FIBER-LASER-BASED FEMTOSECOND PARAMETRIC GENERATOR IN BULK PERIODICALLY POLED LINBO3

A diode-pumped system for optical parametric generation of wavelength- tunable femtosecond pulses is demonstrated. It comprises an Er-doped f iber mode-locked laser, a fiber chirped-pulse amplifier, and a bulk pe riodically poled LiNbO3 (PPLN) optical parametric generator. The param etric generator is pumped at 777 nm with frequency-doubled microjoule pulses from the fiber amplifier and produces 300-fs pulses tunable fro m 1 to 3 mu m with output energies up to similar to 200 nJ. Use of a P PLN nonlinear crystal substantially reduces the pump energies required for efficient parametric generation. Saturated single-pass parametric energy conversion of 38% (internal) has been achieved with only 220 n J of pump inside the crystal. A parametric generation threshold of 54 nJ is observed, and efficient parametric conversion is obtained with r epetition rates up to 200 kHz. (C) 1997 Optical Society of America