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

Self-Chaotization in Coupled Optical Waveguides

We consider theoretically two coupled optical waveguides with a varying barrier height along the waveguides direction. The barrier could be constructed by the elongated island with a reduced refractive index (which acts as a potential barrier), such that in the middle region it splits a waveguide into two weakly coupled parts. It is predicted by numerical simulations and analytical consideration that the presence of some imperfection of the system parameters can cause splitting of injected laser beam and one will observe two intensity maximums at the output, while for small imperfections the input and output beam intensity distributions will be the same. The switching between two regimes could be achieved changing spectral width of the beam or refractive index of the island. This nontrivial effect is explained by possibility of transitions between the different eigenstates of the system in the region of large potential barrier heights. The mentioned effect could be used for all-optical readdressing and filtering purposes

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.