Fourier transform spectroscopy around 3 μm with a broad difference frequency comb.

We characterize a new mid-infrared frequency comb generator based on difference frequency generation around 3.1 μm. High power per comb mode (>10−7 W/mode) is obtained over a broad spectral span (>750 nm, >790 cm−1). The source is used for direct absorption spectroscopy with a Michelson-based Fourier transform interferometer