Optical Gain and Lasing in Semiconductor Nanocrystals

The broad spectral coverage for luminescence from the ultraviolet (UV) to the NIR offered via the tunability of composition, size and shape in semiconductor nanocrystals, presents an obvious advantage for the use of such materials as tunable optical gain media, and in laser applications. Furthermore, low lasing thresholds are predicted for QDs and quantum wires, compared with two-dimensionally confined quantum wells, form the basis of the present semiconductor diode laser devices which are ubiquitous in information and telecommunication technologies [86, 87]. 

Amplified spontaneous emission was recently observed by Bawendi, Klimov and coworkers for spherical colloidal CdSe QDs in close-packed films where pumping vhth an amplified femtosecond laser source was used to compete with fast non-radiative Auger decay processes [13, 88]. In further studies, films vhth CdSe nanocrystals were deposited on a distributed feed-back grating structure to yield optically pumped lasing that was tunable through the visible range by changing the nanocrystal size [89, 90]. 

Lasing was also observed for semiconductor nanocrystals in solution at room temperature, by using a cylindrical microcavity with nanosecond excitation. For this, a simple microcavity set-up was used which provided an uncomplicated means 

32 Dabbousi, B.O., Rodriguez-Viejo, J., Mikulec, F.V., Heine, J.R., Mattoussi, 

47 Steiner, D Dorft, D Banin, U Della Sala, F Manna, L and Millo, O. (2008) 

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