Abstract

A new approach for the generation of femtosecond and picosecond pulses is investigated using synchronous pumping of an optical parametric oscillator (OPO) by long, microsecond trains of picosecond excitation pulses. A mode- locked, feedback controlled Nd:glass or Nd:YLF laser with subsequent frequency doubling is used as a pump source (pulse duration 0.8 and 5.5 ps, repetition rate 7 and 70 Hz, respectively). The OPO cavity consists of a totally reflecting mirror, a partially reflecting output mirror and a lens to produce a beam waist in the nonlinear crystal. A noncollinear pumping scheme is chosen to ensure that only one of the two generated parametric components (signal or idler) is fed back in the cavity. Frequency tuning is achieved by rotating the crystal and readjusting the mirror positions to compensate for group velocity dispersion and beam displacement.

© 1992 IQEC