We report a femtosecond optical parametric oscillator (OPO) based on the new semiconductor gain material orientation- patterned gallium phosphide (OP-GaP), which enables the production of high-repetition-rate femtosecond pulses span- ning 5–12 μm with average powers in the few to tens of milli- watts range. This is the first example of a broadband OPO operating across the molecular fingerprint region, and we demonstrate its potential by conducting broadband Fourier- transform spectroscopy using water vapor and a polystyrene reference standard.
Maidment, L., Schunemann, P. G., & Reid, D. T. (2016). Molecular fingerprint-region spectroscopy from 5 to 12 μm using an orientation-patterned gallium phosphide optical parametric oscillator. Optics Letters, 41(18), 4261-4264. https://doi.org/10.1364/OL.41.004261