Coherent mid-infrared dual-comb spectroscopy enabled by optical injection locking of quantum cascade laser frequency combs

Mid-infrared frequency combs are emerging as powerful tool for broadband spectroscopy in the molecular fingerprint region. Dual-comb spectroscopy is particularly promising due to its high temporal and spectral resolution. In many practical applications, quantum cascade laser (QCL) frequency combs [1] are the source of choice, because they are electrically pumped, have a small footprint and offer an unrivalled brightness. Albeit being a relatively new technique, dual-comb spectroscopy based on QCLs [2] has already enabled high-speed spectroscopy with extremely high spectral resolution [3] .