Showing papers by "Yuri S. Kivshar published in 2007"
TL;DR: It is revealed that stable higher-order optical solitons can exist in nonlocal nonlinear media in the various forms of soliton necklaces and soliton matrices.
Abstract: We introduce novel classes of higher-order spatial optical solitons in analogy with Laguerre-Gaussian and Hermite-Gaussian linear eigenmodes. We reveal that stable higher-order optical solitons can exist in nonlocal nonlinear media in the various forms of soliton necklaces and soliton matrices. Modulational instability can lead to nontrivial transformations between energetically close solitons with different symmetries through the intermediate states resembling generalized Hermite-Laguerre-Gaussian modes.
226 citations
TL;DR: In this paper, the authors studied the magnetic resonance of a split-ring resonator with a varactor diode at microwave frequencies and demonstrated different tuning regimes with and without an inductive coil in parallel with the varactor.
Abstract: We study both theoretically and experimentally the dynamic tunability of the magnetic resonance of a single nonlinear split-ring resonator with varactor diode at microwave frequencies. We demonstrate different tuning regimes with and without an inductive coil in parallel with the varactor. We show that the coil changes the sign of the nonlinearity and eliminates the memory effect caused by charge accumulation across the varactor. In addition, at higher powers the nonlinear response of the split-ring resonator becomes multivalued, paving a way for creating bistable tunable metamaterials.
109 citations
TL;DR: This work suggests and demonstrates a novel platform for the study of tunable nonlinear light propagation in two-dimensional discrete systems, based on photonic crystal fibers filled with high index nonlinear liquids, and experimentally demonstrates highly tunable beam diffraction and thermal self-defocusing.
Abstract: We suggest and demonstrate a novel platform for the study of tunable nonlinear light propagation in two-dimensional discrete systems, based on photonic crystal fibers filled with high index nonlinear liquids. Using the infiltrated cladding region of a photonic crystal fiber as a nonlinear waveguide array, we experimentally demonstrate highly tunable beam diffraction and thermal self-defocusing, and realize a compact all-optical power limiter based on a tunable nonlinear response.
86 citations
TL;DR: Wave propagation in mixed, 1D disordered stacks of alternating right- and left-handed layers is studied and it is revealed that the introduction of metamaterials substantially suppresses Anderson localization.
Abstract: We study wave propagation in mixed, 1D disordered stacks of alternating right- and left-handed layers and reveal that the introduction of metamaterials substantially suppresses Anderson localization. At long wavelengths, the localization length in mixed stacks is orders of magnitude larger than for normal structures, proportional to the sixth power of the wavelength, in contrast to the usual quadratic wavelength dependence of normal systems. Suppression of localization is also exemplified in long-wavelength resonances which largely disappear when left-handed materials are introduced.
86 citations
TL;DR: In this paper, the authors model the nonlinear behavior of spin-1 Bose-Einstein condensates (BECs) with repulsive spinindependent interactions and either ferromagnetic or antiferromagnetic (polar) spin-dependent interactions, loaded into a one-dimensional optical lattice potential.
Abstract: We model the nonlinear behavior of spin-1 Bose-Einstein condensates (BECs) with repulsive spin-independent interactions and either ferromagnetic or antiferromagnetic (polar) spin-dependent interactions, loaded into a one-dimensional optical lattice potential. We show that both types of BECs exhibit dynamical instabilities and may form spatially localized multicomponent structures. The localized states of the spinor matter waves take the form of vector gap solitons and self-trapped waves that exist only within gaps of the linear Bloch-wave band-gap spectrum. Of special interest are the nonlinear localized states that do not exhibit a common spatial density profile shared by all condensate components, and consequently cannot be described by the single mode approximation (SMA) frequently employed within the framework of the mean-field treatment. We show that the non-SMA states can exhibits Josephson-like internal oscillations and self-magnetization, i.e., intrinsic precession of the local spin. Finally, we demonstrate that nonstationary states of a spinor BEC in a lattice exhibit coherent undamped spin-mixing dynamics, and that their controlled conversion into a stationary state can be achieved by the application of an external magnetic field.
71 citations
TL;DR: The shape of the nonlocal response of a medium with thermal nonlinearity is retrieved and it is shown that despite its inherently infinite range it can be accurately characterized by a well-defined non local response function.
Abstract: We study experimentally and theoretically the nonlocal response of a medium with thermal nonlinearity and show that despite its inherently infinite range it can be accurately characterized by a well-defined nonlocal response function. We retrieve the shape of this function and analyze its transformation with the change of boundaries.
63 citations
TL;DR: From the experimental data, the ratio of d(32) and d(33) components of the second order susceptibility tensor and also the statistical properties of the random structure of the SBN crystal are determined.
Abstract: We study the second-harmonic (SH) parametric processes in unpoled crystals of Strontium Barium Niobate (SBN) with disordered structures of ferroelectric domains. Such crystals allow for the simultaneous phase matching of several second-order nonlinear processes. We analyze the polarization properties of these parametric processes using two types of generation schemes: quasi-collinear SH generation and transverse SH generation. From our experimental data we determine the ratio of d32 and d33 components of the second order susceptibility tensor and also the statistical properties of the random structure of the SBN crystal.
58 citations
TL;DR: In this paper, the transverse second-harmonic generation of counterpropagating pulses by a quasi-phase-matching in a medium with a random ferroelectric domain structure was investigated.
Abstract: The authors study experimentally the transverse second-harmonic generation of counterpropagating pulses by a quasi-phase-matching in a medium with a random ferroelectric domain structure. The authors show that this parametric process results in a direct realization of the cross correlation of two optical signals and, therefore, it can be employed for direct characterizations of ultrashort pulses including their temporal structure and pulse front tilt.
52 citations
TL;DR: In this paper, the propagation of linear magnetoinductive waves in arrays of split-ring resonators with different orientation and spacing was studied experimentally, and the effect of coupling of individual elements in magnetic composite metamaterials was characterized.
Abstract: We study experimentally the propagation of linear magnetoinductive waves in arrays of split-ring resonators with different orientation and spacing. We summarize our experimental results characterizing the effect of coupling of individual elements in magnetic composite metamaterials. We observe the band broadening due to the excitation of magnetoinductive waves which should impose some limitations on the effective medium approximation used to analyze metamaterials.
49 citations
TL;DR: Light self-trapping in triangular photonic lattices induced optically in nonlinear photorefractive crystals and the formation of two-dimensional discrete and gap spatial solitons originating from the first and second bands of the linear transmission spectrum are experimentally studied.
Abstract: We experimentally study light self-trapping in triangular photonic lattices induced optically in nonlinear photorefractive crystals. We observe the formation of two-dimensional discrete and gap spatial solitons originating from the first and second bands of the linear transmission spectrum.
48 citations
TL;DR: In this paper, the evolution of vortex solitons in optical media with a nonlocal nonlinear response was studied, and a modulation theory for the vortex parameters based on an averaged Lagrangian was employed to analyze the azimuthal evolution of the vortex width and diffractive radiation.
Abstract: We study the evolution of vortex solitons in optical media with a nonlocal nonlinear response. We employ a modulation theory for the vortex parameters based on an averaged Lagrangian, and analyze the azimuthal evolution of both the vortex width and diffractive radiation. We describe analytically the physical mechanism for vortex stabilization due to the long-range nonlocal nonlinear response, the effect observed earlier in numerical simulations only.
TL;DR: It is revealed that diffraction of different spectral components of polychromatic light can display completely different patterns in the same periodically modulated structure, e.g. one-dimensional, hexagonal, or rectangular.
Abstract: We study propagation of light beams in two-dimensional photonic lattices created by periodically curved waveguide arrays. We demonstrate that by designing the waveguide bending, one can control not only the strength and sign of the beam diffraction, but also to engineer the effective geometry and even dimensionality of the two-dimensional photonic lattice. We reveal that diffraction of different spectral components of polychromatic light can display completely different patterns in the same periodically modulated structure, e.g. one-dimensional, hexagonal, or rectangular. Our results suggest novel opportunities for efficient self-collimation, focusing, and reshaping of light beams in two-dimensional photonic structures.
TL;DR: A novel class of stable lattice solitons with a complex phase structure composed of many single-charge discrete vortices in a triangular photonic lattice are introduced and it is demonstrated that such nonlinear self-trapped states are linked to the resonant Bloch modes.
Abstract: We introduce a novel class of stable lattice solitons with a complex phase structure composed of many single-charge discrete vortices in a triangular photonic lattice. We demonstrate that such nonlinear self-trapped states are linked to the resonant Bloch modes, which bear a honeycomb pattern of phase dislocations.
TL;DR: In this article, the effect of anisotropy on the induced refractive-index patterns of periodic photonic lattices optically imprinted in photorefractive nonlinear media was explored.
Abstract: We study experimentally two-dimensional periodic photonic lattices optically imprinted in photorefractive nonlinear media, and explore the effect of anisotropy on the induced refractive-index patterns. The orientation anisotropy is demonstrated by comparing square and diamond lattices, while the polarization anisotropy is shown to distinguish ordinarily and extraordinarily polarized light. In particular, the extraordinarily polarized lattice induces much stronger refractive-index modulation for the same conditions. Finally, we exploit the photorefractive anisotropy to generate a quasi-one-dimensional refractive-index pattern for the observation of two-dimensional solitons and corroborate these experiments by numerical simulations.
TL;DR: Light propagation in arrays of weakly coupled nonlinear cavities driven by an inclined holding beam is studied and a crossover between resting and moving cavity solitons is analyzed, and novel features in the soliton collision are observed.
Abstract: We study light propagation in arrays of weakly coupled nonlinear cavities driven by an inclined holding beam. We show analytically that both discreteness and inclination of the driving field can dramatically change the conditions for modulational instability in discrete nonlinear systems. We find numerically the families of resting and moving dissipative solitons for an arbitrary inclination angle of the driving field, both in the discrete and a quasi-continuous limits. We analyze a crossover between resting and moving cavity solitons, and also observe novel features in the soliton collision.
TL;DR: The resonant transmission of light through a photonic-crystal waveguide side coupled to a Kerr nonlinear cavity is analyzed, and it is shown that the resonance quality factor in such structures scales inversely proportional to the group velocity of light at the resonant frequency and thus grows indefinitely in the slow-light regime.
Abstract: We analyze the resonant transmission of light through a photonic-crystal waveguide side coupled to a Kerr nonlinear cavity, and demonstrate how to design the structure geometry for achieving bistability and all-optical switching at ultralow powers in the slow-light regime. We show that the resonance quality factor in such structures scales inversely proportional to the group velocity of light at the resonant frequency and thus grows indefinitely in the slow-light regime. Accordingly, the power threshold required for all-optical switching in such structures scales as a square of the group velocity, rapidly vanishing in the slow-light regime.
TL;DR: The wave scattering by the junction defect is analyzed and nonzero reflection for any set of parameters is demonstrated and it is shown that if the junction is nonlinear, it is possible to achieve the maximum transmission for any frequency by tuning the intensity of the scattering wave.
Abstract: We study the properties of junctions created by the crossing of N identical branches of linear discrete networks. We reveal that for N>2 such a junction creates a topological defect and supports two types of spatially localized modes. We analyze the wave scattering by the junction defect and demonstrate nonzero reflection for any set of parameters. If the junction is nonlinear, it is possible to achieve the maximum transmission for any frequency by tuning the intensity of the scattering wave. In addition, near the maximum transmission the system shows the bistable behavior.
TL;DR: It is demonstrated the existence of two-dimensional surface light bullets localized in the lattice corners or the edges and the families of the spatiotemporal surface solitons and their properties such as bistability are studied.
Abstract: We analyze spatiotemporal light localization in truncated two-dimensional photonic lattices and demonstrate the existence of two-dimensional surface light bullets localized in the lattice corners or the edges. We study the families of the spatiotemporal surface solitons and their properties such as bistability and compare them with the modes located deep inside the photonic lattice.
TL;DR: A novel class of continuous-discrete spatiotemporal solitons, the so-called discrete surface light bullets, are demonstrated and it is shown that their properties are strongly affected by the presence of the surface.
Abstract: We analyze spatiotemporal light localization near the edge of a semi-infinite array of weakly coupled nonlinear optical waveguides and demonstrate the existence of a novel class of continuous-discrete spatiotemporal solitons, the so-called discrete surface light bullets. We show that their properties are strongly affected by the presence of the surface. To this end the crossover between surface and quasi-bulk bullets is studied by analyzing the families of solitons propagating at different distances from the edge of the waveguide array.
TL;DR: It is demonstrated that the parametric conversion of the Gaussian fundamental beam propagating along the axis of the annular structure leads to the axial emission of the second-harmonic field in the form of the radially polarized first-order Bessel beam.
Abstract: We analyze the second-harmonic generation in two-dimensional photonic structures with radially periodic domains created by poling of a nonlinear quadratic crystal. We demonstrate that the parametric conversion of the Gaussian fundamental beam propagating along the axis of the annular structure leads to the axial emission of the second-harmonic field in the form of the radially polarized first-order Bessel beam.
TL;DR: In this article, the authors acknowledge support from the Australian Research Council and thank Ekmel Ozbay for providing additional details of the experimental results published earlier by his group, which were used in their work.
Abstract: The authors acknowledge support from the Australian
Research Council and thank Ekmel Ozbay for providing additional
details of the experimental results published earlier
by his group.
TL;DR: In this article, the excitation of electromagnetic surface waves in a slab of a left-handed metamaterial separating a one-dimensional periodic photonic crystal and a homogeneous dielectric medium was studied.
Abstract: We study the excitation of electromagnetic surface waves in a slab of a left-handed metamaterial separating a one-dimensional periodic photonic crystal and a homogeneous dielectric medium, the so-called surface Tamm states. We show that such a layered structure can exhibit a giant lateral Goos-H\"anchen shift of the scattered beam accompanied by a splitting of the reflected and transmitted beams due to the resonant excitation of surface waves at the interfaces between the left-handed metamaterial and photonic crystal. The beam shift can be either positive or negative, depending on the type of the surface Tamm states excited by the incoming beam.
TL;DR: In this article, the authors review the recent developments in the field of photonic lattices emphasizing their unique properties for controlling linear and nonlinear propagation of light and draw some important links between optical lattices and photonic crystals pointing towards practical applications in optical communications and computing, beam shaping, and biosensing.
Abstract: We review the recent developments in the field of photonic lattices emphasizing their unique properties for controlling linear and nonlinear propagation of light. We draw some important links between optical lattices and photonic crystals pointing towards practical applications in optical communications and computing, beam shaping, and biosensing.
TL;DR: It is demonstrated that the lattice chirp can change dramatically the conditions for the mode localization near the surface, and the families of discrete surface solitons are found numerically in this case.
Abstract: We study surface modes at the edge of a semi-infinite chirped photonic lattice in the framework of an effective discrete nonlinear model. We demonstrate that the lattice chirp can change dramatically the conditions for the mode localization near the surface, and we find numerically the families of discrete surface solitons in this case. Such solitons do not require any minimum power to exist provided the chirp parameter exceeds some critical value. We also analyze how the chirp modifies the interaction of a soliton with the lattice edge.
TL;DR: An array of optical waveguides in a LiNbO3 crystal is used and the interplay between diffraction and nonlinearity to dynamically control the output spectrum of the supercontinuum radiation presents an efficient scheme for optically tunable spectral filtering of supercontinua.
Abstract: We present the first observation of spatiospectral control and localization of supercontinuum light through the nonlinear interaction of spectral components in extended periodic structures. We use an array of optical waveguides in a LiNbO3 crystal and employ the interplay between diffraction and nonlinearity to dynamically control the output spectrum of the supercontinuum radiation. This effect presents an efficient scheme for optically tunable spectral filtering of supercontinua.
TL;DR: Spatiotemporal dynamics of soliton-induced twooctave- broad supercontinuum generated by fs pulses in an array of coupled nonlinear waveguides are studied.
Abstract: We study spatiotemporal dynamics of soliton-induced two-octave-broad supercontinuum generated by fs pulses in an array of coupled nonlinear waveguides. We show that after fission of the input pulse into several fundamental solitons, red and blue-shifted nonsolitonic radiation, as well as solitons with lower intensity, spread away in transverse direction, while the most intense spikes self-trap into spatiotemporal discrete solitons.
TL;DR: It is demonstrated that, as the beam power increases, nonlinearity destroys the beam self-imaging and leads to nonlinear diffusion in diffraction-managed photonic lattices created by periodically-curved arrays of optical waveguides.
Abstract: We study nonlinear propagation of light in diffraction-managed photonic lattices created by periodically-curved arrays of optical waveguides. We identify different regimes of the nonlinear propagation of light in such structures depending on the input power. We start from the regime of self-collimation at low powers and demonstrate that, as the beam power increases, nonlinearity destroys the beam self-imaging and leads to nonlinear diffusion. At higher powers, we observe a sharp transition to the self-trapping and the formation of discrete diffraction-managed solitons.
TL;DR: In this article, the authors studied surface modes in semi-infinite chirped two-dimensional photonic lattices in the frame-work of an effective discrete nonlinear model and showed that the lattice chirp can change dramatically the conditions for the mode localization near the surface.
Abstract: We study surface modes in semi-infinite chirped two-dimensional photonic lattices in the frame- work of an effective discrete nonlinear model. We demonstrate that the lattice chirp can change dramatically the conditions for the mode localization near the surface, and we find numerically the families of surface modes, in linear lattices, and discrete surface solitons, in nonlinear lattices. We demonstrate that, in a sharp contrast to one-dimensional discrete surface solitons, in two-dimensional lattices the mode threshold power is lowered by the action of both the surface and lattice chirp. By manipulating with the lattice chirp, we can control the mode position and its localization.
TL;DR: In this paper, the propagation of rotating multi-soliton localized structures in optical media with spatially nonlocal nonlinearity is analyzed and it is shown that nonlocality stabilizes the azimuthal breakup of rotating dipole as well as multipole localized soliton modes.
Abstract: We analyze the propagation of rotating multi-soliton localized structures in optical media with spatially nonlocal nonlinearity. We demonstrate that nonlocality stabilizes the azimuthal breakup of rotating dipole as well as multipole localized soliton modes. We compare the results for two different models of nonlocal nonlinearity and suggest that the stabilization mechanism is a generic property of a spatial nonlocal nonlinear response independent of its particular functional form.
TL;DR: In this article, nonlinear surface modes in two-dimensional anisotropic periodic photonic lattices were studied and it was shown that, in contrast to one-dimensional discrete surface solitons, the mode threshold power is lower at the surface.