Gas Spectroscopy at 222 – 270 GHz Based on SiGe BiCMOS using a Multi-Pass Ring Cell

We present broadband gas spectroscopy based on SiGe BiCMOS technology. A bandwidth of about 222-270 GHz is achieved by a combination of two frequency bands on single transmitter and receiver chips. The antennas of transmitter and receiver for both bands are closely placed on a single chip such that coupling into the same optical system can be realized. We coupled the beams into a compact custom-made multi-pass ring cell with an optical path length of 1.9 m. We demonstrate sensitive gas spectroscopy capabilities by a full bandwidth spectrum of methanol.