A. A. Lisyansky

Optical Tamm States in One-Dimensional Magnetophotonic Structures

We demonstrate the existence of a spectrally narrow localized surface state, the so-called optical Tamm state, at the interface between one-dimensional magnetophotonic and nonmagnetic photonic crystals. The state is spectrally located inside the photonic band gaps of each of the photonic crystals comprising this magnetophotonic structure. This state is associated with a sharp transmission peak through the sample and is responsible for the substantial enhancement of the Faraday rotation for the corresponding wavelength. The experimental results are in excellent agreement with the theoretical predictions.

Dipole response of spaser on an external optical wave

We find the conditions upon the amplitude and frequency of an external electromagnetic field at which the dipole moment of a Bergman-Stockman spaser oscillates in antiphase with the field. For these values of the amplitude and frequency the loss in metal nanoparticles is exactly compensated by the gain. This shows that spasers may be used as inclusions in designing lossless metamaterials.

Channel spaser: Coherent excitation of one-dimensional plasmons from quantum dots located along a linear channel

We show that net amplification of surface plasmons is achieved in channel in a metal plate due to nonradiative excitation by quantum dots. This makes possible lossless plasmon transmission lines in the channel as well as the amplification and generation of coherent surface plasmons. As an example, a ring channel spaser is considered.

Forced synchronization of spaser by an external optical wave

We demonstrate that when the frequency of the external field differs from the lasing frequency of an autonomous spaser, the spaser exhibits stochastic oscillations at low field intensity. The plasmon oscillations lock to the frequency of the external field only when the field amplitude exceeds a threshold value. We find a region of values of the external field amplitude and the frequency detuning (the Arnold tongue) for which the spaser synchronizes with the external wave.

Stationary behavior of a chain of interacting spasers

We show that depending on the values of the coupling constants, two different scenarios for the stationary behavior of a chain of interacting spasers may be realized: (1) all the spasers are synchronized and oscillate with a unique phase and (2) a nonlinear autowave travels along the chain. In the latter scenario, the traveling wave is harmonic, unlike excitations in other known nonlinear systems. Due to the nonlinear nature of the system, any initial distribution of spaser states evolves into one of these steady states.

Rabi oscillations in spasers during nonradiative plasmon excitation

In the approach to the stationary regime, a spaser exhibits complicated and highly nonlinear dynamics with anharmonic oscillations.1 We demonstrate that these oscillations are due to Rabi oscillations of the quantum dot in the field of the nanoparticle. We show that the oscillations may or may not arise dependent on the initial conditions.

Inverse Borrmann effect in photonic crystals

The Borrmann effect, which is related to the microscopic distribution of the electromagnetic field inside the primitive cell, is studied in photonic and magnetophotonic crystals. This effect, well-known in x-ray spectroscopy, is responsible for the enhancement or suppression of various linear and nonlinear optical effects when the incidence angle and/or the frequency change. It is shown that by design of the primitive cell this effect can be suppressed and even inverted.

Self-consistent approach for calculations of exciton binding energy in quantum wells

We introduce a computationally efficient approach to calculating the characteristics of excitons in quantum wells. In this approach we derive a system of self-consistent equations describing the motion of an electron-hole pair. The motion in the growth direction of the quantum well in this approach is separated from the in-plane motion, but each of them occurs in modified potentials found self-consistently. The approach is applied to shallow quantum wells, for which we obtained an analytical expression for the exciton binding energy and the ground state eigenfunction. Our results are in excellent agreement with standard variational calculations, but require greatly reduced computational effort.

Dynamics of the transient regime of spaser

The dynamics of the nonradiative excitation of plasmons in the surface plasmon amplifier by stimulated emission of radiation (spaser) that represents a two-level quantum dot in the vicinity of the metal (plasmon) nanoparticle is considered. It is demonstrated that the steady-state generation of spaser is preceded by the regime with the oscillations at the Rabi frequency in which the phase difference between the dipole moments and the direction of the energy flux from the quantum dot to the nanoparticle exhibit the sign alternation.

Effect of interwall surface roughness correlations on optical spectra of quantum well excitons

We extend a theory of well-width fluctuations for inhomogeneous exciton broadening in quantum wells by expressing the fluctuation of the width in terms of the statistical characteristics of the morphological roughnesses of each interface forming the well. This allows us to take into account a possibility of cross correlations between the interfaces. We show that these correlations strongly suppress a contribution of interface disorder to the inhomogeneous linewidths of excitons. We also demonstrate that the vertical cross correlations are crucial for explaining the variety of experimental data on the dependence of the linewidth upon thickness of the quantum well.