10 mJ class femtosecond optical parametric amplifier for generating soft x-ray harmonics

Power scaling of an infrared (IR) parametric amplifier chain, pumped at 800 nm by a terawatt Ti:sapphire laser system has been reported. A total output energy exceeding 10 mJ with 40 fs pulse duration has been achieved in the IR region, which is the highest energy and peak power ever reported for an ultrafast optical parametric amplifier scheme. By applying the developed IR pulses to high-order harmonic generation, we have observed a significant cutoff extension compared to the case of 800 nm driving wavelength. This source suits as a driver laser for extending high-order harmonic photon energy into the kiloelectronvolts region. (C) 2008 American Institute of Physics.