500 GHz sensor system in SiGe for gas spectroscopy

A 500 GHz sensor system for gas spectroscopy is presented, which includes a SiGe transmitter (TX) array and a SiGe receiver (RX). The integrated local oscillators of the TX-array and RX chips are controlled by two external phase-locked loops (PLL). The reference frequency of the TX-array PLL is modulated for 2f absorption spectroscopy (second harmonic detection). The performance of the sensor system is demonstrated by detecting the 2f absorption spectra of methanol and acetonitrile.