Broadband terahertz heterodyne spectrometer exploiting synchrotron radiation at megahertz resolution

A new spectrometer allowing both high resolution and broadband coverage in the terahertz (THz) domain is proposed. This instrument exploits the heterodyne technique between broadband synchrotron radiation and a quantum-cascade-laser-based molecular THz laser that acts as the local oscillator. Proof of principle for exploitation for spectroscopy is provided by the recording of molecular absorptions of hydrogen sulfide (H2S) and methanol (CH3OH) around 1.073 THz. Ultimately, the spectrometer will enable to cover the 1–4 THz region in 5 GHz windows at Doppler resolution.