Fast rate dual-comb spectrometer in the water-transparent 7.5-11.5 µm region.

We introduce a dual-comb spectrometer based on erbium fiber oscillators at 250 MHz that operates in the 7.5-11.5 µm spectral range over optical bandwidths up to 9 THz with a multi-kHz acquisition rate. Over an observation bandwidth of 0.8 THz, the signal-to-noise ratio per spectral point reaches 168 Hz