Rodrigo A. Vicencio

Observation of Surface Gap Solitons in Semi-Infinite Waveguide Arrays

We report on the observation of surface gap solitons found to exist at the interface between uniform and periodic dielectric media with defocusing nonlinearity. We demonstrate strong self-trapping at the edge of a LiNbO3 waveguide array and the formation of staggered surface solitons with propagation constant inside the first photonic band gap. We study the crossover between linear repulsion and nonlinear attraction at the surface, revealing the mechanism of nonlinearity-mediated stabilization of the surface gap modes.

Observation of Localized States in Lieb Photonic Lattices.

We present the first experimental demonstration of a new type of localized state in the continuum, namely, compacton-like linear states in flat-band lattices. To this end, we employ photonic Lieb lattices, which exhibit three tight-binding bands, with one being perfectly flat. Discrete predictions are confirmed by realistic continuous numerical simulations as well as by direct experiments. Our results could be of great importance for fundamental physics as well as for various applications where light needs to be conducted in a diffractionless and localized manner over long distances.

Discrete solitons and nonlinear surface modes in semi-infinite waveguide arrays.

We discuss the formation of self-trapped localized states near the edge of a semi-infinite array of nonlinear optical waveguides. We study a crossover from nonlinear surface states to discrete solitons by analyzing the families of odd and even modes centered at finite distances from the surface and reveal the physical mechanism of the nonlinearity-induced stabilization of surface modes.

Experimental observation of bulk and edge transport in photonic Lieb lattices

We analyze the transport of light in the bulk and at the edge of photonic Lieb lattices, whose unique feature is the existence of a flat band representing stationary states in the middle of the band structure that can form localized bulk states. We find that transport in bulk Lieb lattices is significantly affected by the particular excitation site within the unit cell, due to overlap with the flat band states. Additionally, we demonstrate the existence of new edge states in anisotropic Lieb lattices. These states arise due to a virtual defect at the lattice edges and are not described by the standard tight-binding model.

Controlled switching of discrete solitons in waveguide arrays.

We suggest an effective method for controlling nonlinear switching in arrays of weakly coupled optical waveguides. We demonstrate digitized switching of a narrow input beam for as many as 11 waveguides in the engineered waveguide arrays.

Fano Blockade by a Bose-Einstein Condensate in an Optical Lattice

We study the transport of atoms across a localized Bose-Einstein condensate in a one-dimensional optical lattice. For atoms scattering off the condensate, we predict total reflection as well as full transmission for certain parameter values on the basis of an exactly solvable model. The findings of analytical and numerical calculations are interpreted by a tunable Fano-like resonance and may lead to interesting applications for blocking and filtering atom beams.

Diffraction-free image transmission in kagome photonic lattices

We study the propagation of non-diffracting images in kagome photonic lattices. In a weak-coupling regime (discrete approach), the linear spectrum is composed by only three bands, including a completely degenerated and flat one. The states forming this special band are well localized in space and constitute building blocks for this lattice. By linearly combining these non-diffractive fundamental modes, different shapes can be composed and, therefore, a given image will propagate without distortion. As an example, we compare the linear propagation of a particular image for kagome and rectangular lattices. At the end, we test our concept by performing numerical simulations in a continuous kagome potential.

Trapping of discrete solitons by defects in nonlinear waveguide arrays

We study the trapping process of moving discrete solitons by linear and nonlinear impurities embedded in a one-dimensional nonlinear cubic array. We show that there exist specific values for the strength of the impurity and for the angle where a strong trapping is obtained. We introduce a criterion for studying the scattering dynamics of localized waves in nonlinear extended systems where the trapping of energy takes place.

Discrete surface solitons in two-dimensional anisotropic photonic lattices

We study nonlinear surface modes in two-dimensional 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.

All-optical switching and amplification of discrete vector solitons in nonlinear cubic birefringent waveguide arrays

We study all-optical switching based on the dynamic properties of discrete vector solitons in waveguide arrays. We employ the concept of polarization mode instability and demonstrate simultaneous switching and amplification of a weak signal by a strong pump of the opposite polarization.