title: Nanocrystals of PbSe core, PbSe/PbS, and PbSe/PbSxS(1-x) core/shell as saturable absorbers in passively Q-switched near-infrared lasers.
abstract: The saturable optical absorption properties of PbSe core nanocrystals (NCs), and their corresponding PbSe/PbScore/shell and PbSe/PbSexS(1-x) core/alloyed-shell NCs, were examined at lambda = 1.54 microm. Saturation intensities of approximately 100 MW/cm2 were obtained. The NCs act as passive Q switches in near-infrared pulsed lasers. Q-switched output pulse energies up to 3 mJ, with a pulse duration of 40-55 ns were demonstrated. Analysis of the optical transmission versus pulse light intensity was carried out according to a model that includes ground-state as well as excited-state absorption. For pulses approximately 10 ns long, the NCs act as fast saturable absorbers. The theoretical fits yield a ground-state absorption cross section of 10-16-10-15 cm2, an excited-state absorption cross section of sigma(es) is congruent to 10(-16) cm2, and an effective lifetime of tau(eff) is congruent to 5 x 10(-12) s.
authors.affiliation: Department of Chemistry, Solid State Institute, Haifa, Israel.
authors.forename: Maya
authors.initials: M
authors.lastname: Brumer
authors.forename: Marina
authors.initials: M
authors.lastname: Sirota
authors.forename: Ariel
authors.initials: A
authors.lastname: Kigel
authors.forename: Aldona
authors.initials: A
authors.lastname: Sashchiuk
authors.forename: Ehud
authors.initials: E
authors.lastname: Galun
authors.forename: Zeev
authors.initials: Z
authors.lastname: Burshtein
authors.forename: Efrat
authors.initials: E
authors.lastname: Lifshitz