用于谐波分离的三角形槽亚波长光栅误差分析

Tolerance analysis of sub-wavelength grating with triangle carving for separating harmonic waves

干净有效地实现3种谐波的分离,避免剩余无用的基频光和二倍频光对物理实验的影响,是目前高功率固体激光驱动器一直面临的难点,采用亚波长光栅进行谐波分离是一种全新的方法。基于能够实现高功率固体激光驱动器中3种谐波分离的三角形槽亚波长光栅设计参数,利用基于矢量衍射理论开发的商用软件Gsolver,分析光栅周期、入射角、占空比、刻槽深度等光栅参数对亚波长光栅谐波分离的能力,即三倍频光衍射效率的影响。结合谐波分离的基本要求,给出了亚波长光栅的加工误差要求:满足谐波分离的亚波长光栅的各项参数的误差范围均在亚微米量级,其中加工精度要求最高的是刻槽深度。为亚波长光栅应用于高功率固体激光驱动器谐波分离提供了理论支持。

Achieving a clean and effective separation of harmonic waves,and to avoid the unwanted 1ω and 2ω on the impact of physical experiments,is one of the key problems in the high-power solid-state laser diver.Using the sub-wavelength grating for separating harmonic waves is a new way.Based on designed sub-wavelength grating with triangle carving for separating harmonic waves in high-power solid laser facility,the impact were analyzed on 3ω diffraction efficiency varied with the grating period,incident angle,duty ratio,and carving depth.Software Gsolver was used.The machining tolerances were provided,according to the basic demand of the harmonic waves separation.The parameters of sub-wavelength grating are all in the sub-micron range,and the highest precision machining tolerance is the carving depth.The work provides theoretical basis for the application of sub-wavelength grating on the area of harmonic waves separation in high-power solid laser facility.