Abstract

Pulses of 65-fs duration, 5-μJ energy, and 8-kHz repetition rate are generated from a copper vapor laser amplified CPM dye laser. A small fraction of the pulse is split off as a pump beam (hν = 1.99 eV), and the remainder is used to generate a white light continuum which is filtered to provide a probe beam at the selected photon energy. The two GaAs samples (0.34 and 0.3 μm thick) are obtained using the lift-off procedure of Yablonovitch et al.¹ and mounted on glass and sapphire windows. The time-resolved transmission T and reflection R at room temperature are measured at various probe photon energies, especially from 1.46 to 1.38 eV and at carrier densities N from 10¹⁷ to 10¹⁹ cm⁻³. Typical time-resolved changes of the absorption coefficient derived from T and R are shown in Fig. 1.

© 1990 Optical Society of America