Nikos Efremidis

Discrete solitons in nonlinear zigzag optical waveguide arrays with tailored diffraction properties

We show that the discrete diffraction properties of a nonlinear optical zigzag waveguide array can be significantly modified, by exploiting the topological arrangement of the lattice itself. This introduces extended interactions (beyond nearest-neighbors), which, in turn, affect the lattice dispersion relation within the Brillouin zone. As a result, we demonstrate that new families of discrete soliton solutions are possible which are stable over a wide range of parameters. Our method opens new opportunities for diffraction management that can be employed to generate low power spatial discrete optical solitons.

Complex-cubic Ginzburg–Landau equation-based model for erbium-doped fiber-amplifier-supported nonreturn-to-zero communications

The propagation of nonreturn-to-zero pulses, composed by a superposition of two exact shock-wave solutions of a complex-cubic Ginzburg–Landau equation linearly coupled to a linear nondispersive equation, is studied in detail. The model describes the distributed (average) propagation in a dual-core erbium-doped fiber-amplifier-supported optical-fiber system where stabilization is achieved by means of short segments of an extra lossy core that is parallel and coupled to the main one. The linear-stability analysis of the two asymptotic states of the shock wave in combination with direct numerical simulations provide necessary conditions for optimal propagation of the nonreturn-to-zero pulse. The enhancement of the propagation distance by at least an order of magnitude, under a suitable choice of the parameters, establishes the beneficial role of the passive channel.

Surface Lattice Solitons: Analytical Solutions of a Kronig-Penney Model

A novel phase-space method is employed for the construction of analytical stationary solitary waves located and robustly propagating at the interface between a periodic nonlinear Kronig-Penney lattice and a linear or nonlinear homogeneous medium.

Surface lattice solitons: analytical solutions

A novel phase-space method is employed for the construction of analytical stationary solitary waves located at the interface between a periodic nonlinear lattice of the Kronig-Penney type and a linear (or nonlinear) homogeneous medium. The method provides physical insight and understanding of the shape of the solitary wave profile and results to generic classes of localized solutions having a zero background or nonzero semi-infinite background. For all cases, the method provides conditions for the values of the propagation constant of the stationary solutions and the linear refractive index in each part in order to assure existence of solutions with specific profile characteristics. The evolution of the analytical solutions under propagation is investigated for cases of realistic configurations and interesting features are presented while their remarkable robustness is shown to facilitate their experimental observation.

H - waves in nonlinear AlGaAs waveguide arrays

We theoretically demonstrate that optical discrete H-waves are possible in normally dispersive waveguide arrays. Methods to excite this family of waves in AlGaAs systems are presented.

Discrete solitons in optically-induced photonic lattices

This study presents the first experimental observation of 2D optical discrete solitons in nonlinear photonic lattices. This work shows 2D discrete solitons that belong to both classes: the inphase and the staggered solitons, residing at the base and the edge of the first Brillouin zone, respectively.