Exciton polaritons are considered in infinite multiple quantum wells which are periodic except that one well ~impurity! has a different well width from the others ~host!. Under certain circumstances it is possible to have a long-lived exciton-polariton mode localized about the impurity. From the viewpoint of the electromagnetic field, this corresponds to waveguide modes in the vicinity of an ex...

The standard theory of the Frenkel exciton (a small radius exciton) is applied to a fullerene 2D solid. It is the dipole collective electron excitation of a single cluster which forms the delocalized plasmon-Frenkel-exciton (PFE) in a crystal. The PFE retarded interaction is taken into account. We present transverse PFE-polariton dispersion curves along with the Coulomb problem solution for lon...

A model describing the dynamics of crystal exciton states on a hexagonal lattice has been studied in [1]. The hamiltonian includes terms describing the movement of the exciton throughout the crystal. Here we generalize the hamiltonian by including first order couplings of such terms to the lattice phonon fields. A discussion of the ground state configuration of the exciton field as a function o...

We investigate the nature of ultrafast exciton dissociation and carrier generation in acceptor-doped conjugated polymers. Using a combination of two-pulse femtosecond spectroscopy with photocurrent detection, we compare the exciton dissociation and geminate charge recombination dynamics in blends of two conjugated polymers, MeLPPP methyl-substituted ladder-type poly p-phenylene and MDMO-PPV pol...

We photoexcite slab polymer waveguides doped with J-aggregating dye molecules and measure the leaky emission from strongly coupled waveguide exciton polariton modes at room temperature. We show that the momentum of the waveguide exciton polaritons can be controlled by modifying the thickness of the excitonic waveguide. Nonresonantly pumped excitons in the slab excitonic waveguide decay into tra...

We have studied the response of excitons in a multiple quantum well structure under the presence of intense midinfrared fields. Peak fields (∼10 V/cm, in the plane of quantum wells) that would cause exciton quenching at low frequencies (up to ∼ GHz) are observed to have no significant quenching effect on the exciton resonance when applied at ∼100 THz. We attribute this lack of quenching to the ...

The emission spectrum of exciton complexes formed in individual self-assembled quantum dots (QDs) embedded into a p-n junction is theoretically studied using an effective mass model. We calculate the particle Coulomb interactions, eletronhole overlaps and transition energies of exciton complexes for the different strength and direction of electric field. Both redshifts and blueshifts are observ...

The dynamical aspects of the phonoriton state in highly-photoexcited semiconductors is studied theoretically. The effect of the exciton-exciton interaction and nonbosonic character of high-density excitons are taken into account. Using Green’s function method and within the Random Phase Approximation it is shown that the phonoriton dispersion and damping are very sensitive to the exciton densit...

We calculate the spectrum of elementary excitations in a two-dimensional exciton condensate in the vicinity of a two-dimensional electron gas. We show that attraction of excitons due to their scattering with free electrons may lead to formation of a roton minimum. The energy of this minimum may go below the ground state energy which manifests breaking of the superfluidity. The Berezinsky-Koster...

The superradiant decay rate and frequency shift of a Wannier exciton in a one-dimensional quantum wire are studied. It is shown that the dark mode exciton can be examined experimentally when the quantum wire is embedded in a planar microcavity. It is also found that the decay rate is greatly enhanced as the cavity length Lc is equal to the multiple wavelength of the emitted photon. Similar to i...