO_(2)/SiO_(2)三层“宽M型”基频二倍频减反膜,并使用提拉法制备得到了该均匀膜层。三层减反膜在527 nm和1053 nm处的透过率约为99.5%,且透过率大于99%的波长范围均超过150 nm。经热处理后的膜层表面均方根粗糙度为1.34 nm,表面平整性良好;并运用1-on-1激光损伤阈值测试方法测得该减反膜的零几率激光损伤阈值达到36.8 J·cm^(-2)(1064 nm,10.7 ns)。

Objective Preparing chemical films using the solgel method is very important in inertial confinement fusion laser devices.The antireflective(AR)films could be coated on glass elements such as target mirror,antisplash plate,beam sampling grating,and potassium dihydrogen phosphate/deuterated potassium dihydrogen phosphate(KDP/DKDP)crystal elements to achieve optical performance enhancement at specific wavelengths.The optical elements coated with AR films have a high laserinduced damage threshold(LIDT)due to the porous properties of the films.KDP/DKDP nonlinear optical elements for frequency doubling conversion need to simultaneously and efficiently transmit light with mixed wavelengths,which can be realized by coating different chemical AR films on them.Then,the system energy loss caused by the terminal components will be reduced during the operation of highpower laser devices.Methods ZrO_(2) and SiO_(2) sols were prepared by the solgel method with zirconium npropoxide and tetraethoxysilane as precursors.The threelayer"wideMtype"first harmonic and second harmonic AR film of ZrO_(2)/SiO_(2) was simulated by TFCalc optical film software and prepared by the dip coating method,and SiO_(2) doublelayer broadband AR film was prepared by the same method for performance comparison.The optical property,refractive index,micromorphology,and other characteristics of the threelayer"wideMtype"ZrO_(2)/SiO_(2) film were measured and analyzed by a UVVis spectrometer,a spectroscopic ellipsometer,a scanning electron microscope,and other equipment.Results and Discussions On the basis of an optical principle,the nonquarterwavelength threelayer"wideMtype"film system with a refractive index combination of 1.65/1.42/1.2 on K9 substrate(refractive index is 1.52)was simulated by TFCalc(Fig.1).This study selected ZrO_(2) and SiO_(2) as the materials of the threelayer solgel film,considering the existing solgel technology of the research group and simulation results.The transmittance of the uniform threelayer AR film at 527 nm and 1053 nm was about 99.5%,and the wavelength range where the transmittance was greater than 99%exceeded 150 nm(Fig.3).This optical performance was significantly better than that of the twolayer AR film,which improved the fault tolerance of the film thickness during the film preparation(Fig.4).The surface of threelayer AR film was smooth after heat treatment whose rootmeansquare roughness was 1.34 nm(Fig.5),which could reduce the influence of scattering formed on the film surface on the luminous flux,energy loss,and beam quality in the laser device system.The zeroprobability LIDT of the threelayer AR film reached 36.8 J·cm^(−2)(1064 nm,10.7 ns)measured by the 1-on1 LIDT test method,and the result was similar to that of the doublelayer film(Fig.7).The porous property of randomly stacked solgel film during film formation made the LIDT of the threelayer film not decrease,though a layer of ZrO_(2) film was added(Fig.6).Conclusions ZrO_(2) sol was prepared with zirconium npropoxide as the precursor by the Stöber method.Based on the existing mature SiO_(2) sol technology of the research group,the threelayer ZrO_(2)/SiO_(2) film was prepared on a K9 substrate through simulation and experiment,which could give consideration to the high antireflection at both 1053 nm and 527 nm.The threelayer ZrO_(2)/SiO_(2) film had good optical properties,surface roughness,and LIDT,which could broaden the range of selecting chemical film materials suitable for highpower devices.In future work,the stability of the threelayer ZrO_(2)/SiO_(2) film under different environmental conditions needs to be systematically studied for a better understanding of it.