Subpicosecond excitonic optical nonlinearities in quantum wells
Résumé
Excitonic resonances in semiconductors are very sensitive to applied optical fields. We present here a comparison between the effects of resonant and non resonant optical excitation, creating respectively real or virtual excitons. A blue shift of the exciton line and a reduction of the oscillator strength are simultaneously observed in multiple-quantum-well-structures for the two following cases : presence of a population of real excitons in very thin wells (two-dimensional systems), or presence of an intense offresonance non absorbed optical field (virtual excitons) independently of the well thickness. The latter configuration (optical Stark effect) has been studied as a function of pump intensity, determining in particular how the saturation of the blue shift is related to the exciton bleaching.
Mots clés
excitons
nonlinear optics
oscillator strengths
semiconductor superlattices
spectral line shift
Stark effect
subpicosecond excitonic optical nonlinearities
excitonic resonances
real excitons
nonresonant optical excitation
exciton line blue shift
oscillator strength reduction
nonabsorbed optical field
quantum wells
resonant optical excitation
virtual excitons
multiple quantum well structures
well thickness
optical Stark effect
pump intensity
exciton bleaching
Domaines
Articles anciens| Origine | Accord explicite pour ce dépôt |
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