arXiv subjects

Yuri S. Kivshar

Publications and source records attributed to Yuri S. Kivshar.

At least 145 records · Page 8Linked to original sources

arXiv2011

Metamaterials with conformational nonlinearity

Within a decade of fruitful developments, metamaterials became a prominent area of research, bridging theoretical and applied electrodynamics, electrical engineering and material science. Being man-made structures, metamaterials offer a particularly useful playground to develop novel interdisciplinary concepts. Here we demonstrate a novel principle in metamaterial assembly which integrates electromagnetic, mechanical, and thermal responses within their elements. Through these mechanisms, the conformation of the meta-molecules changes, providing a dual mechanism for nonlinearity and offering nonlinear chirality. Our proposal opens a wide road towards further developments of nonlinear metamaterials and photonic structures, adding extra flexibility to their design and control.

physics.optics↗

arXiv2011

An arrayed nanoantenna for broadband light emission and detection

We suggest a broadband optical unidirectional arrayed nanoantenna consisting of equally spaced nanorods of gradually varying length. Each nanorod can be driven by near-field quantum emitters radiating at different frequencies or, according to the reciprocity principle, by an incident light at the same frequency. Broadband unidirectional emission and reception characteristics of the nano-antenna open up novel opportunities for subwavelength light manipulation and quantum communication, as well as for enhancing the performance of photoactive devices such as photovoltaic detectors, light-emitting diodes, and solar cells.

physics.optics↗

arXiv2011

Light propagation and localization in modulated photonic lattices and waveguides

We review both theoretical and experimental advances in the recently emerged physics of modulated photonic lattices. Artificial periodic dielectric media, such as photonic crystals and photonic lattices, provide a powerful tool for the control of the fundamental properties of light propagation in photonic structures. Photonic lattices are arrays of coupled optical waveguides, where the light propagation becomes effectively discretized. Such photonic structures allow one to study many useful optical analogies with other fields, such as the physics of solid state and electron theory. In particular, the light propagation in periodic photonic structures resembles the motion of electrons in a crystalline lattice of semiconductor materials. The discretized nature of light propagation gives rise to many new phenomena which are not possible in homogeneous bulk media, such as discrete diffraction and diffraction management, discrete and gap solitons, and discrete surface waves. Recently, it was discovered that applying periodic modulation to a photonic lattice by varying its geometry or refractive index is very much similar to applying a bias to control the motion of electrons in a crystalline lattice. An interplay between periodicity and modulation in photonic lattices opens up unique opportunities for tailoring diffraction and dispersion properties of light as well as controlling nonlinear interactions.

physics.optics↗

arXiv2011

Laser Pulse Heating of Spherical Metal Particles

We consider a general problem of laser pulse heating of spherical metal particles with the sizes ranging from nanometers to millimeters. We employ the exact Mie solutions of the diffraction problem and solve heat-transfer equations to determine the maximum temperature at the particle surface as a function of optical and thermometric parameters of the problem. The main attention is paid to the case when the thermometric conductivity of the particle is much larger than that of the environment, as it is in the case of metal particles in fluids. We show that in this case at any given finite duration of the laser pulse the maximum temperature rise as a function of the particle size reaches an absolute maximum at a certain finite size of the particle, and we suggest simple approximate analytical expressions for this dependence which covers the entire range of variations of the problem parameters and agree well with direct numerical simulations.

physics.optics↗

arXiv2011

Magnetoelastic nonlinear metamaterials

We introduce the concept of magnetoelastic metamaterials with electromagnetic properties depending on elastic deformation. We predict a strong nonlinear and bistable response of such metamaterials caused by their structural reshaping in response to the applied electromagnetic field. In addition, we demonstrate experimentally the feasibility of the predicted effect.

physics.optics↗

arXiv2011

Spontaneous radiation of a finite-size dipole emitter in hyperbolic media

We study the radiative decay rate and Purcell effect for a finite-size dipole emitter placed in a homogeneous uniaxial medium. We demonstrate that the radiative rate is strongly enhanced when the signs of the longitudinal and transverse dielectric constants of the medium are opposite, and the isofrequency contour has a hyperbolic shape. We reveal that the Purcell enhancement factor remains finite even in the absence of losses, and it depends on the emitter size.

physics.optics↗

arXiv2011

Generation and near-field imaging of Airy surface plasmons

We demonstrate experimentally the generation and near-field imaging of nondiffracting surface waves - plasmonic Airy beams, propagating on the surface of a gold metal film. The Airy plasmons are excited by an engineered nanoscale phase grating, and demonstrate significant beam bending over their propagation. We show that the observed Airy plasmons exhibit self-healing properties, suggesting novel applications in plasmonic circuitry and surface optical manipulation.

physics.optics↗

arXiv2011

Nonlinear Breathing-like Localized Modes in C60 Nanocrystals

We study the dynamics of nanocrystals composed of C60 fullerene molecules. We demonstrate that such structures can support long-lived strongly localized nonlinear oscillatory modes, which resemble discrete breathers in simple lattices. We reveal that at room temperatures the lifetime of such nonlinear localized modes may exceed tens of picoseconds; this suggests that C60 nanoclusters should demonstrate anomalously slow thermal relaxation when the temperature gradient decays in accord to a power law, thus violating the Cattaneo-Vernotte law of thermal conductivity.

cond-mat.mes-hall↗

arXiv2011

Enhanced emission and light control with tapered plasmonic nanoantennas

We introduce a design of Yagi-Uda plasmonic nanoantennas for enhancing the antenna gain and achieving control over the angular emission of light. We demonstrate that tapering of antenna elements allows to decrease spacing between the antenna elements tenfold also enhancing its emission directivity. We find the optimal tapering angle that provides the maximum directivity enhancement and the minimum end-fire beamwidth.

physics.optics↗

arXiv2011

Nonlinearly-PT-symmetric systems: spontaneous symmetry breaking and transmission resonances

We introduce a class of PT-symmetric systems which include mutually matched nonlinear loss and gain (inother words, a class of PT-invariant Hamiltonians in which both the harmonic and anharmonic parts are non-Hermitian). For a basic system in the form of a dimer, symmetric and asymmetric eigenstates, including multistable ones, are found analytically. We demonstrate that, if coupled to a linear chain, such a nonlinear PT-symmetric dimer generates new types of nonlinear resonances, with the completely suppressed or greatly amplified transmission, as well as a regime similar to the electromagnetically-induced transparency (EIT). The implementation of the systems is possible in various media admitting controllable linear and nonlinear amplification of waves.

math-ph↗

arXiv2011

Engineered Optical Nonlocality in Nanostructured Metamaterials

We analyze dispersion properties of metal-dielectric nanostructured metamaterials. We demonstrate that, in a sharp contrast to the results for the corresponding effective medium, the structure demonstrates strong optical nonlocality due to excitation of surface plasmon polaritons that can be engineered by changing a ratio between the thicknesses of metal and dielectric layers. In particular, this nonlocality allows the existence of an additional extraordinary wave that manifests itself in the splitting of the TM-polarized beam scattered at an air-metamaterial interface.

physics.optics↗

arXiv2010

Polychromatic nanofocusing of surface plasmon polaritons

We introduce the concept of polychromatic plasmonics and suggest an broadband plasmonic lens for nanofocusing of surface plasmon polaritons. The lens employs a parabolically modulated metal-dielectric-metal structure. This plasmonic lens has a bandwidth of more than an optical octave thus opening new opportunities for broadband plasmonic applications.

physics.optics↗

arXiv2010

Effects of polarization on the transmission and localization of classical waves in weakly scattering metamaterials

We summarize the results of our comprehensive analytical and numerical studies of the effects of polarization on the Anderson localization of classical waves in one-dimensional random stacks. We consider homogeneous stacks composed entirely of normal materials or metamaterials, and also mixed stacks composed of alternating layers of a normal material and metamaterial. We extend the theoretical study developed earlier for the case of normal incidence [A. A. Asatryan et al, Phys. Rev. B 81, 075124 (2010)] to the case of off-axis incidence. For the general case where both the refractive indices and layer thicknesses are random, we obtain the long-wave and short-wave asymptotics of the localization length over a wide range of incidence angles (including the Brewster ``anomaly'' angle). At the Brewster angle, we show that the long-wave localization length is proportional to the square of the wavelength, as for the case of normal incidence, but with a proportionality coefficient substantially larger than that for normal incidence. In mixed stacks with only refractive-index disorder, we demonstrate that p-polarized waves are strongly localized, while for s-polarization the localization is substantially suppressed, as in the case of normal incidence. In the case of only thickness disorder, we study also the transition from localization to delocalization at the Brewster angle.

cond-mat.dis-nn↗

arXiv2010

Electromagnetic wave analogue of electronic diode

An electronic diode is a nonlinear semiconductor circuit component that allows conduction of electrical current in one direction only. A component with similar functionality for electromagnetic waves, an electromagnetic isolator, is based on the Faraday effect of the polarization state rotation and is also a key component of optical and microwave systems. Here we demonstrate a chiral electromagnetic diode, which is a direct analogue of an electronic diode: its functionality is underpinned by an extraordinary strong nonlinear wave propagation effect in the same way as electronic diode function is provided by a nonlinear current characteristic of a semiconductor junction. The effect exploited in this new electromagnetic diode is an intensity-dependent polarization change in an artificial chiral metamolecule. This microwave effect exceeds a similar optical effect previously observed in natural crystals by more than 12 orders of magnitude and a direction-dependent transmission that differing by a factor of 65.

physics.optics↗

arXiv2010

Nonlinear suppression of time-reversals in PT-symmetric optical couplers

We reveal a generic connection between the effect of time-reversals and nonlinear wave dynamics in systems with parity-time (PT) symmetry, considering a symmetric optical coupler with balanced gain and loss where these effects can be readily observed experimentally. We show that for intensities below a threshold level, the amplitudes oscillate between the waveguides, and the effects of gain and loss are exactly compensated after each period due to {periodic time-reversals}. For intensities above a threshold level, nonlinearity suppresses periodic time-reversals leading to the symmetry breaking and a sharp beam switching to the waveguide with gain. Another nontrivial consequence of linear PT-symmetry is that the threshold intensity remains the same when the input intensities at waveguides with loss and gain are exchanged.

physics.optics↗

arXiv2010

Metamaterial tuning by manipulation of near-field interaction

We analyze the near-field interaction between the resonant sub-wavelength elements of a metamaterial, and present a method to calculate the electric and magnetic interaction coefficients. We show that by adjusting the relative configuration of the neighboring split ring resonators it becomes possible to manipulate this near-field interaction, and thus tune the response of metamaterials. We use the results of this analysis to explain the experimentally observed tuning of microwave metamaterials.

physics.optics↗

arXiv2010

Rotational tuning of interaction in metamaterials

We experimentally observe the tuning of metamaterials through the relative rotation of the elements about their common axis. In contrast to previous results we observe a crossing of resonances, where the symmetric and anti-symmetric modes become degenerate. We associate this effect with an interplay between the magnetic and electric near-field interactions and verify this by calculations based on the interaction energy between resonators.

physics.optics↗

arXiv2010

All-optical switching of dark states in nonlinear coupled microring resonators

We propose and analyze an on-chip all-optical dynamical tuning scheme for coupled nonlinear resonators employing a single control beam injected in parallel with a signal beam. We show that nonlinear Kerr response can be used to dynamically switch the spectral properties between "dark-state" and electromagnetically-induced transparency configurations. Such scheme can be realized in integrated optical applications for pulse trapping and delaying.

physics.optics↗