THz-comb-assisted molecular spectroscopy

Thanks to the recent progresses in photonics and nanotechnology, Terahertz (THz) radiation is finding increasing use in a wide range of applications. Since their first demonstration, THz Quantum Cascade Lasers (QCLs) have been the most important sources for a large range of applications and also for fundamental research. An important characteristic of THz QCLs is the very low intrinsic linewidth of their emission [1], at a level of tens of Hz, and this further qualifies them as ideal metrological sources. Moreover thanks to recent improvements in THz technology, robust and versatile metrological frequency references are available [2-4], enabling absolute measurements of THz frequencies.