Two-photon-absorption signals from semiconductors for adaptive pulse compression

Abstract

Summary form only given. We show experimentally that two-photon absorption (TPA) in semiconductors is maximized by the shortest possible, bandwidth-limited laser pulse, unperturbed by non-trivial phase effects. Our experimental work demonstrates that TPA signals from semiconductors yield a reliable merit function for adaptive pulse compression since TPA is maximized by the shortest possible pulse. Reliable and accurate adaptive compression of broadband laser pulses has been achieved in photoluminescence experiments on CdS thin films and in photocurrent experiments on a GaAsP photodiode. For broadband pulses, TPA is an easy-to-implement alternative to second harmonic generation (SHG), which is routinely used for adaptive compression. In particular, TPA offers the advantage that it does not require phase-matching, which is difficult to achieve over a large bandwidth in SHG experiments. Moreover, using TPA in photodiodes, a very compact set-up is obtained.