Nonlinear optical studies and CO2 laser-induced melting of Zn-doped GaAs

Abstract

The absorption of CO2 laser radiation (λ = 10.6 μm) in p-type GaAs is dominated by direct free-hole transitions between states in the heavy- and light-hole bands. For laser intensities of the order of 10 MW/cm2 (pulse duration at FWHM = 70 nsec), the absorption coefficient of lightly Zn-doped GaAs begins to decrease with increasing laser intensity. The nonlinear transmission is found to be reasonably well described by an inhomogeneously broadened two-level model, where the saturation intensity has a value of ~20 MW/cm2 for light with a wavelength of 10.6μm.