Search results for "Exciton"
showing 10 items of 317 documents
Acoustically tunable photonic structures based on microcavity polaritons
2006
Abstract The interaction between surface acoustic waves (SAWs) with (Al,Ga)As microcavity polaritons results in the formation of a dynamic optical superlattice with folded light dispersion and energy stop bands when the lower polariton branch is predominantly of photonic character. For small detunings between the excitonic and optical cavity resonances, the SAW bleaches the polariton resonances through the efficient dissociation of the excitons by its piezoelectric field.
Random population model to explain the recombination dynamics in single InAs/GaAs quantum dots under selective optical pumping
2011
18 páginas, 3 tablas, 9 figuras.-- et al.
Decoherence of the Exciton and Decay of the Excitonic Polaron in Quantum Dots
2005
Bulk-phonon mechanisms of decoherence of an exciton confined in a quantum dot (QD) are considered in order to establish time limitations for the coherent control of the exciton with relevance to its application in quantum information processing. These are the formation and decay of the excitonic polaron. The estimations of characteristic dephasing times for the InAs/GaAs QD are discussed.
Formation of self-trapped excitons through stimulated recombination of radiation-induced primary defects in alkali halides
1998
Abstract A self-trapped exciton formation through photostimulated recombination of an F and an H center — the exciton-created primary defect pair, is proposed and experimentally examined in alkali halides at low temperatures.
Luminescence of a self-trapped exciton in GeO2 crystal
1993
Abstract The self-trapped exciton (STE) is discovered in the GeO2 crystal. A PL band at 2.5 eV with a strong Stokes shift is excited only in the fundamental absorption range of GeO2 crystal with the quantum yield about 0.4 and the decay time constant 800 ± 5 μs at 80 K. The PL thermal quenching occurs at 200 K with the energy about 0.25 eV and the frequency factor 107. At 4.5 K the PL decay kinetics splits into two components with time constants 270 μs and 8000 μs, which can be due to a triplet state split in the zero magnetic field. The STE in GeO2 is very similar to a STE in SiO2.
Two-LO-Phonon Resonant Raman Scattering in II-VI Semiconductors
1996
Recently, absolute values of socond-order Raman scattering efficiency have been measured around the E 0 and E 0 + Δ 0 critical points of several II-VI semiconductor compounds. The measurements were perfomed in the z(x,x)z backscattering configuration on (001) (ZnSe and ZnTe) and (110) (CdTe) surfaces. They show strong incoming and outgoing resonances around the baud gap and larger scattering efficiencies as compaered to III-V compounds. A theoretical model which includes excitons as intermediate states in the Raman process is shown to give a very good quantitative agreement between theory and experiment. Only a small discrepancy exists, while III-V compounds the discrepancies were close to …
Evaluation of the Strength of Coupling Between a Vibrational Exciton and a Specific Low Frequency Mode
1993
In Davydov’s theory, one dimensional sub-systems within molecular crystals may exhibit self-trapping of some high frequency phonons as these travel by dipole resonance interaction, due to coupling to some specific soft oscillation mode1
Different regimes of electronic coupling and their influence on exciton recombination in vertically stacked InAs/InP quantum wires
2006
8 páginas, 8 figuras.
Purcell-enhancement of the radiative PL decay in perylenediimides by coupling with silver nanoparticles into waveguide modes
2017
In this work, an interesting approach to enhance the coupling between excitons and plasmons is proposed by integrating highly luminescent perylenediimides (PDIs) and Ag metal nanoparticles (MNPs) in the core of a multilayer dielectric waveguide. The combination of the weak plasmonic coupling and the high scattering of MNPs gives rise to a significant improvement of the PDI photoluminescence and Purcell factor (PF) in forward-scattering geometry. Furthermore, when the PDI-MNP system is used as the core of a multilayer waveguide, a Purcell factor enhancement larger than 10 is observed, which is explained by an increase in the exciton-plasmon coupling under the light confinement in the wavegui…
Crystal excitation: survey of many-electron Hartree-Fock calculations of self-trapped excitons in insulating crystals
1992
To model successfully the diversity of electronic structure exhibited by excitons in alkali halides and in oxide materials, it is necessary to use a variety or combination of theoretical methods. In this review we restrict our discussion to the results of embedded quantum cluster calculations. By considering the results of such studies, it is possible to recognize the general similarities and differences in detail between the various exciton models in these materials.