Characterization of QCL-Comb emission by Fourier Transform Analysis

Quantum cascade lasers (QCLs) frequency comb (FC) synthesizers represents the new frontier of miniaturized metrological grade sources, ideal for quantum sensing, metrology, communications and simulations. At terahertz (THz) frequencies, electrically pumped QCLs have shown quantum-limited intrinsic linewidths and can be absolutely referenced to the primary frequency standard. Fourier-transform analysis of comb emission (FACE) enables to asses the level of coherence of any QCL-FC on its entire frequency emission range simultaneously with the possibility to reconstruct its intensity emission profile and instantaneous frequency. Here, we present the novelties in FACE characterization method, proving the metrological nature of a promising new generation of THz QCL-FC.