Theory of Optically Nonlinear Effects in Ultrafast Spatio-Temporal Dynamics of Semiconductors

Abstract

Recently, the dynamics of excitons, biexcitons and the electron-hole plasma after excitation with femtosecond light pulses (1 fs = 10 -15 s) in semiconductor microand nanostructures has been studied extensively [1, 2]. Coherent nonlinear effects such as the optical Stark-effect, four-wave mixing (FWM), photon echoes, and Rabi oscillations have been observed [3]. Whereas the linear optical susceptibility is dominated by electron-hole Coulomb (exciton) effects, at moderate intensities, biexcitons may form and carrier-carrier scattering takes place for the excitation of continuum states. For sufficiently high electron-hole densities in a semiconductor, negative absorption, i.e., optical gain appears [4]. The purpose of this paper is to give a short introduction in the theoretical treatment of spatiotemporal effects in semiconductor optics and to review some recent results. Our analysis includes light propagation effects in optically thick samples as well as optically induced electron and exciton transport.