Abstract

We present two beam coupling experiments in aperovskite PbTiO₃ unpoled single crystal.^[1] The use of ~ 100 fs pulses with fluences in the range of hundreds of GW/cm² allows efficient excitation, at 620 nm, of at least two photon absorption (TPA) process. A temporal analysis leads to the evidence of a long lived process; its evolution as a function of pump fluence gives a better insight and a more accurate determination of parameters used to describe the general (at zero delay) behavior of this material with respect to intensity. In particular, balance between free carrier excitation by TPA and electrons produced by linear absorption from deep impurity level may be ascertained; furthermore, relative values of σ_e and σ_h, electron and hole cross sections, can be characterized more precisely. Comparison with BaTiO₃^[2] on one hand, and GaAs like semiconductors^[3] on the other hand are in this sense very instructive.

© 1992 IQEC