Terahertz heterodyne spectroscopy of radio-frequency-driven frequency combs without moving parts based on telecommunication technology

We present heterodyne spectroscopy measurements up to 0.76 THz of a frequency comb generated by a terahertz emitter driven by a near-infrared source. This source consists of a narrowband (< 100 Hz), continuous wave, 1550.12-nm, telecommunication-wavelength laser and a high-precision radiofrequency signal generator, which drives a Mach-Zehnder interferometer to produce a wideband, near-infrared frequency comb with a mode spacing and repetition rate of 10 GHz. We synchronized this source to external reference sources and evaluated its potential as a replacement for conventional, mode-locked, cavity-based laser sources in terahertz frequency combs.