Dark Solitons in Discrete Lattices: Saturable versus Cubic Nonlinearities

In the present work, we study dark solitons in dynamical lattices with the saturable nonlinearity and compare them with those in lattices with the cubic nonlinearity. This comparison has become especially relevant in light of recent experimental developments in the former context. The stability properties of the fundamental waves, for both on-site and inter-site modes, are examined analytically and corroborated by numerical results. Furthermore, their dynamical evolution when they are found to be unstable is obtained through appropriately crafted numerical experiments.Comment: 15 pages, 5 figure

Dark solitons in discrete lattices: Saturable versus cubic nonlinearities

In the present work, we study dark solitons in dynamical lattices with the saturable nonlinearity and compare them to those in lattices with the cubic nonlinearity. This comparison has become especially relevant in light of recent experimental developments in the former context. The stability properties of the fundamental waves, for both onsite and intersite modes, are examined analytically and corroborated by numerical results. Our findings indicate that for both models onsite solutions are stable for sufficiently small values of the coupling between adjacent nodes, while intersite solutions are always unstable. The nature of the instability (which is oscillatory for onsite solutions at large coupling and exponential for inter-site solutions) is probed via the dynamical evolution of unstable solitary waves through appropriately crafted numerical experiments; typically, these computations result in dynamic motion of the originally stationary solitary waves. Another key finding, consistent with recent experimental results, is that the instability growth rate for the saturable nonlinearity is found to be smaller than that of the cubic case

Slow light in insulator-metal-insulator plasmonic waveguides

We study numerically the slow-light capability of insulator-metal-insulator (IMI) plasmonic waveguides. Metalinduced losses are included in the calculation of the dispersion relations, and their effect on the slow-light properties of the waveguide is investigated. In addition to reducing the propagation lengths of surface plasmon polaritons, losses are found to limit the achievable slowdown factors and the practical potential of the device. To alleviate the problem, we consider active materials. Using realistic parameters, we find that a spectral region is then formed where a slow-light pulsed signal can achieve infinite propagation lengths or be amplified. The optical buffering capabilities of the IMI waveguide with losses are analyzed, and we conclude that while losses limit the buffering capabilities of the passive device, the use of active materials may combat the problem effectively from an application point of view. © 2011 Optical Society of America