BETA-BARIUM BORATE AND LITHIUM TRIBORATE PICOSECOND PARAMETRIC OSCILLATORS PUMPED BY A FREQUENCY-TRIPLED PASSIVE NEGATIVE-FEEDBACK MODE-LOCKED ND-YAG LASER

We report on an investigation of a singly resonant picosecond optical parametric oscillator in a noncollinear configuration for which we alt ernatively used beta-barium borate and lithium triborate in a type-I p hase-matching configuration tunable from 407 to 2780 nm and from 452 a nd 1650 nm, respectively. The parametric oscillator was synchronously pumped by the third harmonic of a passive negative-feedback actively-p assively mode-locked Nd:YAG laser-amplifier system, and long and flat trains of short bandwidth-limited 9-ps pulses were produced. We obtain ed conversion efficiency into the idler wave (at 900 nm) of as high as 10% and overall efficiency as high as 26%. We present a numerical mod el of the operation that agrees very well with the experimental result s. The simplicity and ruggedness are the main strengths of this source when high-power conversion capability and wide tunability are the mai n requirements.