The frequency dependence of the gain required to compensate for absorption is determined for a layered structure consisting of alternating absorbing and amplifying layers. It is shown that the fulfillment of the same conditions is required for the existence of a band structure consisting of alternating bands allowed and forbidden for optical radiation propagation in the frequency-wave vector parametric region. Conditions are found under which the gain required for compensation is smaller than thresholds for absolute (parasitic lasing) and convective (waveguide amplification of radiation) instabilities.

Discusses conclusions reached by A E Dubinov and D A Mytareva in their paper "Invisible cloaking of material bodies using the wave flow method" (Usp. Fiz. Nauk 180 475 (2010) [Phys. Usp. 53 455 (2010)]) on whether the perfect optical cloaking of material objects is possible.

Евгений Борисович Александров (к семидесятилетию со дня рождения), Алферов Ж.И., Андреев А.Ф., Багаев С.Н., Белянин В.Б., Варшалович Д.А., Гинзбург В.Л., Забродский А.Г., Запасский В.С., Каплянский А.А., Перель В.И., Розанов Н.Н., Сурис Р.А.

This paper analyzes localized invariable-form structures of electromagnetic radiation in vacuum and soliton-like light structures traveling superluminally in a nonlinear medium. Both types of structures are concluded to be unstable to small perturbations.

This paper presents a theoretical analysis of the effect of inhomogeneities of the incident radiation and of the system parameters on the main characteristics of dissipative optical solitons in a nonlinear interferometer. An exact solution of the equations for the field distribution in the presence of inhomogeneities of coherent incident radiation is obtained and analyzed for steady-state regimes. Inhomogeneities that are large by comparison with the width of the soliton and that do not substantially distort the characteristics of the soliton cause the soliton to move as a whole with a velocity proportional to the inhomogeneity gradient. The coefficient when there is a gradient is found analytically for the threshold type of optical nonlinearity. (C) 2002 Optical Society of America.

The formation of three-dimensional optical solitons in a transparent medium with a nonlinear refractive index is investigated theoretically. The damping rate of disturbances during soliton propagation is calculated analytically with consideration of the terms that are quadratic in the disturbances of the stationary soliton. It is shown chat such damping is nonexponential and that the damping rate decreases with decreasing disturbance energy. Numerical calculations of the disturbance damping rate, which permit determination of the length of the nonlinear medium needed for soliton formation. are performed for saturable nonlinearity of the refractive index. (C) 2000 The Optical Society of America. [S1070-9762(00)00604-7].

Within the framework of the approximate method of moments proposed earlier, we analyzed the interaction of a stable localized structure existing in a wide-aperture laser with nonlinear losses - the fundamental laser autosoliton - with smooth inhomogeneities of the cavity optical path length, radiation losses, and laser pump. A simplified ''mechanical'' equation of motion for the autosoliton center is derived, in which the ir?homogeneity appears as the sum of the potential force and the friction force, proportional to the velocity of the laser autosoliton.