薄膜光学锥形光栅的制备与光学特性分析

为了在光学薄膜中引入连续轮廓的微结构，综合利用薄膜的干涉效应与微结构的折反射、衍射效应，提出一种薄膜光学微结构的制备工艺。基于时域有限差分方法设计了具有可见光波段减反射特性的薄膜光学锥形光栅；采用单点金刚石车削技术，结合纳米压印与电感耦合等离子体刻蚀技术，在SiN_x薄膜中制备出高1.6 μm，周期4.1 μm的锥形光栅；在可见光波段，SiN_x薄膜光学锥形光栅的平均反射率为5.7%，反射率的实验检测结果与仿真计算结果达到很高的一致性；当入射光角度在30°以内，薄膜光学锥形光栅的减反特性表现出对光波入射角度的不敏感性。该制备工艺突破了单点金刚石车削技术的材料局限，将连续轮廓的微结构的直接形成工艺拓展至介质薄膜当中，实现了宽光谱、宽入射角度的减反射。

Fabrication and optical properties analyses of thin film optical tapered grating

In order to introduce a continuous contoured microstructure into the optical thin film, the refraction, diffraction of the microstructures and the interference of the thin film were comprehensively utilized, and the preparation process of the thin film optical microstructure was proposed. The thin film optical tapered grating with anti-reflection characteristics in visible light was designed based on the finite difference time domain method. A tapered grating having a height of 1.6 μm and a period of 4.1 μm was prepared in the SiNx film by single point diamond turning technology, combined with nanoimprint lithography and inductively coupled plasma etching, In the visible band, the SiNx thin film optical tapered grating had an average reflectance of 5.7%, and the experimental results of the reflectance were highly consistent with the simulation results; when the incident angle was within 30°, the anti-reflection characteristic of the thin-film optical tapered grating exhibited an insensitivity to the incident angle of the light waves. It is indicated that the preparation process breaks through the material limitations of the single point diamond turning technology, it can extend the direct formation process of the continuous contour microstructure into the dielectric thin film, and can achieve the anti-reflection of wide spectrum and wide angle.