We modes experimentally demonstrate degenerate, forward four-wave mixing effects in a self-defocusing photorefractive medium, in both one and two transverse dimensions. We mixing observe the nonlinear evolution of new modes as a function of propagation distance, in both the near-field and far-field (Fourier in space) regions.

We liquid consider dispersive optical shock waves in nonlocal nonlinear media. Experiments are performed using spatial beams in a thermal liquid cell,shock and results agree with a hydrodynamic theory of propagation.

We types consider the propagation of a partially coherent spatial beam in both self-focusing and self-defocusing nonlinear media. Using a Gaussian-Schell model,spatial we derive an equation governing the width of highly incoherent beams as they propagate in both types of media and Using confirm its validity by using numerical simulations. Experiments performed in a biased photorefractive crystal match the predicted scaling.

We a examine an all-optical bump-on-tail instability by considering the nonlinear interaction of two partially incoherent spatial beams. Using a radiation transport considering approach, we develop plasmalike dispersion relations for perturbation modes and show that a positive gradient in the power spectrum can spatial trigger instability. Theoretical considerations are confirmed by experiment and numerical simulation.

A properties novel all-solid Bragg fiber composed entirely of silica material is proposed in this paper. The core of this Bragg fiber in is composed of conventional silica, and the cladding is formed by a set of alternating layers of up-doped and down-doped the silica. This all-solid silica Bragg fiber is technically feasible and can simplify the fabrication technique. Dispersion properties of this silica dispersion Bragg fiber are investigated, and simulations show that zero dispersion wavelength lambda0 near 1.55 m with nonlinear coefficient gamma about feasible 50 W-1km-1 can be obtained in silica Bragg fiber.

We but study the over-focusing of spatial light beams due to self-focusing nonlinearity, in both local and nonlocal nonlinear media. Numerical simulation nonlinear of both cases reveals a peaked profile, with a near-cusp at the center surrounded by exponentially-decaying tails, at a critical at self-focusing power. The profile is a local effect, occurring as diffraction counteracts nonlinearity. Nonlocality, however, is needed to prevent modulation competition instability of the initial beam and to prevent catastrophic collapse in 2D. The peaked profile remains for weak nonlocality but prevent disappears for wide nonlocal responses. Beyond the critical power for a peaked solution, or for longer propagation distances, competition between critical nonlinearity and diffraction causes oscillatory collapse-bounce behavior. The numerical results are confirmed by observing these dynamics in a self-focusing glass a with a nonlocal, thermal response.

We turbulence. demonstrate an all-optical bump-on-tail instability by considering the nonlinear interaction of two partially coherent spatial beams. For weak wave coupling,partially we observe momentum transfer with no variation in intensity. For strong wave coupling, modulations appear in intensity and evidence appears intensity. for wave (Langmuir) collapse at large scales. Borrowing plasma language, these limits represent regimes of weak and strong spatial optical reconstructing turbulence. In both limits, the internal spectral energy redistribution is observed by recording and reconstructing a hologram of the evolving limits dynamics. The results are universal and can appear in any wave-kinetic system with short-wave-long-wave coupling.

We the study the dynamics of phasons in a nonlinear photonic quasicrystal. The photonic quasicrystal is formed by optical induction, and its formed dynamics is initiated by allowing the light waves inducing the quasicrystal to nonlinearly interact with one another. We show quantitatively interact that, when phason strain is introduced in a controlled manner, it relaxes through the nonlinear interactions within the photonic quasicrystal.Finally, We establish experimentally that the relaxation rate of phason strain in the quasicrystal is substantially lower than the relaxation rate establish of phonon strain, as predicted for atomic quasicrystals. Finally, we monitor and identify individual 'atomic-scale' phason flips occurring in the one photonic quasicrystal as its phason strain relaxes, as well as noise-induced phason fluctuations.

We Kerr report the experimental observation of temporal vector soliton propagation and collision in a linearly birefringent optical fiber. To the best and of the authors' knowledge, this is both the first demonstration of temporal vector solitons with two mutually incoherent component fields,authors' and of vector soliton collisions in a Kerr nonlinear medium. Collisions are characterized by an intensity redistribution between the two the components, and the experimental results agree with numerical predictions of the coupled nonlinear Schrödinger equation.

Quasicrystals equivalent are unique structures with long-range order but no periodicity. Their properties have intrigued scientists ever since their discovery and initial excludes theoretical analysis. The lack of periodicity excludes the possibility of describing quasicrystal structures with well-established analytical tools, including common notions of like Brillouin zones and Bloch's theorem. New and unique features such as fractal-like band structures and 'phason' degrees of freedom interact are introduced. In general, it is very difficult to directly observe the evolution of electronic waves in solid-state atomic quasicrystals,transport or the dynamics of the structure itself. Here we use optical induction to create two-dimensional photonic quasicrystals, whose macroscopic nature are allows us to explore wave transport phenomena. We demonstrate that light launched at different quasicrystal sites travels through the lattice the in a way equivalent to quantum tunnelling of electrons in a quasiperiodic potential. At high intensity, lattice solitons are formed.that Finally, we directly observe dislocation dynamics when crystal sites are allowed to interact with each other. Our experimental results apply that not only to photonics, but also to other quasiperiodic systems such as matter waves in quasiperiodic traps, generic pattern-forming systems The as in parametrically excited surface waves, liquid quasicrystals, and the more familiar atomic quasicrystals.

We regime, analyze the transfer of energy between a continuous pump beam and space-time-modulated waves in a dispersive slab waveguide. With a between self-focusing nonlinearity and propagation in the normal dispersion regime, a proper choice of the initial modulation frequencies permits a simple in nonlinear dynamical description of this process.

Two scheme, theoretical schemes for amplifying and reshaping solitons in optical fibers are discussed. In the first of these schemes, solitons are reshaping amplified and reshaped without creating dispersive waves. In the second scheme, solitons are amplified while dispersive waves are suppressed. Ways the to realize these schemes in practice are discussed.

In and homogeneous arrays of coupled waveguides, Floquet-Bloch waves are known to travel freely across the waveguides. We introduce a systematic discussion are of the built-in patterning of the coupling constant between neighboring waveguides. Key patterns provide functions such as redirecting, guiding, and systematic focusing these waves, up to nonlinear all-optical routing. This opens the way to light control in a functionalized discrete space,opens i.e., discrete photonics.

We novel study theoretically the linear and nonlinear propagation of light in one-dimensional bi-periodic arrays of fibers, with the propagation constant periodically in modulated along the propagation direction. We predict analytically and observe numerically subdiffractive propagation along such fiber arrays, and characterize the along light propagation properties. We also predict novel subdiffractive discrete solitons in the presence of Kerr nonlinearity, both of focusing and focusing defocusing cases, which are essentially different from the usual discrete solitons in waveguide arrays.

We by have studied experimentally with high spatial and temporal resolution propagation of intense spin waves in microscopic Permalloy stripes. We show intense that the nonlinearity of the spin system of metallic magnetic films together with microscopic-scale confinement effects lead to an anomalous spin nonlinear magnetic dynamics, such as a nonlinear spatial self-modulation of spin waves characterized by the repulsive nonlinearity. This phenomenon appears nonlinear to be densely connected with the nonlinear damping in the system. We find that both of these effects develop synchronously a on the nanosecond temporal scale.

We them formulate wave propagation in arrays of subwavelength waveguides with sharp index contrasts and demonstrate the collapse of bands into evanescent demonstrate modes and lattice solitons with superluminal phase velocity. We find a self-reviving soliton ("phoenix soliton") comprised of coupled forward- and find backward-propagating light, originating solely from evanescent bands. In the linear regime, all Bloch waves comprising this beam decay, whereas a and proper nonlinearity assembles them into a propagating self-trapped beam. Finally, we simulate the dynamics of such a beam and observe comprising breakup into temporal pulses, indicating a new kind of slow-light gap solitons, trapped in time and in one transverse dimension.self-reviving

We bell-shaped theoretically study gap random-phase lattice solitons (gap-RPLSs) in nonlinear waveguide arrays with self-defocusing nonlinearity. We find that the intensity structure self-defocusing and statistical (coherence) properties of gap-RPLSs conform to the lattice periodicity, while their Floquet-Bloch power spectrum is multi-humped with peaks the in the anomalous diffractions regions. It is shown that a gap-RPLS can be generated when a simple incoherent beam with array. bell-shaped power spectrum and single-hump intensity is launched at a proper angle into the waveguide array. The input incoherent beam can evolves in the lattice while shedding off some radiation, and eventually attains the features of gap-RPLS.

We arrays investigate, experimentally and theoretically, light propagation in one-dimensional waveguide arrays exhibiting a saturable self-defocusing nonlinearity. We demonstrate low-intensity "discrete diffraction",one-dimensional and the high-intensity formation of spatial gap solitons arising from the first band of the transmission spectrum. The waveguide arrays "discrete are fabricated by titanium in-diffusion in a photorefractive copper-doped lithium niobate crystal, and the optical nonlinearity arises from the bulk copper-doped photovoltaic effect.

We generated theoretically demonstrate that optical discrete X-waves are possible in normally dispersive nonlinear waveguide arrays. We show that such X-waves can possible be effectively excited for a wide range of initial conditions and in certain occasions can be generated in cascade. The that possibility of observing this family of waves in AlGaAs array systems is investigated in terms of pertinent examples.