Quantum cascade laser-based dual-comb spectroscopy in the mid-infrared

We demonstrate sub-millisecond response time dual-comb spectroscopy using quantum cascade lasers by measurements of Bromomethane and Freon 134a around 7.7 μm. The system achieves a noise-equivalent absorption of <;1 × 10
^-3
Hz
^-1/2
and an optical bandwidth of ~25 cm
^-1
.