Quasi-Resonant Enhancement of the Extinction Ratio in the Amorphous Silicon Nanowire Grid Polarizer

Abstract

Spectral characteristics of thin-film nanowire grid polarizers based on amorphous silicon are numerically investigated. The extinction ratio, transmission coefficients, and reflection coefficients are calculated using the MC Grating code based on the rigorous coupled-wave analysis. It is found out that at particular structure parameters of the nanowire grid polarizer the extinction ratio increases to 10⁶ at the optical radiation wavelength of about 380 nm, which is characterized as a quasi-resonance effect. A dissipative-interference qualitative interpretation of this effect within the waveguide model is proposed. This interpretation is confirmed by the calculated field distribution patterns in the vicinity of the quasiresonance.