51 research outputs found
All optical Amplification in Metallic Subwavelength Linear Waveguides
Proposed all optical amplification scenario is based on the properties of
light propagation in two coupled subwavelength metallic slab waveguides where
for particular choice of waveguide parameters two propagating (symmetric) and
non-propagating (antisymmetric) eigenmodes coexist. For such a setup incident
beams realize boundary conditions for forming a stationary state as a
superposition of mentioned eigenmodes. It is shown both analytically and
numerically that amplification rate in this completely linear mechanism
diverges for small signal values.Comment: 5 pages 2 figure
Negative refraction and spatial echo in optical waveguide arrays
The special symmetry properties of the discrete nonlinear Schrodinger
equation allow a complete revival of the initial wavefunction. That is employed
in the context of stationary propagation of light in a waveguide array. As an
inverting system we propose a short array of almost isolated waveguides which
cause a relative pi phase shift in the neighboring waveguides. By means of
numerical simulations of the model equations we demonstrate a novel mechanism
for the negative refraction of spatial solitons.Comment: 3 pages, 2 figure
Trapping of Nonlinear Gravitational Waves by Two-Fluid Systems
We show that the coupled two-fluid gravitating system (e.g. stiff matter and
'vacuum energy') could trap nonlinear gravitational waves (e.g. Einstein-Rosen
waves). The gravitational wave amplitude varies harmonically in time
transferring the energy coherently to the stiff matter wave, and then the
process goes to the backward direction. This process mimics the behaviour of
trapped electromagnetic waves in two-level media. We have defined the limits
for the frequency of this energy transfer oscillations.Comment: 8 pages, the version accepted by Mod. Phys. Lett.
Coexistence of Josephson oscillations and novel self-trapping regime in optical waveguide arrays
Considering the coherent nonlinear dynamics between two weakly linked optical
waveguide arrays, we find the first example of coexistence of Josephson
oscillations with a novel self-trapping regime. This macroscopic bistability is
explained by proving analytically the simultaneous existence of symmetric,
antisymmetric and asymmetric stationary solutions of the associated
Gross-Pitaevskii equation. The effect is, moreover, illustrated and confirmed
by numerical simulations. This property allows to conceive an optical switch
based on the variation of the refractive index of the linking central
waveguide.Comment: 4 pages, 4 figure
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