Reflection analysis of absorbing film with diffractive structures for incoherent light by rigorous coupled-wave analysis

Reflectivity is useful for evaluating the extinction coefficient; however, it is highly sensitive to the refractive index structure. In this study, we propose a novel, to the best of our knowledge, method for evaluating the influence of the structure on reflectivity using rigorous coupled-wave analysis (RCWA), and apply it to analyze the reflectivity of the dye rhodamine B. The reflection-absorption spectrum of the film was significantly affected by its surface and internal structure. We found that simulating the reflectivity of a film with an unknown internal structure using the coherency parameter is convenient. The RCWA facilitated simultaneous treatment of the coherent diffraction by the surface structure and incoherent reflection in the film. (C) 2021 Optical Society of America

Automated summary

Reflectivity is useful for evaluating the extinction coefficient but sensitive to refractive index structure. A novel method using RCWA to assess the influence of structure on reflectivity was proposed and applied to analyze the reflectivity of rhodamine B dye. The reflection-absorption spectrum of the film was significantly influenced by its surface and internal structure.