在千焦拍瓦高功率放大系统设计中,激光脉冲的时空和光谱整形技术一直受到人们的广泛关注。利用反应离子束刻蚀等微纳超精细加工而成的多层电介质结构反射镜可在高功率条件下实现啁啾脉冲的光谱整形。在光谱整形介质结构反射镜的设计与制造中,需要根据要求的反射率来合理提出反应离子束刻蚀误差容限指标。推导出反应离子束刻蚀误差容限的解析表达式。针对神光Ⅱ千焦拍瓦高功率放大系统设计中提出的多层介质光谱调制反射镜,分析了调制结构反射镜各层加工的容许误差,确定了反应离子束刻蚀误差容限指标。研究表明:刻蚀高折射率介质的加工误差容限为35 nm;刻蚀低折射率介质的加工误差容限为62 nm。此外,还从使用需要和加工难易的角度,对刻蚀方案进行了讨论。就加工难易程度而言,优选反应离子束刻蚀方案,且采用刻蚀并残留低折射率介质的方案更容易实现。

Lots of attentions have been paid to the spatial distribution,the temporal profile,as well as the spectrum reshaping in the design of kilo-joule peta-watt chirped pulse amplification (CPA) systems.The multilayer dielectric thin film reflector fabricated by top-down nano-fabrication processes can be used to realize spectral reshaping of high power chirped pulse.In the design and fabrication of the reflector,it is necessary to determine the tolerance of ion beam etching appropriately based on the design goal.Therefore,the analytical expression for the tolerance of ion beam etching of the multilayer dielectric thin film reflector for spectral reshaping of chirped pulse laser in large energy and high power Nd:glass CPA system has been derived.The error limitation of ion beam etching for layer the each of film has been analyzed,and the tolerance of ion beam etching for the multilayer dielectric thin film reflector have been proposed.Study shows that.etching high refractive index material layer,the etching tolerance Δmax is 35 nm,equivalent to λ/15 error tolerance,for low refractive index one,Δmax is 60 nm,a considerable margin in the erroe tolerance of λ/11.Furthermore,according to the application requirement and the fabrication capability,the etching methods have also been discussed.