Multi-photon excitation properties of CdSe quantum dots solutions and optical limiting behavior in infrared range
(Impact Factor: 3.49).
11/2007; 15(20):12818-33. DOI: 10.1364/OE.15.012818
Multi-photon absorption and excitation properties of CdSe quantum dots in hexane with different dot-sizes have been investigated. The two- and three-photon absorption (2PA and 3PA) coefficients were measured by using ~160-fs laser pulses at wavelengths of ~775-nm and ~1300-nm, respectively. The dependence of one-, two- and three-photon induced fluorescence spectra as well as their double-exponential decay on the dot-sizes was studied. Based on the fluorescence emission spectra and temporal decay constants for a given sample solution excited by one-, two-and three-photon absorption, it can be concluded that the transition pathways for fluorescence emission and decay under one-, two- and three-photon excitation are nearly identical. The optical power limiting capabilities based on 2PA and 3PA mechanisms are demonstrated separately. In addition, a saturation behavior of 3PA at ~1300 nm was observed.
Available from: Werner J Blau
- "The former can be further divided into multi-photon absorption (MPA), RSA and free-carrier absorption (FCA). Up to date, numerous inorganic and organic materials, such as phthalocyanines (O'Flaherty et al. 2003; de la Torre et al. 2004), porphyrins (Blau et al. 1985; Senge et al. 2007), organic dyes (He et al. 1995; He et al. 2008), metal nanoclusters (Sun et al. 1999; Wang et al. 2009), quantum dots (He et al. 2007), etc. have been found to possess OL response. Carbon-related nanomaterials are actually a main branch in the field of OL materials (Chen et al. 2007; Wang et al. 2009). "
Carbon Nanotubes - Synthesis, Characterization, Applications, 07/2011; , ISBN: 978-953-307-497-9
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ABSTRACT: Gain characteristics of injection lasers based on self-organized quantum dots (QD) were studied for two systems: InGaAs QDs in AlGaAs matrix on GaAs substrate and InAs QDs in an InGaAs matrix on an InP substrate. A ground to excited state transition was observed with increasing threshold gain. The current density of the model gain was calculated for the QD-on-GaAs and the QD-on-InP injection lasers. Two characteristic regions are observed in the dependences of the gain and the lasing wavelength on current density in both systems of QDs. These regions are attributed to the ground and excited state lasing in a QD array, respectively. Raising the current leads first to saturation of the QD ground state gain and then to a transition to lasing via excited states of QDs. The latter is characterized by three times higher gain saturation level. The higher the QD density, the higher both the transparency current density and also the gain saturation level.
Computer Engineering & Systems, 2008. ICCES 2008. International Conference on; 01/2008
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ABSTRACT: We report on large three-photon absorption (3PA) in thioglycol-capped ZnS semiconductor quantum dots (QDs) at different wavelengths with femtosecond Z-scan technique. Both the intrinsic 3PA coefficients and cross sections of the 1.3 nm sized ZnS QDs in aqueous solution are nearly one order of magnitude greater than that of ZnS bulk crystal. The 3PA resonance in ZnS QDs is observed at the lowest excitonic transition of 1S(e)-1S<sub>3/2</sub>(h) .
Applied Physics Letters 04/2008; 92(13-92):131114 - 131114-3. DOI:10.1063/1.2906904 · 3.30 Impact Factor
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