Low-loss frequency selective surfaces on silicon substrates for sub-millimeter wave applications

A new class of frequency selective surfaces (FSSs), to be used as quasi-optical filters for harmonic suppression in sub-mm wave frequency multipliers, is proposed and experimentally verified. The FSSs consist of two-dimensional aperture arrays, and are made from microstructured aluminium on electrically thick, high-resistivity silicon substrates. This leads to a very good mechanical stability, low insertion loss, and permits the structure to be manufactured using standard processes available from the semiconductor industry. The paper presents the design, fabrication, and testing of two sets of prototypes, the former with a pass-band at 300 GHz and a stop-band at 450 GHz and the latter with a pass-band at 600 GHz and a stop-band at 750 GHz.