Continuously-tunable doubly resonant optical parametric oscillator

We report on an all-solid-state source of broadly tunable single-frequency radiation from a continuous-wave (CW), doubly resonant optical parametric oscillator (OPO) based on non-critically phase-matched magnesium oxide-doped lithium niobate (MgO:LiNbO₃). The oscillator is pumped by the second harmonic of a single-frequency Nd:YAG miniature ring laser at 532 nm and provides combined signal and idler output power of nearly 400 mW CW. Covering a tuning range between 1007 and 1128 nm, stable operation on a single-axial-mode pair is obtained for several hours without mode hops using an FM sideband-locking technique. The output frequencies of the OPO can be continuously tuned over a range of 8 GHz via precise control of the pump laser frequency.