Resonant Terahertz Field-effect Transistors for Spectroscopic Sensing Applications

We present a system concept which can enable spectroscopic sensing applications over a broad frequency range and with high speeds. To address spectral sensitivity at distinct frequency lines, we use antenna-coupled terahertz field-effect transistors (TeraFETs) with resonant patch antennas in combination with a broadband pulsed terahertz source with fast pulse repetition rates of 100 MHz. To enhance the spectral sensitivity at the selected frequencies, we combine the TeraFETs with resonant filters based on frequency selective surface (FSS) structures in thin metal layers. We demonstrate possible applications of spectroscopic sensing such as material identification via spectral fingerprints or water vapor monitoring.