Femtosecond optical parametric amplifier generates millijoule pulses

Scientists at Fudan University (Shanghai, China) and the National Center for High Power Lasers (Mianyang, China) have developed a femtosecond optical parametric amplifier (OPA) that emits at the millijoule-level-an order of magnitude higher than existing femtosecond OPAs. The device may provide a feasible alternative to optical parametric chirped-pulse amplifiers.

The emitter is pumped by a terawatt femtosecond Ti:sapphire laser system operating at 800 nm and a repetition rate of 10 Hz. A small portion of the pump pulse generates supercontinuum white light in a 5-mm-thick sapphire plate, which is used to seed the amplifier consisting of two type-I phase-matched lithium niobate crystals (uncoated), both with dimensions of 60 × 60 × 15 mm. Pulse energy of 4 mJ at 1053 nm with a duration of less than 100 fs is obtained at a pump pulse energy of 80 mJ, which corresponds to a total conversion efficiency of 6.5% (signal plus idler). The generated millijoule-level pulse may be stretched to about 4 ns by a large-aperture grating, such as one soon to be installed in an Nd:glass chirped-pulse booster amplifier system. The facility will deliver synchronized high-power femtosecond pulses at 800 nm and 1053 nm that may find many applications in diverse areas of research. Contact Liejia Qian at ljqian@fudan.edu.cn.