Interface localized modes and hybrid lattice solitons in waveguide arrays

We discuss the formation of guided modes localized at the interface separat- ing two different periodic photonic lattices. Employing the effective discrete model, we analyze linear and nonlinear interface modes and also predict the existence of stable interface solitons including the hybrid staggered/unstaggered lattice solitons with the tails belonging to spectral gaps of different types.Comment: 11 pages, 5 figures, submitted to Opt. Let

Two-color surface lattice solitons

We study the properties of surface solitons generated at the edge of a semi-infinite photonic lattice in nonlinear quadratic media, namely two-color surface lattice solitons. We analyze the impact of phase mismatch on existence and stability of surface modes, and find novel classes of two-color twisted surface solitons which are stable in a large domain of their existence.Comment: 4 pages, 5 figures, Submitted for publicatio

Interface solitons in two-dimensional photonic lattices

We analyze localization of light at the interface separating square and hexagonal photonic lattices, as recently realized experimentally in two-dimensional laser-written waveguide arrays in silica glass with self-focusing nonlinearity [A. Szameit {\em et al.}, Opt. Lett. {\bf 33}, 663 (2008)]. We reveal the conditions for the existence of {\em linear} and {\em nonlinear} surface states substantially influenced by the lattice topology, and study the effect of the different symmetries and couplings on the stability of two-dimensional interface solitons.Comment: 3 pages, 4 figures, submitted to Opt. Let

Observation of two-dimensional lattice interface solitons

We report on the experimental observation of two-dimensional solitons at the interface between square and hexagonal waveguide arrays. In addition to the different symmetry of the lattices, the influence of a varying refractive index modulation depth is investigated. Such variation strongly affects the properties of surface solitons residing at different sides of the interface.Comment: 14 pages, 5 figures, to appear in Optics Letter

Nonlinear localized modes at phase-slip defects in waveguide arrays

We study light localization at a phase-slip defect created by two semi-infinite mismatched identical arrays of coupled optical waveguides. We demonstrate that the nonlinear defect modes possess the specific properties of both nonlinear surface modes and discrete solitons. We analyze stability of the localized modes and their generation in both linear and nonlinear regimes.Comment: 3 pages, 6 figures, submitted to Opt. Let

Discrete surface solitons in semi-infinite binary waveguide arrays

We analyze discrete surface modes in semi-infinite binary waveguide arrays, which can support simultaneously two types of discrete solitons. We demonstrate that the analysis of linear surface states in such arrays provides important information about the existence of nonlinear surface modes and their properties. We find numerically the families of both discrete surface solitons and nonlinear Tamm (gap) states and study their stability properties.Comment: 3 pages, 4 figures, submitted to Opt. Let

Discrete surface solitons in two-dimensional anisotropic photonic lattices

We study nonlinear surface modes in two-dimensional {\em anisotropic} periodic photonic lattices and demonstrate that, in a sharp contrast to one-dimensional discrete surface solitons, the mode threshold power is lower at the surface, and two-dimensional discrete solitons can be generated easier near the lattice corners and edges. We analyze the crossover between effectively one- and two-dimensional regimes of the surface-mediated beam localization in the lattice.Comment: 3 pages, 4 figure

Discrete and surface solitons in photonic graphene nanoribbons

We analyze localization of light in honeycomb photonic lattices restricted in one dimension which can be regarded as an optical analog of (``armchair'' and ``zigzag'') graphene nanoribbons. We find the conditions for the existence of spatially localized states and discuss the effect of lattice topology on the properties of discrete solitons excited inside the lattice and at its edges. In particular, we discover a novel type of soliton bistability, the so-called geometry-induced bistability, in the lattices of a finite extent.Comment: three double-column pages, 5 figures, submitted for publicatio

Observation of localized modes at phase slips in two-dimensional photonic lattices

We study experimentally light localization at phase-slip waveguides and at the intersection of phase-slips in a two-dimensional (2D) square photonic lattice. Such system allows to observe a variety of effects, including the existence of spatially localized modes for low powers, the generation of strongly localized states in the form of discrete bulk and surface solitons, as well as a crossover between one-dimensional (1D) and 2D localization.Comment: 4 double-column pages, 6 figures, submitted for publicatio

Observation of surface solitons in chirped waveguide arrays

We report the observation of surface solitons in chirped semi-infinite waveguide arrays whose waveguides exhibit exponentially decreasing refractive indices. We show that the power threshold for surface wave formation decreases with an increase of the array chirp and that for sufficiently large chirp values linear surface modes are supported.Comment: 12 pages, 3 figures, to appear in Optics Letter