We dispersive experimentally study dispersive shock waves in nonlinear waveguide arrays. In contrast with gap solitons, the nonlinearity here pushes the propagation observe constant further into the transmission bands, facilitating Bloch mode coupling and energy transport. We directly observe this coupling, both within energy and between bands, by recording intensity in position space and power spectra in momentum space.

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

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

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

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

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

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

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

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

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

Image based retrieval based on degenerate four-wave mixing with a new nonlinear mechanism is demonstrated. An avalanche nonlinearity associated with induced excited-state conjugation absorption is exploited to furnish phase conjugation with threshold behavior and potential motion sensitivity. Population pulsations are reported at high to intensities.

We self-defocusing find strong self-defocusing in bacteriorhodopsin films in the near IR with powers in the tens of milliwatts. The defocused beam demonstrate acquires a ring pattern because of spatial self-phase modulation. We also demonstrate efficient four-wave mixing with phase-conjugate reflectivities of 26%.self-phase We discuss the origin of this high nonlinearity.

We an give an argument that the TE( ) guided wave of a thin-film slab waveguide with a nonlinear self-defocusing bounding medium is spite always stable in spite of the fact that its nonlinear dispersion curve has a negative slope.

Far-infrared been techniques have been developed that make possible the first observation to our knowledge of resonant four-wave mixing of submillimeter-wave radiation field, in n-type InSb maintained at 2 K. The dependences of the emission strength on dc magnetic field, circular polarization, and strength carrier concentration demonstrate that the resonant nonlinear process involves the collective excitations of the electron gas.

We experiment describe an experiment that generates squeezed states by means of forward four-wave mixing in sodium vapor with a single optical nonlinear beam. The single-beam arrangement maximizes the pump-probe spatial overlap in the nonlinear medium. Self-focusing (or self-defocusing) is found to be spatial the major limiting factor in achieving optimal squeezing.

The nonlinearity photorefractive nonlinearity associated with the Dember space-charge field between electrons and holes produced by two-photon absorption is unambiguously isolated and using studied in undoped CdTe by using a nondegenerate, forward-probing, polarization-sensitive, transient-grating technique with a temporal resolution of <5 ps.

We consider consider the validity of the reciprocity theorem as applied to steady-state photorefractive wave mixing. constants of integration in four-wave mixing in are physically interpreted as results of reciprocity.

We two-wave have measured the nearly degenerate two-wave mixing in GdAlO(3):Cr(3+) crystals. In contrast to that in other chromium-doped materials, the signal r in this sample arises from a mixed phase absorption grating where the absorption contribution is intensity dependent. The real (n(2)')excited-state and the imaginary (n(2)'') parts of the nonlinear index of refraction, the saturation intensity, and the excited-state lifetime are determined.= The ratio r = n(2)''/n(2)' changes linearly with the intensity. Owing to saturation, the grating presents anharmonicities that give rise that to self-diffracted beams (forward four-wave mixing). For comparison, results are also presented for ruby and alexandrite.

The two-wave theory for two-wave mixing in photorefractive InP:Fe under a dc electric field with both electron-hole intrinsic resonance and a moving predicted. grating is developed. An extended resonance condition is predicted. The phenomenon is proved experimentally, even though a quantitative discrepancy remains resonance between theory and experiments.