QCL based terahertz frequency metrology

Quantum cascade lasers combine unique features in the framework of THz sources, namely compactness and mW output power. In addition, owing to an intrinsically low phase-noise level, they are suitable for frequency and phase stabilization, which makes them attractive sources for frequency metrology applications, and able to overcome the power limits of current microwave-traceable THz emitters. In this contribution, we address metrological grade THz quantum cascade lasers from their intrinsic spectral feature to the use of optical frequency combs as frequency reference.