Double-passed, High-energy Quasiphase-matched Optical Parametric Chirped-pulse Amplifier

Abstract

AbstractQuasiphase-matched (QPM) optical parametric chirped-pulse amplification (OPCPA) in periodically poled materials such as periodically poled LiNbO3 (PPLN) and periodically poled KTiOPO4 (PPKTP) has been shown to exhibit advantages over the OPCPA in bulk nonlinear crystals [1],[2]. The use of the maximum material nonlinear coefficient results in ultrahigh gain with low pump peak power. Furthermore, the propagation of signal, pump, and idler beams along one of the crystal principal axes eliminates the birefringent walk-off, reduces angular sensitivity, and improves beam quality. Relatively high level of parasitic parametric fluorescence (PF) in QPM OPCPA represents an impediment for simple, single-stage, high-gain amplification of optical pulses from nanojoules to millijoules energies. PF in QPM is increased when compared to PF in critical phase matching in bulk crystals due to broader angular acceptance of the nonlinear conversion process. The PF reduces prepulse contrast and conversion efficiency by competition with the signal pulse for pump pulse energy. Previous experiments with QPM OPCPA have thus resulted in pulse energies limited to tens of microjoules. [3] Optical parametric amplification of a narrowband signal pulse in PPKTP utilizing two pump beams has been demonstrated at a millijoule level [4], but the conversion efficiency has been limited by low energy extraction of pump pulse in the first pass of amplification. Additionally, narrow spectral bandwidth was the result of operation far from signal-idler degeneracy.KeywordsPump PulseOptical Parametric AmplificationPump Pulse EnergyIdle PulseCritical Phase MatchThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.