Modal analysis of the quasi-resonant extinction ratio enhancement in the amorphous silicon wire grid polarizer

Abstract

The previously discovered effect of quasi-resonant enhancement of the extinction ratio in an amorphous silicon wire polarizer is investigated using the Bloch wave approach and the modal method. Effective indices of grating modes, modal fields and transmission coefficients were numerically evaluated and our prior hypothesis of destructive interference of lower order grating modes as a mechanism for the enhancement of the extinction ratio was confirmed. Using the numerical optimization, we showed that the quasi-resonance wavelength can be tuned by changing the parameters of the grating structure.