Under CopyrightNitzsche, LeonardLeonardNitzscheGoldschmidt, JensJensGoldschmidtKießling, JensJensKießlingWolf, SebastianSebastianWolfKühnemann, FrankFrankKühnemannWöllenstein, JürgenJürgenWöllenstein2022-03-1416.4.20212021https://publica.fraunhofer.de/handle/publica/41037610.1117/12.2578371A dual frequency comb spectrometer is realized by electro-optic modulation of a 1550 nm laser and subsequent conversion to the mid-infrared by difference-frequency generation (DFG). Using an optical parametric oscillator for the DFG the combs can be tuned from 3 mm to 4.7 mm with 440 comb modes covering 220 GHz (< 6 cm-1). Trace gas detection of nitrous oxide, carbon dioxide and methane is demonstrated with a 7.2-m-multi-pass cell while a sufficiently low noise-equivalent absorbance is reached in already 1 s. The bandwidth normalized noise-equivalent-absorption coefficient is consistently below 2.8 × 10-6 Hz-1/2 cm-1 while the precision of the determined concentrations is better 2 % Hz-1/2.enfrequency combspectrometertrace gas621conference paper