Efficient femtosecond traveling-wave optical parametric amplification in periodically poled KTiOPO4

Abstract

We report, for the first time to our knowledge, high-power femtosecond traveling-wave optical parametric amplification by use of periodically poled KTiOPO4. With a single pass through a 4-mm-long sample of 1.23-mm thickness we achieved 40% internal conversion efficiency and 5 mu J of single-pulse idler energy near 3.8 mu m, using only 75 mu J of energy from the output of a conventional 1-kHz Ti-sapphire regenerative amplifier. The 210-fs-long idler pulses were almost transform limited. We discuss the specific problems encountered in high-power parametric conversion, mich as unwanted quasi-phase-matched upconversion processes for polarization configurations that utilize the largest (d(38)) nonlinear coefficient and the related formation of color centers (gray tracking) in KTiOPO4. (C) 1999 Optical Society of America OCIS codes: 190.4970, 190.7110, 320.7110, 190.2620, 190.4400, 160.4330