High-efficiency nine-port beam splitting output enabled by a dielectric lamellar sandwiched fused-silica grating

Abstract High-efficiency multi-beams output from diffraction optical element (DOE) with equal energy in parallel is of intense interest because high-performance multiple output beams can improve transmission rate of some key optical signals. Herein, we design a novel sandwiched fused-silica diffraction grating, which can operate at the high-efficiency nine-port beam splitting output with good uniformity. By performing rigorous coupled-wave analysis (RCWA) method, grating parameters and fabrication errors are optimized and discussed for TE and TM-polarized modes. A theoretical simplified modal method (SMM) can insight into an explicit light-matter coupling mechanism in grating area. In addition, for better evaluating real performances of the grating, incident spectral bandwidth of the grating can be fully investigated based on RCWA approach and finite-element method (FEM). Thus, this work can open up a possible way for optimizing more high-performance polarization-independent or polarization-dependent higher-order-port diffraction gratings.