1,504 research outputs found
Transverse Patterns in Nonlinear Optical Resonators
The book is devoted to the formation and dynamics of localized structures
(vortices, solitons) and extended patterns (stripes, hexagons, tilted waves) in
nonlinear optical resonators such as lasers, optical parametric oscillators,
and photorefractive oscillators. The theoretical analysis is performed by
deriving order parameter equations, and also through numerical integration of
microscopic models of the systems under investigation. Experimental
observations, and possible technological implementations of transverse optical
patterns are also discussed. A comparison with patterns found in other
nonlinear systems, i.e. chemical, biological, and hydrodynamical systems, is
given. This article contains the table of contents and the introductory chapter
of the book.Comment: 37 pages, 14 figures. Table of contents and introductory chapter of
the boo
Bistable and dynamic states of parametrically excited ultrasound in a fluid-filled cavity
In this paper we have considered the problem of parametric sound generation
in an acoustic resonator flled with a fluid, taking explicitely into account
the influence of the nonlinearly generated second harmonic. A simple model is
presented, and its stationary solutions obtained. The main feature of these
solutions is the appearance of bistable states of the fundamental field
resulting from the coupling to the second harmonic. An experimental setup was
designed to check the predictions of the theory. The results are consistent
with the predicted values for the mode amplitudes and parametric thresholds. At
higher driving values a self-modulation of the amplitudes is observed. We
identify this phenomenon with a secondary instability previously reported in
the frame of the theoretical model.Comment: 5 figures. Submitted to JAS
Ultrasonic cavity solitons
We report on a new type of localized structure, an ultrasonic cavity soliton,
supported by large aspect-ratio acoustic resonators containing viscous media.
The spatio-temporal dynamics of this system is analyzed on the basis of a
generalized Swift-Hohenberg equation, derived from the microscopic equations
under conditions close to nascent bistability. These states of the acoustic and
thermal fields are robust structures, existing whenever a spatially uniform
solution and a periodic pattern coexist. An analytical solution for the
ultrasonic cavity soliton is also presented
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