High-efficiency polarization-selective two-dimensional diffraction gratings based on silver cuboid arrays

Abstract

A two-dimensional (2D) diffraction grating based on silver cuboid arrays is demonstrated. With the structural optimization by three-dimensional (3D) finite-difference time-domain method, the proposed grating exhibits favorable polarization selectivity. At wavelength 1550 nm, high diffraction efficiency and polarization correlation can be realized in the case of two-port output ((0, ±1) or (±1, 0)) under TE polarization, as well as five-port output ((0, 0), (0, ±1) and (±1, 0)) under TM polarization. Under the two-port output state, the diffraction efficiency is nearly 48% with the extinction ratio of 16.44 dB and insertion loss of 0.20 dB. Under the five-port output status, the efficiency is larger than 19% for each diffraction order, meanwhile, the total efficiency and uniformity are 97% and 0.58 %, respectively. The proposed grating with positive implications has good potentials in polarization multiplexing and polarization-correlated grating interferometry.