Two-photon absorption of neodymium laser radiation in gallium arsenide

We have studied the interaction of picosecond pulses from a Nd : glass laser with GaAs. The experimental data at incident powers up to ∼30 GW/cm2 can be satisfactorily explained in terms of two-photon absorption with β=0.015±0.005 cm/MW. The results are discussed in connection with the discrepancies existing in the literature about the experimental values of β. Their implications for the existence of self-induced transparency effects in GaAs are also briefly pointed out.