Bragg Reflection Waveguide: Anti-Mirror Reflection and Light Slowdown

The effect of the light group velocity reduction in dielectric Bragg reflection waveguide structures (SiO$_2$/TiO$_2$) in the vicinity of the cutoff frequency is studied experimentally. The effect of anti-mirror reflection, specific for the Bragg reflection waveguides, is described and employed for detection of "slow light". The experiments were performed with the use of the Ti:sapphire laser pulses ~ 100 fs in length. The group index $n_g \sim$ 30 with a fractional pulse delay (normalized to the pulse width) of $\sim$ 10 is demonstrated. The problems and prospects of implementation of the slow-light devices based on the Bragg reflection waveguide structures are discussed.Comment: 11 pages, in the previous version, we failed to insert figure

Low-temperature kinetics of exciton-exciton annihilation of weakly localized one-dimensional Frenkel excitons

We present results of numerical simulations of the kinetics of exciton-exciton annihilation of weakly localized one-dimensional Frenkel excitons at low temperatures. We find that the kinetics is represented by two well-distinguished components: a fast short-time decay and a very slow long-time tail. The former arises from excitons that initially reside in states belonging to the same localization segment of the chain, while the slow component is caused by excitons created on different localization segments. We show that the usual bi-molecular theory fails in the description of the behavior found. We also present a qualitative analytical explanation of the non-exponential behavior observed in both the short- and the long-time decay components.Comment: Published in J. Chem. Phys. 114, 1 April (2001

Cooper pairing of electrons and holes in graphene bilayer: Correlation effects

Cooper pairing of spatially separated electrons and holes in graphene bilayer is studied beyond the mean-field approximation. Suppression of the screening at large distances, caused by appearance of the gap, is considered self-consistently. A mutual positive feedback between appearance of the gap and enlargement of the interaction leads to a sharp transition to correlated state with greatly increased gap above some critical value of the coupling strength. At coupling strength below the critical, this correlation effect increases the gap approximately by a factor of two. The maximal coupling strength achievable in experiments is close to the critical value. This indicated importance of correlation effects in closely-spaced graphene bilayers at weak substrate dielectric screening. Another effect beyond mean-field approximation considered is an influence of vertex corrections on the pairing, which is shown to be very weak.Comment: 6 pages, 5 figures; some references were adde

Two Detector Reactor Neutrino Oscillation Experiment Kr2Det at Krasnoyarsk. Status Report

We consider status of the Kr2Det project aimed at sensitive searches for neutrino oscillations in the atmospheric neutrino mass parameter region around Dm2 ~ 3x10-3 eV2and at obtaining new information on the electron neutrino mass structure (Ue3).Comment: 4 pages in pdf file. Talk presented at NANP-2001 International Conference in Dubna, Russia, June 200

Antineutrino-Deuteron Experiment at Krasnoyrsk

This report is represented the results of some experiments, which carried out at the neutrino underground laboratory of Kranoyarsk nuclear plant.Comment: 8 pages, 3 figure