大尺寸1064nm波段HfO_2/SiO_2高损伤阈值窄带滤光片的研制

Fabrication of Large Size 1064 nm HfO_2/SiO_2 Narrow-Band Filters with High Laser Damage Threshold

对大型固体激光装置中的关键器件—大尺寸1064 nm波段Hf O2/Si O2窄带滤光片进行了研究,分析了监控波长对信噪比和光源稳定性的影响。通过优化监控参数,设备监控精度可达到镀制窄带滤光片的需求。制备过程中的薄膜光谱分析表明:随着蒸镀过程的进行,氧化铪(Hf O2)的实际厚度会逐渐小于设计值,而二氧化硅(Si O2)的实际厚度则会逐渐大于设计值;这种变化趋势导致的厚度误差会严重影响带通的波形;另外掩模板造成的厚度误差也是影响带通波纹的重要因素之一。通过分析研究和优化以上因素,制备了半峰全宽为5 nm、通光口径达200 mm×200 mm、在1064 nm处损伤阈值高于19.5 J/cm^2(3 ns)的窄带滤光元件。

Narrowband filters with central wavelength 1064 nm are key optical elements used in the large scale solid state laser facility. In order to fabricate a filter with large size and high precision, the influence of monitoring wavelength on signal noise ratio and stability is investigated. Moreover, the monitoring strategy is optimized to satisfy the precision need for fabricating a narrowband filter. Film spectra analysis in fabrication process indicates that the actual thickness of Hf O2 will smaller than design value gradually, and the actual thickness of Si O2 will greater than design value gradually, with the proceed of coating. The thickness error as a result of the different variation tendency for Hf O2 and Si O2 in the evaporation process, and the mask plate induced error are key points of affecting the bandpass property. One 200 mm × 200 mm size narrowband filter with 5 nm full width at half maximum（FWHM） and over 19.5 J/cm2（3 ns） laser damage threshold at 1064 nm is successfully fabricated.