High speed THz spectroscopy using fast scanning Fabry-Perot

A fast-scanning tunable Fabry-Perot filter has been developed for signature identification in reflective THz sensor systems. The reflectors are metal mesh filters having reflectivity between 0.90 and 0.95, depending on the specific frequency. A demonstration of the filter has been carried out at 530 GHz with a resolution of ~10 GHz (Q ~ 50), a scan range of ~50 GHz, and a scan time of 0.5 seconds. The higher-order harmonic longitudinal modes are blocked by a lower-Q metamaterial bandpass filter located outside the Fabry Perot and having no harmonic passbands. This will enable high-rate THz spectroscopy without frequency ambiguity.