厳密結合波解析による色分離用回折格子の最適設計と評価

抄録

In this study, we focused on a small and light grating that is capable of converting efficiently white light into only the three primary colors red, green and blue. To evaluate its diffraction characteristics properly, we performed a rigorous electromagnetic analysis based on the rigorous coupled wave analysis (RCWA). We designed the grating such that diffraction efficiency higher than 70 % and a color gamut higher than 65 % were obtained. On the basis of our numerical results, we then fabricated a grating by laser drawing and determined its color separation efficiency. The grating was etched into quartz and had a six-level surface relief, a maximum groove depth of 5.75 m, and a period of 50μEm. Furthermore, we calculated the tolerances of fabrication errors in the depth and width directions that satisfy optimal design conditions for establishing guiding principles for the accurate fabrication of multilevel color separation gratings with deep grooves.