500 GHz mode-hop-free idler tuning range with a frequency-stabilized singly resonant optical parametric oscillator.

A 1064 nm pumped continuous-wave, mid-IR (3-4 µm), signal-wave resonant optical parametric oscillator is frequency stabilized at the kilohertz jitter level to the transmission peak of an external high-finesse Fabry-Perot cavity. Owing to the high stability of the resonator length against acoustical perturbation, fine pump tuning of the idler wave around 3.3 µm results in an unprecedented mode-hop-free continuous scan over 500 GHz (17 cm⁻¹).