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1997
Journal Article
Title
Ultrafast coherent carrier control in quantum wells
Other Title
Kontrolle ultraschneller kohärenter Ladungsträger in Quantum Wells
Abstract
A fast scanning ultrafast phase-dependent reflectivity technique is used to measure the coherent properties of multiple quantum wells at carrier densities below 108 cm (exp -2). Signal to noise ratios in the reflected intensity >80 dB can be achieved allowing underlying coherences to be measured at time delays beyond 30 ps. An unexpected 1.5 ps rise time of the coherence is resolved before a non-exponential decay and ascribed to interference of polaritons. By time-resolving the pair of pulses reflected off the sample, a complete history of energy flow in the quantum wells can be identified. Both spontaneous and stimulated coherent reemission are observed in good agreement with models based on the Bloch equations.
Author(s)