Two-dimensional polarization-insensitive grating with broadband and large incident angle tolerance

In this work, we propose a two-dimensional grating under Littrow configuration, featuring high diffraction efficiency (DE), polarization insensitivity, a broad wavelength band, and large incident angle tolerance. The grating has a simple structure consisting of dielectric nano-cylinder arrays and a silver (Ag) reflective layer, with its geometric parameters optimized using rigorous coupled-wave analysis method. Over the incident wavelength range of 1016 nm to 1087 nm, the diffraction efficiencies of the (−1, 0) order for both transverse electric and transverse magnetic polarizations exceed 90%. Specifically, at a wavelength of 1064 nm, for the incident angle range from 17.32° to 37.52°, the DE of the (−1, 0) order exceeds 90%. Moreover, an analysis of the grating fabrication tolerances confirms its manufacturing feasibility and application potential in grating interferometers and spectral beam combining systems.