Optical experiments with subpicosecond pulses allow to investigate the initial relaxation of electrons in semiconductors. The standard Boltzmann equation is not able to describe properly the emission of longitudinal optical phonons. Rather, memory effects (non-Markovian behaviour) has to be taken into account. Within density matrix theory, kinetic equations are derived and solved which are valid up to fourth order in the interaction. For bulk GaAs, differential transmission spectra are measured in dependence on frequency and pump-probe delay. In agreement with the calculations, the observed initially broad phonon replica sharpen on a timescale of 100 fs, which evidences non-Markovian features in the electron-phonon scattering. For a proper line shape fit, the excitonic enhancement has to be taken into account.
© 1998 Optical Society of AmericaPDF Article
More Like This
QThA1 Quantum Electronics and Laser Science Conference (QELS) 1996
M.U. Wehner, M.H. Ulm, D.S. Chemla, and M. Wegener
QMD1 International Quantum Electronics Conference (IQEC) 1998
V. O. Lorenz and S. T. Cundiff
JThE113 Conference on Lasers and Electro-Optics (CLEO) 2005