COMB-REFERENCED ULTRA-HIGH SENSITIVITY SPECTROSCOPIC MOLECULAR DETECTION BY COMPACT NON-LINEAR SOURCES

We present a new generation of compact and rugged mid-infrared (MIR) difference-frequency coherent radi-ation sources referenced to fiber-based optical frequency comb synthesizers (OFCSs). By coupling the MIR radia-tion to high-finesse optical cavities, high-resolution and high-sensitivity spectroscopy is demonstrated for CH4 and CO2 around 3.3 and 4.5 µm respectively. Finally, the most effective detection schemes for space-craft trace-gas monitoring applications are singled out. Key words: difference-frequency generation; optical fre-quency comb; high-sensitivity gas sensing. 1