基于严格耦合波理论的亚波长光栅优化设计

亚波长衍射光栅的衍射效率不但与入射光的特性有关,而且与光栅结构和折射率等参数有关。采用严格耦合波理论对亚波长光栅的衍射效率公式进行了推导,对不同光栅结构参数(周期、槽深,占空比)和光栅脊、槽的折射率的亚波长衍射光栅的衍射效率进行了数值计算并用MatLab软件进行仿真模拟,光栅槽深与周期的比值为0.425,占空比为0.507,并且光栅脊、光栅槽的折射率为2.37时,得到具有最佳滤波和衍射效果的亚波长光栅的优化结构。

The optimal design for sub-wavelength grating based on the rigorous coupled wave theory

The diffraction efficiency of the sub-wavelength diffraction grating is not only related with the characteristics of the incident light, but also with the grating structure and the refractive index and other parameters. In this paper, we deduced from the formula of the sub-wavelength grating with the rigorous coupled wave theory. We conducted the numerical calculating of diffraction efficiency for sub-wavelength gratings with different structure parameters（period, groove depth, duty cycle）and different refractivities, then we simulated with MatLab. By this method we obtained the sub-wavelength grating structure with best filtering and best diffraction result at d/A=0. 425, duty cycle 0. 507, nrd/ngr=2. 37.