Parity-time-symmetric solitons in trapped Bose-Einstein condensates and the influence of varying complex potentials: A variational approach.

Dynamics and properties of nonlinear matter waves in a trapped BEC subject to a PT-symmetric linear potential, with the trap in the form of a super-Gaussian potential, are investigated via a variational approach accounting for the complex nature of the soliton. In the process, we address how the shape of the imaginary part of the potential, that is, a gain-loss mechanism, affects the self-localization and the stability of the condensate. Variational results are found to be in good agreement with full numerical simulations for predicting the shape, width, and chemical potential of the condensate until the PT breaking point.

Self-written waveguide in methylene blue sensitized poly(vinyl alcohol)/acrylamide photopolymer material.

We report the observation of a self-written waveguide inside a bulk methylene blue sensitized poly/vinyl alcohol)/acrylamide photopolymer material. Light from a low power He-Ne laser is focused into the material, and the evolution of the beam is monitored. The refractive index of the material is modulated in the region of high intensity due to photobleaching and photopolymerization effects occurring in the material.

Phase effects on synchronization by dynamical relaying in delay-coupled systems.

Synchronization in an array of mutually coupled systems with a finite time delay in coupling is studied using the Josephson junction as a model system. The sum of the transverse Lyapunov exponents is evaluated as a function of the parameters by linearizing the equation about the synchronization manifold. The dependence of synchronization on damping parameter, coupling constant,and time delay is studied numerically.

Phase synchronization in an array of driven Josephson junctions.

We consider an array of N Josephson junctions connected in parallel and explore the condition for chaotic synchronization. It is found that the outer junctions can be synchronized while they remain uncorrelated to the inner ones when an external biasing is applied. The stability of the solution is found out for the outer junctions in the synchronization manifold.

Variational approach to spatial optical solitons in bulk cubic-quintic media stabilized by self-induced multiphoton ionization.

Propagation of an optical high-power cylindrically symmetric beam in a material characterized by cubic-quintic nonlinearity is studied both analytically and numerically. In this case we have to consider the self-defocusing effect caused by the presence of free electrons produced due to plasma formation. The variational method is used to study the system analytically.

Soliton propagation in an erbium-doped fiber with and without a continuous wave background.

Considering ultrashort pulse propagation in a nonlinear resonant fiber governed by Hirota-Maxwell Bloch equations, the soliton interaction in an erbium-doped fiber system associated with higher-order dispersion, self-steepening, and self-induced transparency effects is studied for the case when the fiber is driven with and without a constant pumping source. Using auto-Bäcklund-transformation, one- and two-soliton solutions are generated. The significance of the results is discussed in detail.

Multisoliton solutions and integrability aspects of coupled higher-order nonlinear Schrodinger equations.

Using Painleve singularity structure analysis, we show that coupled higher-order nonlinear Schrodinger (CHNLS) equations admit the Painleve property. Using the results of the Painleve analysis, we succeed in Hirota bilinearizing the CHNLS equations for the integrable cases. Solving the Hirota bilinear equations, one soliton and two soliton solutions are explicitly obtained.