Two-photon absorption of Nd laser radiation in GaAs

Abstract

The two-photon absorption coefficient of GaAs at 1.32 μm is found to be 0.033 ± 0.015 cm/MW. This value was obtained from transmission measurements employing a Q-switched Nd–YAG laser and an improved theoretical analysis taking into account fluctuations and the Gaussian pulse shape. Evidence of thermal self-focusing was seen in samples with linear absorption coefficients of order 1 cm−1 or larger.