1,720,996 research outputs found
Bistable and tristable soliton switching in collinear arrays of linearly coupled waveguides
No full textThe soliton switching in an array of three, linearly coupled waveguides is investigated. Supported by a variational model, we show that a never nonlinear switching among stable localized states is possible in long couplers. The numerical integrations of the governing equations confirm this interesting phenomenon. These results can be extended to asymmetrical nonlinear directional couplers, where the asymmetry is in the nonlinear coefficients. The tristable operational mode is investigated too and the model furnishes valuable indications in order to realize it. The model also allows a physical insight into the more general problem of steering in arrays with a large number of waveguides. Finally, an exact, antisymmetric solution of the governing equations of the three-waveguide array is also investigated, because it shows dynamical properties that might be useful in all-optical switching
Tuning of surface plasmon polaritons beat length in graphene directional couplers
No full textWe investigate the tuning of the coupling of surface plasmon polaritons between two spatially separated graphene layers. We demonstrate that by slightly changing the chemical potential, a graphene coupler can switch from the bar to the cross state; as a consequence, the coupling coefficient in such structures can be easily controlled by means of an applied electrical signal
Analytical study of the nonlinear pulse dynamics in arrays of linearly coupled waveguides
No full textThe dynamics of nonlinear pulse propagation in arrays of linearly coupled optical waveguides is considered. For an array of three waveguides, a simplified model based on a variational method is able to predict the steady-state solutions and the strong coupling dynamics with a good degree of accuracy and to furnish a necessary condition for the existence of localized states, as confirmed by numerical solutions of the governing equations. The pulse-radiation interaction is also studied, revealing that additional, long-period oscillations overlap the linear coupling frequency. In the regime of initial conditions that lead to strong localization dynamics, we present a theoretical result that predicts to a good approximation the asymptotic localized state
Nonlinear dynamics of induced modulational instability in a self-focusing slab waveguide with normal dispersion
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