A. M. Samson

Rotating elliptical gaussian beams in nonlinear media

Abstract An analytical treatment of rotating elliptical gaussian beam propagation in nonlinear media is presented. It is shown that the self-focusing threshold depends on the parameter specifying the beam rotation and is higher than for the beam without rotation. It is established by the following rule: the greater the difference between the light beam and the axially symmetric one, the higher the threshold power needed for its self-focusing.

Ermakov Hamiltonian systems in nonlinear optics of elliptic Gaussian beams

Abstract It is shown that the systems of equations describing the propagation of elliptic Gaussian beams in a nonlinear medium are Ermakov Hamiltonian systems. It is demonstrated that these systems are completely integrable. The condition under which any Ermakov system is also a Hamiltonian system is determined.

Self-focusing of two orthogonally polarized light beams in a nonlinear medium

The propagation of two light beams with orthogonal polarization in a nonlinear medium is considered. It is shown that because of the interaction of the beams there are two different self-focusing regimes: monotonous and oscillatory. Analytical results are confirmed by computer simulation.

Induced superradiance in a thin film of two-level atoms

Abstract The transmission and reflection of a thin film of inverted two-level atoms is investigated numerically and analytically. The case of normal incidence of rectangular and secanthyperbolic-shape pulses is considered. It is shown, that the induced superradiance effect occurs due to the initial excited-state atoms. The time dependence of the transmitted and reflected pulses has been found.

Targeting unstable orbits and steady states in class-B lasers by using simple off/on manipulations

Abstract We have investigated transient dynamics under Q -switching from the off-state to the generalised multistability domain in models for lasers with modulated parameters and a saturable absorber in the context of possible applications for targeting unstable states. The main point of this method is the preparation of the laser in the special initial conditions which are close to both a trivial nonlasing state and a stable manifold of an unstable lasing state to be targeted. We show numerically that the latter conditions may be met in these lasers using simple step-wise Q -switching off/on manipulations.

Delay instabilities in light transmission of thin film with mirror

Spatio-temporal instabilities in a system formed by a thin film of two-level medium and a feedback mirror are theoretically investigated. Two mechanisms of delay instabilities connected with an interplay of the superradiance, the local field correction and the nutation oscillations are classified. The dependence of the dynamics on the ratio of the relaxation times to the delay is revealed. Influence of the delay on the threshold of spatial instability is elucidated.

Spontaneous patterns formation in thin film of two-level centers with a wide-aperture optical feedback

Abstract We present a thin film of two-level centers with a feedback mirror as a new object for a spontaneous formation of hexagon patterns, which can be perturbed by lattice penta-hepta defects. A spontaneous switching between two bistable states, initiated by a patterns formation, is detected.

Map limit dynamics of a chain of optically bistable thin films

Abstract The light dynamics of a bistable thin film chain is theoretically considered. The steady states of the system are found. In the limit of short relaxation times, the system demonstrates self-pulsation regimes (the flip-flop operation). The mechanism of pulsations and the possibility of experimental realization are briefly discussed.

Spatio-Temporal Light Structures in a Chain of Bistable Two-level Medium Thin Films

Abstract The light transmission through a system of bistable thin films of two-level atoms (centres) is considered. In the limit of an inertialess two-level medium, the problem is reduced to a nonlinear infinite-dimension mapping. It is shown that self-pulsation regimes occur when the incident light intensity is not enough to switch all bistable elements into the upper state. For the Gaussian incident beam, spatio-temporal light structures are studied. The structure of the transverse profile of the light beam depends to a large extent on the strength of diffraction, the increase of which leads to formation of smoother profiles, and regimes with a shorter period. Multistability of spatial structures is also investigated.

Instabilities and chaos in a bistable thin film of two-level atoms

Abstract The interaction of a modulated light signal with a bistable thin film of two-level atoms has been investigated. The regimes of chaotic response appearing by the Feigenbaum scenario have been found numerically. Possible manifestations of these effects in practical devices are discussed.