Terahertz Polarization-Maintaining Grating Based on Dielectric Subwavelength Waveguide

In polarization-sensitive terahertz (THz) communication systems, grating is one of the essential components that filters THz waves at desired frequencies. Based on dielectric rectangular subwavelength waveguide, we propose a THz grating structure to filter two orthogonally polarized states. From numerical simulations, the proposed filter has two passbands with over 20.9 dB extinction ratio and around 21.1 GHz full-width half-maximum. Moreover, by introducing a π-phase shift, the grating can operate as a polarization-maintaining narrow bandpass filter with over 12.3 dB extinction ratio and less than 1.7 GHz full-width half-maximum.