Defect-free surface states in modulated photonic lattices

We predict that interfaces of periodically curved waveguide arrays can support a novel type of surface states which exist in a certain region of modulation parameters associated with the band flattening. Such linear surface states appear in truncated but otherwise perfect (defect-free) lattices as a direct consequence of the periodic modulation of the lattice potential. We show that the existence of these modes in different band gaps can be flexibly controlled by selecting the modulation profile, with no restrictions on Blochwave symmetries characteristic of Shockley states

Broadband diffraction management and self-collimation of white light in photonic lattices

We suggest a novel type of photonic structures where the strength of diffraction can be managed in a very broad frequency range. We introduce optimized arrays of curved waveguides where light beams experience wavelength-independent normal, anomalous, or zero diffraction. Our results suggest novel opportunities for efficient self-collimation, focusing, and reshaping of beams produced by white-light and super-continuum sources. We also show how to manipulate light patterns through multicolor Talbot effect, which is possible neither in free space nor in conventional photonic lattices.Comment: 5 pages, 4 figures; available at http://link.aps.org/abstract/PRE/v74/e06660

Dynamical trapping of light in modulated waveguide lattices

A discrete analogue of the dynamical (Kapitza) trapping effect, known for classical and quantum particles in rapidly oscillating potentials, is proposed for light waves in modulated graded-index waveguide lattices. As in the non-modulated waveguide lattice a graded-index potential can confine light at either normal or Bragg angle incidence, periodic modulation of the potential in the longitudinal direction enables to trap optical beams at both normal and Bragg incidence angles.Comment: to be published in Optics Letter

Surface multi-gap vector solitons

We analyze nonlinear collective effects near surfaces of semi-infinite periodic systems with multi-gap transmission spectra and introduce a novel concept of multi-gap surface solitons as mutually trapped surface states with the components associated with different spectral gaps. We find numerically discrete surface modes in semi-infinite binary waveguide arrays which can support simultaneously two types of discrete solitons, and analyze different multi-gap states including the soliton-induced waveguides with the guided modes from different gaps and composite vector solitons.Comment: 6 pages, 5 figure

Rectification of light refraction in curved waveguide arrays

An 'optical ratchet' for discretized light in photonic lattices, which enables to observe rectification of light refraction at any input beam conditions, is theoretically presented, and a possible experimental implementation based on periodically-curved zigzag waveguide arrays is proposed.Comment: 3 pages, 3 figure

Demonstration of all-optical beam steering in modulated photonic lattices

We demonstrate experimentally all-optical beam steering in modulated photonic lattices induced optically by three beam interference in a biased photorefractive crystal. We identify and characterize the key physical parameters governing the beam steering, and show that the spatial resolution can be enhanced by the additional effect of nonlinear beam self-localization.Comment: 3 pages, 3 figure

Shaping and switching of polychromatic light in arrays of periodically curved nonlinear waveguides

We overview our recent theoretical results on spatio-spectral control, diffraction management, and broadband all-optical switching of polychromatic light in periodically curved one and two dimensional arrays of coupled optical waveguides. In particular, we show that polychromatic light beams and patterns produced by white-light and supercontinuum sources can experience wavelength-independent normal, anomalous, or zero diffraction in specially designed structures. We also demonstrate that in the nonlinear regime, it is possible to achieve broadband all-optical switching of polychromatic light in a directional waveguide coupler with special bending of the waveguide axes. Our results suggest novel opportunities for creation of all-optical logical gates and switches which can operate in a very broad frequency region, e.g., covering the entire visible spectrum

Nonlinear diffusion and beam self-trapping in diffraction-managed waveguide arrays

We study nonlinear propagation of light in diffractionmanaged photonic lattices created by periodically-curved arrays of optical waveguides. We identify different regimes of the nonlinear propagation of light in such structures depending on the input power. We start from the regime of self-collimation at low powers and demonstrate that, as the beam power increases, nonlinearity destroys the beam self-imaging and leads to nonlinear diffusion. At higher powers, we observe a sharp transition to the self-trapping and the formation of discrete diffraction-managed solitons

Light Bullets in Nonlinear Periodically Curved Waveguide Arrays

We predict that stable mobile spatio-temporal solitons can exist in arrays of periodically curved optical waveguides. We find two-dimensional light bullets in one-dimensional arrays with harmonic waveguide bending and three-dimensional bullets in square lattices with helical waveguide bending using variational formalism. Stability of the light bullet solutions is confirmed by the direct numerical simulations which show that the light bullets can freely move across the curved arrays. This mobility property is a distinguishing characteristic compared to previously considered discrete light bullets which were trapped to a specific lattice site. These results suggest new possibilities for flexible spatio-temporal manipulation of optical pulses in photonic lattices.Comment: 7 pages, 4 figure

Polychromatic Optical Bloch Oscillations

Bloch oscillations (BOs) of polychromatic beams in circularly-curved optical waveguide arrays are smeared out owing to the dependence of the BO spatial period on wavelength. Here it is shown that restoring of the self-imaging property of the array and approximate BOs over relatively broad spectral ranges can be achieved by insertion of suitable lumped phase slips uniformly applied across the array.Comment: 3 pages, 4 figure