Fiber-laser-based femtosecond parametric generator in bulk periodically poled LiNbO_3

Abstract

A diode-pumped system for optical parametric generation of wavelength-tunable femtosecond pulses is demonstrated. It comprises an Er-doped fiber mode-locked laser, a fiber chirped-pulse amplifier, and a bulk periodically poled LiNbO(3) (PPLN) optical parametric generator. The parametric generator is pumped at 777 nm with frequency-doubled microjoule pulses from the fiber amplifier and produces 300-fs pulses tunable from 1 to 3microm with output energies up to ~200 nJ. Use of a PPLN 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 nJ of pump inside the crystal. A parametric generation threshold of 54 nJ is observed, and efficient parametric conversion is obtained with repetition rates up to 200 kHz.