Stability of narrow beams in bulk Kerr-type nonlinear media

We consider (2+1)-dimensional beams, whose transverse size may be comparable to or smaller than the carrier wavelength, on the basis of an extended version of the nonlinear Schr\"{o}dinger equation derived from the Maxwell`s equations. As this equation is very cumbersome, we also study, in parallel to it, its simplified version which keeps the most essential term: the term which accounts for the {\it nonlinear diffraction}. The full equation additionally includes terms generated by a deviation from the paraxial approximation and by a longitudinal electric-field component in the beam. Solitary-wave stationary solutions to both the full and simplified equations are found, treating the terms which modify the nonlinear Schr\"{o}dinger equation as perturbations. Within the framework of the perturbative approach, a conserved power of the beam is obtained in an explicit form. It is found that the nonlinear diffraction affects stationary beams much stronger than nonparaxiality and longitudinal field. Stability of the beams is directly tested by simulating the simplified equation, with initial configurations taken as predicted by the perturbation theory. The numerically generated solitary beams are always stable and never start to collapse, although they display periodic internal vibrations, whose amplitude decreases with the increase of the beam power.Comment: 7 pages, 6 figures Accepted for publication in PR

DEVELOPMENT OF METHODS FOR LASER HYPERDOPING OF MATERIALS

The principle of laser doping consists in laser irradiation of a thin titanium layer deposited on the surface of a lithium niobate. When the metal melts, most of the heat is transferred to the inner surface of the plate, which leads to the formation of mixed molten layers of crystal and titanium.При выполнении работы использовалось оборудование Уральского Центра Коллективного Пользования «Современные нанотехнологии» УрФУ

SECOND ORDER HARMONIC SURFACE WAVES GENERATED BY ONE FUNDAMENTAL WAVE

No abstract availabl

Effective area of the LP01 mode in non-linear optical fibres

Recent investigations on the nonlinear dispersion law and the nonlinear wavenumber shift of the LP01 mode in step-index optical waveguides are extended to determining the effective area of the mode. The obtained result differs from that conventionally used and defines more precisely the characteristics of the nonlinear effects of self-phase modulation and soliton formation

Experiments on the nonlinear evolution of surface waves in an open plasma waveguide

The nonlinear behaviour of surface waves propagating along a plasma column is investigated. The experiments include (i) measurements of the nonlinear dispersion of the waves and (ii) observation of the evolution of the shape of the wave envelope and of the wave spectrum when the waves are excited with an amplitude-modulated signal. Comparison with theory shows that (i) the measured nonlinear wavelength shift corresponds to increasing wave phase velocity with increasing wave amplitude, (ii) the observed narrowing of the wave envelope can be associated with the formation of periodic nonlinear waves described by dn Jacobi elliptic function solutions of the nonlinear Schrodinger equation and (iii) the observed strong changes of the wave spectrum are mainly related to a nonlinear effect of phase modulation