Investigation of Femtosecond IR Radiation Two-Photon Absorption by Pump-Probe Method in GaAs (001) Plate Reflection

Abstract

The reflection of probe infrared femtosecond radiation pulses from a gallium arsenide substrate of the (001) orientation in the presence of more powerful pump pulses of the same radiation with a peak power of up to 1 GW/cm² was investigated. A Yb³⁺:KY(WO4)2 laser with a central wavelength of 1 035 nm, a repetition rate of 70 MHz, a pulse duration of 130 fs, and an average power of not more than 0.9 W worked in the GaAs transparency region. The experimental dependence of the recorded signal on the pump radiation intensity is in qualitative agreement with the model dependence for two-photon absorption. The results are important for the correct interpretation of reflectivity kinetics of quantum wells.