Dispersion compensated ring lasers for terahertz frequency comb and ultrafast terahertz detection

Abstract

We report frequency combs formation in THz QCL ring cavities with spectral bandwidth of similar to 400 GHz. In addition to the frequency comb operation sech(2)-shaped spectra are observed in RF-injected ring lasers and dispersion compensated double ring cavities, hinting at the existence of soliton regimes in the QCL. The device is also used below threshold to detect commercial THz frequency combs. High harmonics of the comb beatnote could be measured optically up to 67 GHz (670th harmonic).