Low-loss compact high-Q 3D THz grating resonator based on a hybrid silicon metallic slit waveguide

We present a high-Q 3D waveguide transmission filter for the THz-domain, based on an inhomogeneous Bragg grating, incorporated into the walls of a metallic slit waveguide. The reasons for the occurring loss mechanisms in the compact component are presented and the losses are minimized by selective mode adaptation and by tapering the transitions to the corrugated regions. The performance of the device and the influence of parameter variations are analyzed by detailed numerical simulations. These 3D simulations clearly show the drastic drawback of 2D calculations in designing narrowband 3D metal-dielectric waveguide filters and could even lead to a better performance than known designs in 2D technology.