Abstract

The carrier dynamics in GaAs following injection with femtosecond pulses above the band gap has been a topic of interest for several years.¹⁻⁵ Information on carrier scattering and thermalization has been obtained and recent Monte Carlo simulations have achieved some success at explaining these induced absorption measurements.^6,7 In the present work, we report the first femtosecond spectroscopic measurements of both the real part and the imaginary part of the carrier-induced nonlinear refractive index of GaAs. Our results are useful for the design of ultrafast devices using these optical nonlinearities and bring new knowledge on hot-carrier many-body effects. We focus on instantaneous band gap renormalization and plasma screening of electron-hole interactions in the 850-920-nm region, and on the short-lived resonance in the 580-750-nm region.

© 1991 Optical Society of America