Fast mid-infrared dual comb spectroscopy from a single cw-OPO

Mid-infrared tunable laser absorption spectroscopy is used for experiments in chemical kinetics, combustion diagnostics, and hypersonic flow. In these applications spectra evolve rapidly, demanding a fast acquisition rate. Wider spectral coverage per acquisition reveals more absorption features of the target species or multiple species. However, typically spectral coverage decreases with faster acquisition. We improve the speed or spectral bandwidth by 1-3 orders of magnitude compared to the state of the art. A near-infrared dual comb is used to pump a singly-resonant continuous-wave optical parametric oscillator (OPO). The resonant OPO signal is single frequency, so the OPO spectrally translates the pump spectrum to its non-resonant mid-infrared idler output. Using an electro-optic dual comb pump we achieve extremely fast acquisition (1 cm-1 at 50 MHz), and using a dual mode-locked fiber comb pump we demonstrate wide spectral coverage (> 10 cm-1 at 10 kHz), all with > 1 Watt optical power.