Abstract

Pulses of 100-fs duration, 2-μJ energy, and at a repetition rate of 8 kHz are generated from a copper vapor laser amplified CPM dye laser. A small fraction of the pulse is split off as a pump beam and the remainder is used to generate a white light continuum as a probe beam. The sample is a 0.15-μm thick GaAs film obtained using the lift-off procedure of Yablonovitch et al.¹ We report time resolved transmission measurements at probe photon energies from 1.38 to 2.07 eV and carrier densities from 10¹⁷ to 10¹⁹ cm^-3. Earlier work was restricted to a carrier density of ~10¹⁸ cm^-3 and probe photon energy above the bandgap.² Different hot carrier processes, such as carrier-carrier scattering, carrier-phonon scattering, state filling, and bandgap renormalization, and their dependence on carrier density are discussed.

© 1989 Optical Society of America