Room-Temperature Continuous-Wave Frequency-Referenced Spectrometer up to 7.5 THz

An innovative spectrometer demonstrates the possibility of realizing room-temperature generation and detection of continuous-wave THz radiation spanning three octaves in frequency, and enabling molecular spectroscopy with state-of-the-art accuracy. The setup is based on a simple, reliable approach that combines robust telecom-laser components, nonlinear difference-frequency generation, and frequency-comb-assisted referencing to a primary frequency standard. The combination of ultrabroad-band coverage and microwatt power levels in a single source could pave the way to metrological-grade sources spanning most of the THz range, for countless demanding applications.