DEPHASING IN THE GAIN REGION OF II-VI SEMICONDUCTOR NANOCRYSTALS

We investigate the dephasing times in highly excited CdSe and CdS0.3Se 0.7 nanocrystals by spectral hole burning throughout the gain region. The energy dependence of the phasing time T-2 is compared between quan tum dots in the strong-confinement regime and bulklike microcrystals. T-2 in strongly confined quantum dots remains rather constant, whereas the bulklike sample shows a continuous increase of T-2 toward the tra nsparency point. This observation is attributed to the different gain mechanisms in the strong and the weak quantum-confinement regimes. (C) 1996 Optical Society of America.