We report efficient generation of tunable femtosecond pulses in the red by internal frequency doubling of an optical parametric oscillator (OPO) based on periodically poled (PPLN). The OPO, based on a 1-mm-thick PPLN crystal, is synchronously pumped by a femtosecond Ti:sapphire laser at , providing signal pulses across at a repetition rate. Using a 1-mm-thick crystal of (BIBO) internal to the OPO cavity, we achieve frequency doubling of signal pulses across with up to of average power for of pump. The high nonlinear gain and phase-matching acceptance in PPLN and BIBO permit convenient tuning across the full range by simple detuning of OPO cavity delay. Intracavity dispersion compensation results in near-transform-limited red pulses with durations down to for input pump pulses.
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