Influence of roughness on scattering characteristics of periodic micro-nano optical structures

During the preparation of optical films, each interface of the film system will deviate from the ideal shape of the smooth surface, and micro-roughness optical surface formed by random fluctuation of film thickness. With the rapid development of thin-film/semiconductor chip micro-nano periodic structures, periodic units and defect sizes are gradually approaching the nano-level, the influence of the roughness of the optical surface on the overall performance of the system cannot be ignored. Based on the three dimensional FDTD/MRTD algorithm, the system studies the light field distribution characteristics of the surface of complex optical structures at the micro-nano scale. Numerically analyze the optical field characteristics of the film surface with a multilayer periodic structure, and obtain the key parameters that affect the optical field of the film surface by analyzing the changes of the structure parameters. In view of the special structure of the multilayer periodic structure film, the concept of roughness is introduced to analyze the surface field changes on the surface of the multilayer film when the roughness exists, discuss the influence of the change of roughness parameters on the light field distribution, and give the influence law a detailed physical explanation.