In the past few years, new developments in structured electromagnetic materials have given rise to negative refractive index materials which have both negative dielectric permittivity and negative magnetic permeability in some frequency ranges. The idea of a negative refractive index opens up new conceptual frontiers in photonics. One much-debated example is the concept of a perfect lens that e...

We study spatial optical solitons in a one-dimensional nonlinear photonic crystal created by an array of thin-film nonlinear waveguides, the so-called Dirac-comb nonlinear lattice. We analyze modulational instability of the extended Bloch-wave modes and also investigate the existence and stability of bright, dark, and "twisted" spatially localized modes in such periodic structures. Additionally...

In this paper, we present the theoretical studies of a refractive index map to implement a Gauss to a J(0)-Bessel-Gauss convertor. We theoretically demonstrate the viability of a device that could be fabricated on a Si/Si(1-y)O(y)/Si(1-x-y)Ge(x)C(y) platform or by photo-refractive media. The proposed device is 200 μm in length and 25 μm in width, and its refractive index varies in controllable ...

In this article we present the spectral and nonlinear optical properties of ZnO-TiO(2) nanocomposites prepared by colloidal chemical synthesis. Emission peaks of ZnO-TiO(2) nanocomposites change from 340 nm to 385 nm almost in proportion to changes in E(g). The nanocomposites show self-defocusing nonlinearity and good nonlinear absorption behaviour. The nonlinear refractive index and the nonlin...

We use a white-light continuum (WLC) Z-scan technique to measure the degenerate two-photon absorption spectrum and associated dispersion of the nonlinear refraction in ZnSe. The spectral components of the WLC source are separated by using a narrow band variable filter to minimize nondegenerate nonlinearities. We observe a change in sign of the ultrafast nonlinear refractive index around 0.7 of ...

Considering the coherent nonlinear dynamics between two weakly linked optical waveguide arrays, we find the first example of coexistence of Josephson oscillations with a novel self-trapping regime. This macroscopic bistability is explained by proving analytically the simultaneous existence of symmetric, antisymmetric, and asymmetric stationary solutions of the associated nonlinear Schrödinger e...

We developed a direct measurement method for comprehensive analyses of Kerr and plasma effects that cooperated or competed with molecular alignment-induced spatiotemporal modulation for intense aligning and weak probing pulses around zero time delay. The mixed influences were revealed by time-resolving the combined spatial focusing or defocusing dynamics under different molecular alignment dire...

In this paper we investigate focusing properties of graded index (GRIN) photonic crystal (PC) structures which are composed of different materials with different refractive indices. GRIN PC structure is constructed from air holes in dielectric background. The holes radii are varied in the normal direction to the propagation in such a way that a parabolic effective refractive index is produced. ...

We show that electrostriction contributes significantly to self-action effects in optical fibers, adding 19% to the nonlinear refractive index for fields that vary slowly compared with the ~1-ns time scale of the acoustic response. Electrostriction also modifies the tensor nature of the nonlinear-optical response. The electrostrictive nonlinearity is the origin of the observed difference betwee...

We calculate the nondegenerate bound electronic nonlinear refractive index n2 ( w1; w2) (i.e., an index change at frequency w1 due to the presence of a beam at frequency w2) in semiconductors. We calculate this nonlinearity and its disper~ sion using a Kramers-Kronig transformation on the calculated nondegenerate nonlinear absorption spectrum due to two-photon absorption, electronic Raman and o...