arXiv subjects

Yuri Kivshar

Publications and source records attributed to Yuri Kivshar.

124 records · Page 7Linked to original sources

arXiv2012

Tunable hybrid surface waves supported by a graphene layer

We study surface waves localized near a surface of a semi-infinite dielectric medium covered by a layer of graphene in the presence of a strong external magnetic field. We demonstrate that both TE-TM hybrid surface plasmons can propagate along the graphene surface. We analyze the effect of the Hall conductivity on the disper- sion of hybrid surface waves and suggest a possibility to tune the plasmon dispersion by the magnetic field.

physics.optics↗

arXiv2012

Nanoradar based on nonlinear dimer nanoantenna

We introduce the concept of a nanoradar based on the operation of a nonlinear plasmonic nanoantenna. The nanoradar action originates from modulational instability occurred in a dimer nanoantenna consisting of two subwavelength nonlinear nanoparticles. Modulation instability causes a dynamical energy exchange between the nanoantenna eigenmodes resulting in periodic scanning of the nanoantenna scattering pattern. Such nanoradar demonstrates a wide scanning sector, low operation threshold, and ultrafast time response being potentially useful for many applications in nanophotonics circuitry.

physics.optics↗

arXiv2011

Spontaneous emission enhancement in metal-dielectric metamaterials

We study the spontaneous emission of a dipole emitter imbedded into a layered metal-dielectric metamaterial. We demonstrate ultra-high values of the Purcell factor in such structures due to a high density of states with hyperbolic isofrequency surfaces. We reveal that the traditional effective-medium approach greatly underestimates the value of the Purcell factor due to the presence of an effective nonlocality, and we present an analytical model which agrees well with numerical calculations.

physics.optics↗

arXiv2010

Complete spectral gap in coupled dielectric waveguides embedded into metal

We study a plasmonic coupler involving backward (TM_01) and forward (HE_11) modes of dielectric waveguides embedded into infinite metal. The simultaneously achievable contradirectional energy flows and codirectional wavevectors in different channels lead to a spectral gap, despite the absence of periodic structures along the waveguide. We demonstrate that a complete spectral gap can be achieved in a symmetric structure composed of four coupled waveguides.

physics.optics↗

arXiv2009

Incoherent interaction of nematicons in bias-free liquid-crystal cells

We study experimentally the propagation dynamics and interaction of a pair of mutually incoherent nematicons: spatial optical solitons in nematic liquid crystals. In contrast to earlier studies, we consider a bias-free liquid-crystal cell and compare the soliton interaction in copropagating and counterpropagating geometries. We analyze the dependence of nematicon interaction on input power and observe a direct manifestation of a long-range nonlocal nonlinearity. Attraction of counterpropagating solitons requires higher powers and longer relaxation times than that of copropagating nematicons due to losses-induced power asymmetry of counterpropagating nematicons.

nlin.PS↗

arXiv2009

Structural tunability in metamaterials

We propose a novel approach for efficient tuning of the transmission characteristics of metamaterials through a continuous adjustment of the lattice structure, and confirm it experimentally in the microwave range. The concept is rather general and applicable to various metamaterials as long as the effective medium description is valid. The demonstrated continuous tuning of metamaterial response is highly desirable for a number of emerging applications of metamaterials including sensors, filters, switches, realizable in a wide frequency range.

physics.optics↗

arXiv2008

Experimental studies of the internal Goos-Hanchen shift for self-collimated beams in two-dimensional microwave photonic crystals

We study experimentally the Goos-Hanchen effect observed at the reflection of a self-collimated beam from the surface of a two-dimensional photonic crystal and describe a method for controlling the beam reflection through surface engineering. The microwave photonic crystal, fabricated from alumina rods, allows control of the output position of a reflected beam undergoing an internal Goos-Hanchen shift by changing the rod diameter at the reflection surface. The experimental data is in good agreement with the results of the finite-difference time-domain numerical calculations.

physics.optics↗

arXiv2005

Bandgap properties of two-dimensional low-index photonic crystals

We study the bandgap properties of two-dimensional photonic crystals created by a lattice of rods or holes conformed in a symmetric or asymmetric triangular structure. Using the plane-wave analysis, we calculate a minimum value of the refractive index contrast for opening both partial and full two-dimensional spectral gaps for both TM and TE polarized waves. We also analyze the effect of ellipticity of rods and holes and their orientation on the threshold value and the relative size of the bandgap.

physics.optics↗

arXiv2004

Generation of spin-wave dark solitons with phase engineering

We generate experimentally spin-wave envelope dark solitons from rectangular high-frequency dark input pulses with externally introduced phase shifts in yttrium-iron garnet magnetic fims. We observe the generation of both odd and even numbers of magnetic dark solitons when the external phase shift varies. The experimental results are in a good qualitative agreement with the theory of the dark-soliton generation in magnetic films developed earlier [Phys. Rev. Lett. 82, 2583 (1999)].

nlin.PS↗

arXiv2004

Stable Vortex Solitons in Nonlocal Self-Focusing Nonlinear Media

We reveal that spatially localized vortex solitons become stable in self-focusing nonlinear media when the vortex symmetry-breaking azimuthal instability is eliminated by a nonlocal nonlinear response. We study the main properties of different types of vortex beams and discuss the physical mechanism of the vortex stabilization in spatially nonlocal nonlinear media.

nlin.PS↗

arXiv2003

Second-harmonic generation in vortex-induced waveguides

We study the second-harmonic generation and localization of light in a reconfigurable waveguide induced by an optical vortex soliton in a defocusing Kerr medium. We show that the vortex-induced waveguide greatly improves conversion efficiency from the fundamental to the second harmonic field.

nlin.PS↗

arXiv2003

Partially incoherent optical vortices in self-focusing nonlinear media

We observe stable propagation of spatially localized single- and double-charge optical vortices in a self-focusing nonlinear medium. The vortices are created by self-trapping of partially incoherent light carrying a phase dislocation, and they are stabilized when the spatial incoherence of light exceeds a certain threshold. We confirm the vortex stabilization effect by numerical simulations and also show that the similar mechanism of stabilization applies to higher-order vortices.

nlin.PS↗

arXiv2003

Nonlinear optical beams carrying phase dislocations

We describe different types of self-trapped optical beams carrying phase dislocations, including vortex solitons and ring-like soliton clusters. We demonstrate numerically how to create such nonlinear singular beams by the interaction of several fundamental optical solitons. Mutual trapping of several solitons can be regarded as a synthesis of `soliton molecules', and it corresponds to a transfer of an initial orbital angular momentum of a system of solitons to a spin momentum of an optical vortex.

nlin.PS↗

arXiv2003

Soliton transverse instabilities in anisotropic nonlocal self-focusing media

We study, both theoretically and experimentally, the transverse modulational instability of spatial stripe solitons in anisotropic nonlocal photorefractive media. We demonstrate that the instability scenarios depend strongly on the stripe orientation, but the anisotropy-induced features are largely suppressed for spatial solitons created by self-trapping of partially incoherent light.

nlin.PS↗

arXiv2003

Spatial Solitons in Optically-Induced Gratings

We study experimentally nonlinear localization effects in optically-induced gratings created by interfering plane waves in a photorefractive crystal. We demonstrate the generation of spatial bright solitons similar to those observed in arrays of coupled optical waveguides. We also create pairs of out-of-phase solitons which resemble ``twisted'' localized states in nonlinear lattices.

nlin.PS↗

arXiv1998

Optical Gap Solitons in Nonresonant Quadratic Media

We demonstrate an important role of the process of optical rectification in the theory of nonlinear wave propagation in quadratically nonlinear [or $χ^{(2)}$ ] periodic optical media. We derive a novel physical model for gap solitons in $χ^{(2)}$ nonlinear Bragg gratings.

patt-sol↗