Actively mode-locked optical parametric oscillator.

We report on what we believe to be the first demonstration of active mode locking of an optical parametric oscillator. An acousto-optic modulator is inserted into a nearly degenerate (approximately 1064 nm) and doubly resonant optical parametric oscillator based on periodically poled LiNbO3 and pumped with the second harmonic of a quasi-continuous-wave single-frequency Nd:YAG laser. When the modulation frequency is matched to the free spectral range of the cavity (120 MHz), a pulsed regime is observed, with pulse durations as short as 700 ps.

Single-frequency quasi-continuous red radiation generated by a green-pumped singly resonant optical parametric oscillator.

We demonstrate the operation of a quasi-continuous-wave optical parametric oscillator (OPO) in the red part of the visible spectrum by direct pumping from a frequency-doubled quasi-continuous-wave Nd:YAG laser. The OPO is singly resonant and based on a MgO-doped periodically poled stoichiometric lithium tantalate crystal. A single-frequency 1.2 W output power is obtained when an etalon is inserted inside the cavity.