Mid-infrared femtosecond optical frequency combs were produced by difference frequency generation of the spectral components of a near-infrared comb in a 3-mm-long MgO:PPLN crystal. We observe strong pump depletion and 9.3 dB parametric gain in the 1.5 μm signal, which yields powers above 500 mW (3 μW/mode) in the idler with spectra covering 2.8 μm to 3.5 μm. Potential for broadband, high-resolution molecular spectroscopy is demonstrated by absorption spectra and interferograms obtained by heterodyning two combs.
© 2015 Optical Society of America
Cruz FC, Maser DL, Johnson T, Ycas G, Klose A, Giorgetta FR, Coddington I, Diddams SA. 2015. Mid-infrared optical frequency combs based on difference frequency generation for molecular spectroscopy. Optics Express: 23(20): 26814-26824.