Optical frequency comb generation in the mid ir

We have experimentally demonstrated the metrological and spectroscopic performances of a mid-IR comb generated by a nonlinear down-conversion process from a Ti:sapphire-based near-IR comb. A quantum cascade laser at 4330 nm was phase-locked to a single tooth of this mid-IR comb and its frequency-noise power spectral density was measured. The mid-IR comb itself was also used as a multi-frequency highly coherent source to perform ambient air direct comb spectroscopy with the Vernier technique, by demultiplexing it with a high-finesse Fabry-Perot cavity.