Two-Photon Absorption and Photoconductivity in GaAs and InP

Abstract

Absorption and photoconductivity in GaAs and InP have been studied as functions of light intensity I up to 20 MW/cm2 at 1.06 μ. The two-photon-absorption coefficient is determined to be ≈ 0.3I cm−1 for n-GaAs and ≈ 0.2I cm−1 for n-InP. These values are much larger than that predicted by the existing theories. For the n-InP samples, the absorption by the two-photon-excited free carriers is found to be important, giving an absorption coefficient of ≈ 0.15I2 cm−1. From the photoconductivity measurements, the concentration and the absorption cross section of holes are determined.