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Next: Polezhaev Andrey A. and Goryachev Andrey Up: Book of Abstracts Previous: Peretochkin I.S.Zimnyakov D.A.

Petruskevicius R. and Kuprionis Z.

Nonlinear dynamics of self-diffraction
at leaky wave resonances

R. Petruskevicius and Z. Kuprionis
Institute of Physics,
A.Gostauto 12, Vilnius 2600, Lithuania

Conventionally, for degenerate two-wave mixing in a thin nonlinear film it is applied Raman-Nath self-diffraction approach. There are no instabilities in the behavior of induced dynamic grating. A new situation occurs when two-wave induced dynamic grating overlaps with leaky wave resonances in a thin periodically modulated film and Woods anomalies appear. Leaky wave resonances are related to excitation of surface polaritons or guided waves in the thin slab. These resonances give rise to enhancement of local field and all nonlinear processes at the surface. The self-diffraction of laser radiation on the dynamic grating at these resonances exhibits instabilities which are not considered previously. The goal of this report is to present results of study of these new phenomena.

We have developed a theory of self-diffraction at leaky wave resonances using coupled-mode approach. The steady state solutions of this problem are multistable. In particular, very interesting steady state bifurcations were obtained at double leaky wave resonances. It is possible to achieve an overlap of several bistability loops of different nature and to obtain a pitchfork bifurcation for symmetric wave illumination conditions. The dynamical solutions of this problem have shown variety of temporal behavior: relaxation to stacionars, self-pulsing, Ruelle-Takens-Newhousen route to chaos. Some initial experimental observations of self-diffraction at leaky wave resonances also are presented. The experiments were carried out with the tex2html_wrap_inline4090 cw and pulsed lasers on liquid crystal films and atmospheric ice films on cooled metal mirror.



Book of abstracts
ICND-96