Design of multi-layer dielectric grating for femtosecond laser

以薄膜光学的干涉理论和衍射光学的傅里叶模式理论为基础，给出了0．8μm飞秒激光器用多层介质膜脉宽压缩光栅的理论设计；设计采用H3L（HL）^9H0．5L2．4H的多层介质膜为基底，当刻蚀后表面浮雕结构的占宽比为0．35，线密度为1480线／mm，槽深为0．2μm，顶层HfO2的剩余厚度为0．15μm时，对于Littrow角度（36．7°）和TE波模式入射的衍射光栅其-1级衍射效率达到95％以上．Based on optical interference theory and Fourier modal theory, a new multi-layer dielectric gratings is designed for use in femtosecond laser system at wavelength 0.8 mu m. A multi-layer dielectric with stack of H3L(HL)<^>9H0.5L2.4H is used as a substrate to be etched with corrugated structure. Numerical computation indicates that the diffraction efficiency of - I order can be more than 95% when the parameters of multi-layer dielectric grating are the following: laser is incident on-the grating at 36.7 degrees in TE mode, the duty cycle is 0.35 and the line density is 1480/mm, the groove depth is 0.2 mu m and the top residual HfO2 is 0.15 mu m