M. E. Raikh

Random resonators and prelocalized modes in disordered dielectric films.

We calculate the areal density of disorder-induced resonators with a high quality factor, Q>>1, in a film with fluctuating refraction index. We demonstrate that, for a given kl>1, where k is the light wave vector and l is the transport mean-free path, when on average the light propagation is diffusive, the likelihood for finding a random resonator increases dramatically with increasing the correlation radius of the disorder. Parameters of most probable resonators as functions of Q and kl are found.

Aharonov-Bohm effect for an exciton

We study theoretically the exciton absorption on a ring shreded by a magnetic flux. For the case when the attraction between electron and hole is short-ranged we get an exact solution of the problem. We demonstrate that, despite the electrical neutrality of the exciton, both the spectral position of the exciton peak in the absorption, and the corresponding oscillator strength oscillate with magnetic flux with a period

Anomalous Coherent Backscattering of Light from Opal Photonic Crystals

\Phi_0

Classical model for the negative dc conductivity of ac-driven two-dimensional electrons near the cyclotron resonance

---the universal flux quantum. The origin of the effect is the finite probability for electron and hole, created by a photon at the same point, to tunnel in the opposite directions and meet each other on the opposite side of the ring.

Photonic versus random lasing in opal single crystals

We studied coherent backscattering (CBS) of light from opal photonic crystals with incomplete band gaps. We observed a dramatic broadening of the CBS cone for incident angles close to the Bragg condition in the crystals. We modify the conventional CBS theory to incorporate Bragg attenuation resulting from the photonic band structure. By fitting the CBS data with the modified theory, we extract both the disorder-induced light mean-free path and the Bragg attenuation length of the inherent opal photonic crystal.

Exchange-induced enhancement of spin-orbit coupling in two-dimensional electronic systems

A classical model for dc transport of two-dimensional electrons in a perpendicular magnetic field and under strong irradiation is considered. We demonstrate that, near the cyclotron resonance condition, and for linear polarization of the ac field, a strong change of the diagonal component, σ d , of the dc conductivity occurs in the presence of a weak nonparabolicity of the electron spectrum. Small change in the electron effective mass due to irradiation can lead to negative σ d , while the Hall component of the dc conductivity remains practically unchanged. Within the model considered, the sign of σ d depends on the relative orientation of the dc and ac fields, the sign of the detuning of the ac frequency from the cyclotron resonance, and the sign of nonparabolic term in the energy spectrum. We also demonstrate that the known phenomenon of the nonparabolicity-induced hysteresis in the cyclotron absorption manifests itself in the dc transport by causing a hysteresis in the magnetic-field dependence of σ d .

Pair Tunneling through Single Molecules.

We demonstrate a photopumped photonic crystal laser based on synthetic opal single crystal infiltrated with various laser dye solutions. The optical feedback in these lasers is provided via Bragg scattering of light from crystallographic planes in the opal. Localization of the laser modes within the stop band is assigned to defect states caused by crystal structure faults. We distinguish this photonic lasing mechanism from another regime of stimulated emission associated with random lasing what could be also observed in dye-infiltrated opals, but at higher excitation intensities.

Universal properties of random lasers

We study theoretically the renormalization of the spin-orbit coupling constant of two-dimensional electrons by electron-electron interactions. We demonstrate that, similarly to the

Evidence for braggoriton excitations in opal photonic crystals infiltrated with highly polarizable dyes

g

LOCALIZATION AND CONDUCTANCE FLUCTUATIONS IN THE INTEGER QUANTUM HALL EFFECT : REAL-SPACE RENORMALIZATION-GROUP APPROACH

factor, the renormalization corresponds to the enhancement, although the magnitude of the enhancement is weaker than that for the