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Andrea Fratalocchi

Publications and source records attributed to Andrea Fratalocchi.

8 recordsLinked to original sources
PubMed2006

Dispersion spectroscopy of photonic lattices.

We theoretically demonstrate how to acquire the full bandgap spectrum of a photonic lattice of arbitrary profile. Focusing on the 1D case in the presence of a linear refractive index acceleration and employing a multiscale analysis, we show that each photonic band can be directly mapped by the light evolution in the lattice, whereas the size of each gap corresponds to the tunneling rate. We verify the analytical results with numerical simulations and discuss experimental realizations of this technique for dispersive spectroscopy.

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PubMed2006

Governing soliton splitting in one-dimensional lattices.

We investigate discrete light dynamics in the presence of a longitudinal defect of arbitrary extension, amplitude and position in a nonlinear waveguide array. We model and discuss the physics of the soliton-defect interaction, showing how to gain complete control over the system outcome for soliton-based data processing. We propose all-optical management in dye-doped liquid crystals.

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PubMed2006

Optically induced zener tunneling in one-dimensional lattices.

We investigate Landau-Zener tunneling in one-dimensional liquid crystalline waveguide arrays by all-optical impression of acceleration with an additional beam. We derive the Zener model from the governing equations and demonstrate a novel approach to Floquet-Bloch band tunneling.

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PubMed2005

Discrete light localization in one-dimensional nonlinear lattices with arbitrary nonlocality.

We model discrete spatial solitons in a periodic nonlinear medium encompassing any degree of transverse nonlocality. Making a convenient reference to a widely used material--nematic liquid crystals--we derive a form of the discrete nonlinear Schrödinger equation and find a family of discrete solitons. Such self-localized solutions in optical lattices can exist with an arbitrary degree of imprinted chirp and have breathing character. We verify numerically that both local and nonlocal discrete light propagation and solitons can be observed in liquid crystalline arrays.

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PubMed2005

Electro-optic routing in a nematic liquid-crystal waveguide.

We propose a versatile guided-wave geometry encompassing electro-optic control for signal routing. A zero-gap directional coupler in liquid crystal can switch between two output states in the guide plane, permitting signal rerouting with modulation voltages as small as 70 mV. In the absence of an applied bias, no guiding--hence no modal output--is provided by the structure.

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PubMed2005

Optical multiband vector breathers in tunable waveguide arrays.

We investigate multiband optical breathers in a voltage-adjustable array of coupled waveguides in nematic liquid crystals. Symmetric breathers resulting from vector composition of modes from two bands are observed over large propagation distances and are described in terms of the Floquet-Bloch theory.

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PubMed2004

Discrete propagation and spatial solitons in nematic liquid crystals.

We investigate, for the first time to our knowledge, the discrete propagation of near-infrared light in a voltage-controlled array of channel waveguides in undoped nematic liquid crystals under planar anchoring conditions. This novel geometry enables us to drive the system from one-dimensional bulk diffraction to discrete propagation and, for larger excitations, to discrete spatial solitons, or nematicons. The observed phenomena are adequately described by a scalar model that encompasses the voltage-dependent reorientational response of the material.

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