Broadband polarizing beam splitter with metal-wire nanograting in near infrared region

Abstract

A broadband polarizing beam splitter (PBS) with metal-wire nanograting in near infrared region is designed and analyzed. The grating profiles are optimized by use of rigorous coupled-wave analysis (RCWA) and the simulated annealing (SA) algorithm. Based on the optimized structure, high polarization efficiency, high extinction ratio and large angular tolerance with a broad wavelength range (1–3μm) are obtained. Both of the transmission efficiencies of TM-polarization and reflection efficiencies of TE-polarization are over 95%. The extinction ratio of transmittance and reflectance are over 25dB and 16dB in the 1–3μm wavelength range, respectively. At the same time, as a comparison we also design a PBS with double-groove metal-wire nanograting, the grating has two grooves per period, which is different from conventional gratings. The PBS also has large angular tolerance, which is −40° to 40°. The designed grating can be used in optical communication and infrared imaging polarimetry.