High average power 2 μm generation using an intracavity PPMgLN optical parametric oscillator

An intracavity quasi-phase-matched optical parametric oscillator (OPO) has been developed for the purpose of generating radiation with high average power and high repetition rate in the 2 μm regime. The device is a degenerate OPO based on a 3 mm thick MgO-doped periodically poled LiNbO(3) (PPMgLN) crystal, which is pumped in turn within the cavity by a diode side-pumped, Q-switched 1 μm Nd:YAG laser operating at 10 kHz. Up to 20 W broadband 2 μm radiation can be generated with a compact configuration under the crystal temperature of 115 °C. The beam profile is close to circularly symmetric with M(2) ~ 10.