Showing papers by "Yuri S. Kivshar published in 2014"
TL;DR: Enhanced third-harmonic generation from silicon nanodisks exhibiting both electric and magnetic dipolar resonances is observed and the field localization at the magnetic resonance results in two orders of magnitude enhancement of the harmonic intensity with respect to unstructured bulk silicon.
Abstract: We observe enhanced third-harmonic generation from silicon nanodisks exhibiting both electric and magnetic dipolar resonances. Experimental characterization of the nonlinear optical response through third-harmonic microscopy and spectroscopy reveals that the third-harmonic generation is significantly enhanced in the vicinity of the magnetic dipole resonances. The field localization at the magnetic resonance results in two orders of magnitude enhancement of the harmonic intensity with respect to unstructured bulk silicon with the conversion efficiency limited only by the two-photon absorption in the substrate.
556 citations
TL;DR: An overview of the research on nonlinear electromagnetic metamaterials can be found in this article, where the developed theoretical approaches and experimental designs are summarized along with a systematic description of various phenomena available with nonlinear metammaterials.
Abstract: This Colloquium presents an overview of the research on nonlinear electromagnetic metamaterials The developed theoretical approaches and experimental designs are summarized, along with a systematic description of various phenomena available with nonlinear metamaterials
371 citations
TL;DR: The proposed concept of metamaterial-based subwavelength interconnection and polarization-controlled signal routing is based on the photonic spin Hall effect and may serve as an ultimate platform for either conventional or quantum electromagnetic signal processing.
Abstract: Metamaterials enable the control and manipulation of light on subwavelength scales, allowing numerous optical device applications. Here, the authors show the selective excitation of spatially confined modes in an anisotropic hyperbolic metamaterial, based on the photonic spin Hall effect.
262 citations
TL;DR: In the version of this Review published in print, "Si/Ge (ref. 23)" was listed on the eight line of the second column on the second page (page 949) as discussed by the authors.
Abstract: Nature Photon. 7, 948–957 (2013); published online 28 November 2013; corrected after print 28 November 2013. In the version of this Review published in print, “Si/Ge (ref. 23)” was listed on the eight line of the second column on the second page (page 949). This should have read “Ag/Ge (ref. 23)”. This error has been corrected in both the HTML and PDF versions of the Review.
181 citations
TL;DR: The novel concept of superdirective nanoantennas based on the excitation of higher-order magnetic multipole moments in subwavelength dielectric nanoparticles are introduced, and it is revealed that the nanoantenna's high directivity is not associated with strong localization of near fields in the regime of reception.
Abstract: We introduce the novel concept of superdirective nanoantennas based on the excitation of higher-order magnetic multipole moments in subwavelength dielectric nanoparticles. Our superdirective nanoantenna is a small Si nanosphere containing a notch, and is excited by a dipole located within the notch. In addition to extraordinary directivity, this nanoantenna demonstrates efficient radiation steering at the nanoscale, resulting from the subwavelength sensitivity of the beam radiation direction to variation of the source position inside the notch. We compare our dielectric nanoantenna with a plasmonic nanoantenna of similar geometry, and reveal that the nanoantenna's high directivity in the regime of transmission is not associated with strong localization of near fields in the regime of reception. Likewise, the absence of hot spots inside the nanoantenna leads to low dissipation in the radiation regime, so that our dielectric nanoantenna has significantly smaller losses and high radiation efficiency of up to 70%.
177 citations
TL;DR: Pronounced Fano resonances are observed for a variety of lithographically-fabricated heptamer nanostructures consisting of a central particle of varying size, encircled by six nanoparticles of constant size as a result of interference of the optically-induced magnetic dipole modes of the central particle with the collective mode of the nanoparticle structure.
Abstract: I t is well-known that oligomers made of metallic nanoparticles are able to support sharp Fano resonances originating from the interference of two plasmonic resonant modes with different spectral width. While such plasmonic oligomers suffer from high dissipative losses, a new route for achieving Fano resonances in nanoparticle oligomers has opened up after the recent experimental observations of electric and magnetic resonances in low-loss dielectric nanoparticles. Here, light scattering by all-dielectric oligomers composed of silicon nanoparticles is studied experimentally for the fi rst time. Pronounced Fano resonances are observed for a variety of lithographically-fabricated heptamer nanostructures consisting of a central particle of varying size, encircled by six nanoparticles of constant size. Based on a full collective mode analysis, the origin of the observed Fano resonances is revealed as a result of interference of the optically-induced magnetic dipole mode of the central particle with the collective mode of the nanoparticle structure. This allows for effective tuning of the Fano resonance to a desired spectral position by a controlled size variation of the central particle. Such optically-induced magnetic Fano resonances in all-dielectric oligomers offer new opportunities for sensing and nonlinear applications.
173 citations
TL;DR: In this article, a simple realization of topological edge states in zigzag chains of plasmonic nanoparticles, mimicking the Kitaev model of Majorana fermions, was proposed.
Abstract: We propose a simple realization of topological edge states in zigzag chains of plasmonic nanoparticles, mimicking the Kitaev model of Majorana fermions We demonstrate the one-to-one correspondence between the coupled dipole equations in the zigzag plasmonic chain and the Bogoliubov-de-Gennes equations for the quantum wire on top of superconductor and support the analytical theory by the full-wave electromagnetic simulations We reveal that localized plasmons can be excited selectively at both edges of the zigzag chain of plasmonic nanoparticles depending on the incident plane wave polarization
145 citations
TL;DR: A concept of "magnetoelectric energy density" is put forward, quantifying the local PT symmetry of the field, which is responsible for electric-magnetic asymmetry, chirality, and the nonreciprocal magnetoelectrics effect in nanoparticles or molecules.
Abstract: We study the generic dipole interaction of a monochromatic free-space electromagnetic field with a bi-isotropic nanoparticle or a molecule Contributions associated with the breaking of dual, P, and T symmetries are responsible for electric-magnetic asymmetry, chirality, and the nonreciprocal magnetoelectric effect, respectively We calculate absorption rates, radiation forces, and radiation torques for the nanoparticle and introduce novel field characteristics quantifying the transfer of energy, momentum, and angular momentum due to the three symmetry-breaking effects In particular, we put forward a concept of "magnetoelectric energy density," quantifying the local PT symmetry of the field Akin to the "superchiral" light suggested recently for local probing of molecular chirality, here we suggest employing complex fields for a sensitive probing of the nonreciprocal magnetoelectric effect in nanoparticles or molecules
132 citations
TL;DR: In this paper, the authors present a comprehensive analytical theory of localized nonlinear excitations supported by an incoherently pumped, spatially homogeneous exciton-polariton condensate.
Abstract: We present a comprehensive analytical theory of localized nonlinear excitations---dark solitons---supported by an incoherently pumped, spatially homogeneous exciton-polariton condensate. We show that, in contrast to dark solitons in conservative systems, these nonlinear excitations ``relax'' by blending with the background at a finite time, which critically depends on the parameters of the condensate. Our analytical results for trajectory and lifetime are in excellent agreement with direct numerical simulations of the open-dissipative mean-field model. In addition, we show that transverse instability of quasi-one-dimensional dark stripes in a two-dimensional open-dissipative condensate demonstrates features that are entirely absent in conservative systems, as creation of vortex-antivortex pairs competes with the soliton relaxation process.
98 citations
TL;DR: In this article, a hybrid metal-dielectric nano-antenna consisting of a gold nanorod and a silicon nanodisk was proposed to achieve a giant enhancement of directional emission together with simultaneously high radiation efficiency.
Abstract: Plasmonic and dielectric nanoparticles offer complementary strengths regarding their use as optical antenna elements. While plasmonic nanoparticles are well-known to provide strong decay rate enhancement for localized emitters, all-dielectric nanoparticles can enable high directivity combined with low losses. Here, we suggest a hybrid metal-dielectric nanoantenna consisting of a gold nanorod and a silicon nanodisk, which combines all these advantages. Our numerical analysis reveals a giant enhancement of directional emission together with simultaneously high radiation efficiency (exceeding 70%). The suggested hybrid nanoantenna has a subwavelength footprint, and all parameters and materials are chosen to be compatible with fabrication by two-step electron-beam lithography.
89 citations
TL;DR: In this paper, the dispersion characteristics of coupled-resonator optical waveguides were analyzed by means of the coupled-dipole approximation and then verified the validity of the model by comparing the results with direct numerical simulations.
Abstract: We study waveguiding of the electromagnetic energy below the diffraction limit with arrays of dielectric nanoparticles through the excitation of both electric and magnetic Mie resonances. We analyze the dispersion characteristics of such coupled-resonator optical waveguides by means of the coupled-dipole approximation and then verify the validity of the coupled-dipole model by comparing the results with direct numerical simulations. We reveal that a chain of silicon nanoparticles with realistic material losses can guide light for the distances exceeding several tens of micrometers, which is significantly better than the guiding by any plasmonic waveguide with the propagation distances less than 1 $\ensuremath{\mu}$m. We verify the main concept and our theoretical findings experimentally at microwaves for an array of ceramic particles.
TL;DR: In this article, the authors demonstrate the phase-locked interference of different multipolar moments within a single resonance for chiral light emission from quantum dots over split-ring resonant nanoantennas.
Abstract: We demonstrate nanoscale spin control of photons emitted by an atomic system coupled to a compact plasmonic nanoantenna supporting phase-locked interference of different multipolar moments within a single resonance. Experimentally we observe chiral light emission from quantum dots over split-ring resonant nanoantennas, where the spin of the emitted photons is locked to their transverse momentum. We demonstrate that the polarization can vary from linear to elliptical with ellipticity reaching ±0.5 for emission into opposite halves of the symmetry plane of the nanoantenna.
TL;DR: In this article, Iorsh and Shadrivov this article discussed the benefits of using Graphene Flagship (Contract No. CNECT-ICT-604391) under the FEDER COMPTETE Program and the Portuguese Foundation for Science and Technology (FCT).
Abstract: Y.V.B. thanks the Nonlinear Physics Center at the Australian National University for warm hospitality during his visit at the initial stage of this project. This work was partially supported by the FEDER COMPTETE Program and by the Portuguese Foundation for Science and Technology (FCT) through Grant PEst-C/FIS/UI0607/2013. We acknowledge a support from the EC under Graphene Flagship (Contract No. CNECT-ICT-604391). The authors thank I. Iorsh and I. Shadrivov for useful discussions.
TL;DR: In this paper, a ring of six ceramic spheres with and without a central particle was studied and it was shown that both structures exhibit resonant suppression of the forward scattering associated with the Fano resonance originated from the excitation of magnetic dipole modes.
Abstract: We demonstrate experimentally Fano resonances in all-dielectric oligomers clusters of dielectric particles. We study two structures consisting of a ring of six ceramic spheres with and without a central particle and demonstrate that both structures exhibit resonant suppression of the forward scattering associated with the Fano resonance originated from the excitation of magnetic dipole modes. By employing the near-field measurement techniques, we establish the relation between near- and far-field properties of the Fano resonances and identify directly their origin. We support our findings by an analytical approach based on the discrete-dipole approximation and find an excellent agreement with the experimental data.
TL;DR: In this paper, a genetic algorithm was used to optimize the scattering cross section of plasmonic nanowires for superscattering and cloaking at different wavelengths in the visible spectral range.
Abstract: We analyse scattering of light from multi-layer plasmonic nanowires and employ a genetic algorithm for optimizing the scattering cross section. We apply the mode-expansion method using experimental data for material parameters to demonstrate that our genetic algorithm allows designing realistic core-shell nanostructures with the superscattering effect achieved at any desired wavelength. This approach can be employed for optimizing both superscattering and cloaking at different wavelengths in the visible spectral range.
TL;DR: In this article, a nonlinear optical chip that generates photons with reconfigurable nonclassical spatial correlations is demonstrated, where photon pairs are generated through spontaneous parametric down-conversion and simultaneously spread through quantum walks between the waveguides.
Abstract: We demonstrate a nonlinear optical chip that generates photons with reconfigurable nonclassical spatial correlations. We employ a quadratic nonlinear waveguide array, where photon pairs are generated through spontaneous parametric down-conversion and simultaneously spread through quantum walks between the waveguides. Because of the quantum interference of these cascaded quantum walks, the emerging photons can become entangled over multiple waveguide positions. We experimentally observe highly nonclassical photon-pair correlations, confirming the high fidelity of on-chip quantum interference. Furthermore, we demonstrate biphoton-state tunability by spatial shaping and frequency tuning of the classical pump beam.
TL;DR: In this article, nonlinear properties of a multi-layer stack of graphene sheets are studied and the existence of single and multi-hump dissipative solitons in the graphene structure is predicted.
Abstract: Nonlinear properties of a multi-layer stack of graphene sheets are studied. It is predicted that such a structure may support dissipative plasmon-solitons generated and supported by an external laser radiation. Novel nonlinear equations describing spatial dynamics of the nonlinear plasmons driven by a plane wave in the Otto configuration are derived and the existence of single and multi-hump dissipative solitons in the graphene structure is predicted.
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TL;DR: In this paper, the suppression of light scattering for any direction of observation can be achieved for an uniform dielectric object with high refractive index, in a sharp contrast to the cloaking with multilayered plasmonic structures suggested previously.
Abstract: Subwavelength structures demonstrate many unusual optical properties which can be employed for engineering functional metadevices, as well as scattering of light and invisibility cloaking. Here we demonstrate that the suppression of light scattering for any direction of observation can be achieved for an uniform dielectric object with high refractive index, in a sharp contrast to the cloaking with multilayered plasmonic structures suggested previously. Our finding is based on the novel physics of cascades of Fano resonances observed in the Mie scattering from a homogeneous dielectric rod. We observe this effect experimentally at microwaves by employing high temperature-dependent dielectric permittivity of a glass cylinder with heated water. Our results open a new avenue in analyzing the optical response of hight-index dielectric nanoparticles and the physics of cloaking.
TL;DR: It is shown that chiral symmetry breaking can be found in the stationary response of the system, which provides a new possibility for creating an artificial phase transition in metamaterials, analogous to that in ferrimagnetic domains.
Abstract: Spontaneous symmetry breaking is one of the unusual effects offered by nonlinear metamaterials. Here, the authors study this effect in chiral magnetoelastic metamaterials where the meta-molecules of opposite handedness are both electromagnetically and mechanically coupled.
TL;DR: In this paper, the basic physics of Airy plasmons in both paraxial and non-paraxial cases, and the experimental methods for generation of airy surface waves on metal surfaces are described.
Abstract: Airy beams represent an important class of non-diffracting waves which can be realized on a flat surface. Being generated in the form of surface-plasmon polaritons, such Airy plasmons demonstrate many remarkable properties: they do not diffract while propagating along parabolic trajectories, and they recover their shape after passing through obstacles. This paper reviews the basic physics of Airy plasmons in both paraxial and non-paraxial cases, and describes the experimental methods for generation of Airy surface waves on metal surfaces, including a control of their trajectories, as well as the interference of Airy plasmons and hot-spot generation. Many unusual properties of Airy plasmons can be utilized for useful applications, including plasmonic circuitry and surface tweezers. Picture: Observation of two colliding Airy plasmons.
TL;DR: In this article, the authors measured the near-field amplitudes and phases of localized optical modes of high-index all-dielectric nanoparticles using apertureless near field optical microscopy.
Abstract: We measure, for the first time to our knowledge, the near-field amplitudes and phases of localized optical modes of high-index all-dielectric nanoparticles using apertureless near-field optical microscopy. For individual silicon nanodisks, we observe a four-lobed mode pattern and the formation of deep-subwavelength hot-spots. Our numerical calculations of the optical near-fields of the nanodisks in combination with a multipole expansion of the scattered field based on vector spherical harmonics reveal that the observed modes are dominated by electric quadrupole contributions. The observed mode is of particular interest for the design of low-loss all-dielectric metasurfaces and nanoantennas for a broad range of applications, such as directional and complex-polarization controlled emission, light extraction from multipolar atomic transitions, and coherent multiple-emitter-nanocavity interactions.
TL;DR: In this paper, the second-harmonic generation by a spherical dielectric nanoparticle covered by graphene was studied and it was shown that a strong nonlinear response is caused by an induced surface current in the graphene nanoparticle illuminated by an external electromagnetic wave.
Abstract: We study the second-harmonic generation by a spherical dielectric nanoparticle covered by graphene. We demonstrate that a strong nonlinear response is caused by an induced surface current in the graphene nanoparticle illuminated by an external electromagnetic wave. We obtain analytical expressions for the field multipoles characterizing the second-harmonic radiation and analyze the dependence of intensity and directivity of the nonlinear scattering on the frequency and structure of the electromagnetic field, revealing the asymmetric radiation patterns due to constructive multipole interference for the resonantly enhanced second-harmonic generation.
TL;DR: In this paper, the authors review the recent progress in this research direction of nanoparticle scattering shaping and control through the interference of both electric and optically-induced magnetic responses, and discuss the magnetic resonances supported by various structures in different spectral regimes.
Abstract: Conventional approaches to control and shape the scattering patterns of light generated by different nanostructures are mostly based on engineering of their electric response due to the fact that most metallic nanostructures support only electric resonances in the optical frequency range. Recently, fuelled by the fast development in the fields of metamaterials and plasmonics, artificial optically-induced magnetic responses have been demonstrated for various nanostructures. This kind of response can be employed to provide an extra degree of freedom for the efficient control and shaping of the scattering patterns of nanoparticles and nanoantennas. Here we review the recent progress in this research direction of nanoparticle scattering shaping and control through the interference of both electric and optically-induced magnetic responses. We discuss the magnetic resonances supported by various structures in different spectral regimes, and then summarize the original results on the scattering shaping involving both electric and magnetic responses, based on the interference of both spectrally separated (with different resonant wavelengths) and overlapped dipoles (with the same resonant wavelength), and also other higher-order modes. Finally, we discuss the scattering control utilizing Fano resonances associated with the magnetic responses.
TL;DR: In this article, a simple approach for achieving superdirectivity of emitted radiation for electrically small antennas based on a spherical dielectric resonator with a notch excited by a dipole source was proposed.
Abstract: We propose and demonstrate experimentally a simple approach for achieving superdirectivity of emitted radiation for electrically small antennas based on a spherical dielectric resonator with a notch excited by a dipole source. Superdirectivity is achieved without using complex antenna arrays and for a wide range of frequencies. We also demonstrate the steering effect for a subwavelength displacement of the source. Finally, unlike previously known superdirective antennas, our design has significantly smaller losses, at the operation frequency radiation efficiency attains 80%, and matching holds in the 3%-wide frequency band without any special matching technique.
TL;DR: The concept of the split-ball resonator is introduced and the strong magnetic response in the visible for both gold and silver spherical plasmonic nanoparticles with nanometre scale cuts is demonstrated.
Abstract: Engineering the magnetic and electric dipole resonances in nanostructures offers unique material applications. Kuznetsov et al. show that by tuning the depth and width of a nanometre scale cut in a metallic nanosphere, they can tune the magnetic resonance across the visible spectral range.
TL;DR: In this article, a two-layer metamaterial with hybrid elements composed of twisted pairs of cross-shaped meta-atoms and their complements was studied and a retrieval procedure was developed to determine the effective material parameters for this structure.
Abstract: We study theoretically and experimentally a type of metamaterial with hybrid elements composed of twisted pairs of cross-shaped meta-atoms and their complements. We reveal that such two-layer metasurfaces demonstrate large, dispersionless optical activity at the transmission resonance accompanied by very low ellipticity. We develop a retrieval procedure to determine the effective material parameters for this structure, which has symmetry (C4 )o f a lower order than other commonly studied chiral structures. We verify our theoretical approach by reproducing
TL;DR: In this article, a free-floating resonant nanoparticle in a subwavelength plasmonic V-groove waveguide was used to control light with light.
Abstract: In order to achieve interaction between light beams, a mediating material object is required. Nonlinear materials are commonly used for this purpose. Here a new approach to control light with light, based on a nano-opto-mechanical system integrated in a plasmonic waveguide is proposed. Optomechanics of a free-floating resonant nanoparticle in a subwavelength plasmonic V-groove waveguide is studied. It is shown that nanoparticle auto-oscillations in the waveguide induced by a control light result in the periodic modulation of a transmitted plasmonic signal. The modulation depth of 10% per single nanoparticle of 25 nm diameter with the clock frequencies of tens of MHz and the record low energy-per-bit energies of 10−18 J is observed. The frequency of auto-oscillations depends on the intensity of the continuous control light. The efficient modulation and deep-subwavelength dimensions make this nano-optomechanical system of significant interest for opto-electronic and opto-fluidic technologies.
TL;DR: In this paper, an alternative approach for realizing subwavelength photonic structures, exploiting the waveguiding properties of chains of high-index dielectric disks with both electric and magnetic dipole resonances, was proposed and demonstrated experimentally.
Abstract: We propose and demonstrate experimentally an alternative approach for realizing subwavelength photonic structures, exploiting the waveguiding properties of chains of high-index dielectric disks with both electric and magnetic dipole resonances. We reveal that the electromagnetic energy can be efficiently guided through sharp corners by means of the mode polarization conversion at waveguide bends. We confirm experimentally the guidance through a 90° bend in the microwave frequency range.
TL;DR: In this paper, the dispersion properties of TM-polarized electromagnetic waves guided by a multilayer graphene metamaterial were studied and it was shown that both dispersion and localization of the guided modes can be efficiently controlled by changing the number of layers in the structure.
Abstract: We study dispersion properties of TM-polarized electromagnetic waves guided by a multilayer graphene metamaterial. We demonstrate that both dispersion and localization of the guided modes can be efficiently controlled by changing the number of layers in the structure. Remarkably, we find that in the long wavelength limit, the dispersion of the fundamental mode of the N-layer graphene structure coincides with the dispersion of a plasmon mode supported by a single graphene layer, but with N times larger conductivity. We also compare our exact dispersion relations with the results provided by the effective media model.
TL;DR: This work derives general coupled-mode equations describing the nonlinear interaction of electromagnetic modes in periodic media with loss and gain based on the Lorentz reciprocity theorem and predicts novel effects on self- and cross-phase modulation in multilayer nonlinear fishnet metamaterials.
Abstract: We derive general coupled-mode equations describing the nonlinear interaction of electromagnetic modes in periodic media with loss and gain. Our approach is rigorously based on the Lorentz reciprocity theorem, and it can be applied to a broad range of metal–dielectric photonic structures, including plasmonic waveguides and metamaterials. We verify that our general results agree with the previous analysis of particular cases, and predict novel effects on self- and cross-phase modulation in multilayer nonlinear fishnet metamaterials.