Pump-tunable continuous-wave singly resonant optical parametric oscillator from 2.5 to 4.4 µm

We report a continuous-wave singly resonant optical parametric oscillator pumped by a widely tunable titanium-doped sapphire ring laser. It produces up to 0.8 W of mid-infrared power. The wavelength can be tuned in a few seconds from 2.5 to 3.5 µm or from 3.4 to 4.4 µm and scanned up to 40 GHz without mode-hops by only changing the pump beam wavelength. Spectroscopic capability is demonstrated by measuring parts of the photoacoustic absorption spectrum of NH3 near 3196 cm⁻¹.