Formation of defects in a GaAs crystal under the action of picosecond laser radiation near the optical damage threshold

The nonlinear optical properties of a GaAs crystal are investigated by the z-scan method. An increase (by a factor of more than 10) in the concentration of defects was observed in the GaAs crystal subjected to long-term pulsed laser irradiation (more than 10⁴ pulses, τ = 35 ps, λ = 1.064 μm) near the optical damage threshold.