Coherently-Averaged Dual-Comb Spectrometer at 7.7 µm with Master and Follower Quantum Cascade Lasers

Mid-infrared (MIR) quantum cascade laser (QCL) frequency combs are an appealing technology for dual-comb spectroscopy as they cover strong absorption bands of many relevant molecules in the MIR region and enable measurements with sub-microsecond time-resolution permitting novel insights into dynamical processes [1] . The comb properties can be directly controlled through the QCL driving current, the chip temperature or by electrical injection of the repetition frequency [2] . Nevertheless, full mutual stabilization of a QCL dual-comb spectrometer (DCS) has not yet been reported. In this work, we demonstrate a DCS with full mutual stabilization in a master-follower (MF) scheme (also known as master-slave) and the coherent averaging of its signal.