Coherent Optical Interactions in Semiconductors

The NATO Advanced Research Workshop on Coherent Optical Processes in Semiconductors was held in Cambridge, England on August 11-14,1993. The idea of holding this Workshop grew from the recent upsurge in activity on coherent transient effects in semiconductors. The development of this field reflects advances in both light sources and the quality of semiconductor structures, such that tunable optical pulses are now routinely available whose duration is shorter than the dephasing time for excitonic states in quantum wells. It was therefore no surprise to the organisers that as the programme developed, there emerged a heavy emphasis on time-resolved four-wave mixing, particularly in quantum wells. Nevertheless, other issues concerned with coherent effects ensured that several papers on related problems contributed some variety. The topics discussed at the workshop centred on what is a rather new field of study, and benefited enormously by having participants representing many of the principal groups working in this area. Several themes emerged through the invited contributions at the Workshop. One important development has been the careful examination of the two-level model of excitonic effects; a model which has been remarkably successful despite the expected complexities arising from the semiconductor band structure. Indeed, modest extensions to the two level model have been able to offer a useful account for some of the complicated polarisation dependence of four-wave mixing signals from GaAs quantum wells. This work clearly is leading to an improved understanding of excitons in confined systems.

Zusammenfassung
Proceedings of a NATO ARW held in Cambridge, United Kingdom, August 11-14, 1993

Inhalt
Optical Dephasing of Excitons in IIIV Semiconductors.- Coherent Excitonic and Free Carrier Dynamics in Bulk GaAs and Heterostructures.- Many-Body Theory of Coherent Optical Effects in Semiconductors.- Spin-Related Effects in IIIV Semiconductors.- Quantum Beat Spectroscopy of Excitons in Semiconductors.- Investigation of Free-Carrier Scattering in Semiconductors Using Coherent Spectroscopy.- Nonlinear Coherent Optical Effects in Semiconductors.- Non-Markovian Optical Systems.- Ultrashort Coherent Excitations in Semiconductors.- Vertical Transport Studied by Sub-Picosecond Four-Wave Mixing Experiments.- Amplitude Decay and Instantaneous Frequency Dynamics of Excitonic Polarization in Semiconductor Quantum Wells.- Dephasing Time Measurements in Quantum Dots by Non-Degenerate Four-Wave Mixing.- Coherence Effects on the Exciton Radiative Recombination in Quantum Wells.- The Relationship Between Real and Virtual Excitation Mechanisms for Nonlinear Refraction.- Resonant Rayleigh Scattering in Epitaxially Grown ZnSe1?xSx Layers.- Spectrally-Resolved Femtosecond-Four-Wave Mixing on Semiconductors.- Quantum Beats and Polarization Interference from Quantum Well Excitons.- Nature of Coherent Four-Wave Mixing Beats in Semiconductors.- Analogies Between Coherent Optical Interactions and Quantum Transport in Semiconductor Devices.- Optical Generation and Detection of Carriers in Ultrafast Pump-Probe Spectroscopy of Semiconductors.- Study of Exciton Dephasing in Superlattices using Resonant Raman Spectroscopy.- Bloch Oscillations in Superlattices.- Violation of Time-Reversibility in Semiconductors by Transient Optical Excitation.- Ultrafast Optical Generation of Carriers in a DC Electric Field.- Many-Body Effects at the Fermi Edge of Modulation-Doped Semiconductors: a NumericalStudy.- Theory of Polarization-Dependent Four-Wave Mixing in Quantum Wells using the Optical Bloch Equations.- Polarization Studies of Four-Wave Mixing in GaAs Quantum Wells.- Participants.