Diffraction grating polarization beam splitter using nano optical slits

Abstract

In this work a polarization sensitive diffraction grating is proposed that has an effective density of lines being different according to the polarization of the input. This results in diffracting different polarizations at separate angles. The structure of the proposed diffraction grating consists of an arrangement of nanoscale waveguides in a metal slab. The structure is simulated using the finite difference time domain technique. The diffraction pattern from the structure is calculated using an integral expression for the free space propagation after the diffraction grating. A first order diffraction at an angle of 10.3° with an extinction ratio of 22.8 dB was obtained for one polarization and an angle of 15.7° with an extinction ratio of 23.4 dB was obtained for the second polarization.