"[68D140A2207C]" . "10.1103/PhysRevB.84.085321" . "Pelant, Ivan" . . "\u017D\u00EDdek, Karel" . "RIV/68378271:_____/11:00373625" . . "Little, R." . "000294326200011" . "236662" . "Detailed study of ultrafast stimulated emission arising from efficient quasidirect transitions in silicon nanocrystals under femtosecond pumping. In nanometer-sized silicon nanocrystals, the quasidirect transitions are rapidly cut off (on subpicosecond time scale) owing to surface trapping of carriers. Consequently, also the core-related radiative recombination undergoes ultrafast decay. We propose, theoretically describe, and experimentally demonstrate an extension of the commonly used variable stripe length (VSL) method, which enables us to measure transient stimulated emission even on the subpicosecond time scale. By applying the extended VSL method we reveal the presence of room-temperature transient optical gain in silicon nanocrystals (lifetime <1 ps) at wavelengths 590 nm with peak values of the order of 100 cm1. Finally, on the basis of our results we discuss possible ways of obtaining a laser source based on silicon nanocrystals."@en . . "Ultrafast stimulated emission due to quasidirect transitions in silicon nanocrystals"@en . "84" . . "\u0160iller, L." . "silicon nanocrystals; optical gain; fast radiative recombination"@en . . "Detailed study of ultrafast stimulated emission arising from efficient quasidirect transitions in silicon nanocrystals under femtosecond pumping. In nanometer-sized silicon nanocrystals, the quasidirect transitions are rapidly cut off (on subpicosecond time scale) owing to surface trapping of carriers. Consequently, also the core-related radiative recombination undergoes ultrafast decay. We propose, theoretically describe, and experimentally demonstrate an extension of the commonly used variable stripe length (VSL) method, which enables us to measure transient stimulated emission even on the subpicosecond time scale. By applying the extended VSL method we reveal the presence of room-temperature transient optical gain in silicon nanocrystals (lifetime <1 ps) at wavelengths 590 nm with peak values of the order of 100 cm1. Finally, on the basis of our results we discuss possible ways of obtaining a laser source based on silicon nanocrystals." . "Oberl\u00E9, J." . "P(IAA101120804), P(KAN400100701), P(LC510), S, Z(AV0Z10100521), Z(MSM0021620834)" . "Ultrafast stimulated emission due to quasidirect transitions in silicon nanocrystals" . "1098-0121" . "Ultrafast stimulated emission due to quasidirect transitions in silicon nanocrystals" . "Gilliot, P." . . "Horrocks, B. R." . "Troj\u00E1nek, F." . . . . "Mal\u00FD, P." . "9"^^ . . . . "8" . "2"^^ . . . . . "US - Spojen\u00E9 st\u00E1ty americk\u00E9" . "H\u00F6nerlage, B." . . . . "10"^^ . . . . "RIV/68378271:_____/11:00373625!RIV12-AV0-68378271" . . "Physical Review. B" . "Ultrafast stimulated emission due to quasidirect transitions in silicon nanocrystals"@en .