COHERENT OPTICAL-GENERATION OF NONEQUILIBRIUM ELECTRONS STUDIED VIA BAND-TO-ACCEPTOR LUMINESCENCE IN GAAS

Nonequilibrium electrons generated by coherent optical excitation of G aAs are studied in a wide range of carrier density. The electron distr ibution is monitored via spectrally resolved band-to-acceptor luminesc ence after continuous-wave, picosecond, or femtosecond laser excitatio n. Our data demonstrate that the coherent coupling between the laser r adiation and the interband polarization and its dephasing strongly inf luence the initial carrier distribution. The energetic width of carrie r generation is broadened due to rapid phase-breaking scattering event s during carrier generation. Theoretical results from a Monte Carlo so lution of the semiconductor Bloch equations including on the same kine tic level coherent and incoherent phenomena show that the broadening o f the electron distribution is introduced mainly in the generation pro cess whereas the recombination of electrons with hound holes makes a m inor contribution. The theoretical results are in quantitative agreeme nt with the experimental data.