116 research outputs found
Soliton excitation in waveguide arrays with an effective intermediate dimensionality
We reveal and observe experimentally significant modifications undertaken by
discrete solitons in waveguide lattices upon the continuous transformation of
the lattice structure from one-dimensional to two-dimensional. Light evolution
and soliton excitation in arrays with a gradually increasing number of rows are
investigated, yielding solitons with an effective reduced dimensionality
residing at the edge and in the bulk of the lattice.Comment: 14 pages, 5 figures, to appear in Physical Review Letter
Nonlinearity-induced broadening of resonances in dynamically modulated couplers
We report the observation of nonlinearity-induced broadening of resonances in
dynamically modulated directional couplers. When the refractive index of the
guiding channels in the coupler is harmonically modulated along the propagation
direction and out-of-phase in two channels, coupling can be completely
inhibited at resonant modulation frequencies. We observe that nonlinearity
broadens such resonances and that localization can be achieved even in detuned
systems at power levels well below those required in unmodulated couplers.Comment: 14 pages, 4 figures, to appear in Optics Letter
Observation of two-dimensional surface solitons in anisotropic waveguide arrays
We report on the experimental observation of two-dimensional surface waves
localized at the edge or in the corner of femtosecond laser-written waveguide
arrays in fused silica. Increasing the power of the input beam allows one to
observe a clear transition from a linear diffraction pattern to localized
nonlinear surface states, which can exist at the interface only above a certain
power threshold.Comment: 13 pages, 4 figure
Two-dimensional solitons at interfaces between binary superlattices and homogeneous lattices
We report on the experimental observation of two-dimensional surface solitons
residing at the interface between a homogeneous square lattice and a
superlattice that consists of alternating "deep" and "shallow" waveguides. By
exciting single waveguides in the first row of the superlattice, we show that
solitons centered on deep sites require much lower powers than their respective
counterparts centered on shallow sites. Despite the fact that the average
refractive index of the superlattice waveguides is equal to the refractive
index of the homogeneous lattice, the interface results in clearly asymmetric
output patterns.Comment: 16 pages, 5 figures, to appear in Physical Review
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
Optics in Curved Space
We experimentally study the impact of intrinsic and extrinsic curvature of space on the evolution of light. We show that the topology of a surface matters for radii of curvature comparable with the wavelength, whereas for macroscopically curved surfaces only intrinsic curvature is relevant. On a surface with constant positive Gaussian curvature we observe periodic refocusing, self-imaging, and diffractionless propagation. In contrast, light spreads exponentially on surfaces with constant negative Gaussian curvature. For the first time we realized two beam interference in negatively curved space
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
Diffraction-managed solitons and nonlinear beam diffusion in modulated waveguide arrays
We present the first experimental observation of nonlinear beam diffusion and formation of diffraction-managed solitons in periodically-curved arrays of coupled optical waveguides created using femtosecond laser writing in silica glass, and titanium indiffusion in LiNbO3 crystals
Wave localization at the boundary of disordered photonic lattices
We report on the experimental observation of reduced light energy transport
and disorder-induced localization close to a boundary of a truncated
one-dimensional (1D) disordered photonic lattice. Our observations uncover that
near the boundary a higher level of disorder is required to obtain similar
localization than in the bulk.Comment: 13 pages, 5 figures, to appear in Optics Letter
Surface solitons at interfaces of arrays with spatially-modulated nonlinearity
We address the properties of two-dimensional surface solitons supported by
the interface of a waveguide array whose nonlinearity is periodically
modulated. When the nonlinearity strength reaches its minima at the points
where the linear refractive index attains its maxima, we found that nonlinear
surface waves exist and can be made stable only within a limited band of input
energy flows, and for lattice depths exceeding a lower threshold.Comment: 13 pages, 3 figures, to appear in Optics Letter
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