Metasurfaces, composed of subwavelength scattering elements, have demonstrated remarkable control over the transmitted amplitude, phase, and polarization of light. However, manipulating the amplitude upon transmission has required loss if a single metasurface is used. Here, we describe high-efficiency independent manipulation of the amplitude and phase of a beam using two lossless phase-only metasurfaces separated by a distance. With this configuration, we experimentally demonstrate optical components such as combined beam-forming and splitting devices, as well as those for forming complex-valued, three-dimensional holograms. The compound meta-optic platform provides a promising approach for achieving high performance optical holographic displays and compact optical components, while exhibiting a high overall efficiency.
All-dielectric metamaterials consisting of high-dielectric inclusions in a low-dielectric matrix are considered as a low-loss alternative to resonant metal-based metamaterials. In this contribution we investigate the applicability of the point electric and magnetic dipoles approximation to dielectric meta-atoms on the example of a dielectric ring metamaterial. Despite the large electrical size of high-dielectric meta-atoms, the dipole approximation allows for accurate prediction of the metamaterials properties for the rings with diameters up to ~0.8 of the lattice constant. The results provide…
The absorption of electromagnetic radiation by a planar structure, consisting of a three-layer dielectric-metal-dielectric coating on a metal back-reflector is analysed. The conditions for total absorption are derived. Our analysis shows that, in contrast with bi-layer structures, the calculated layer thicknesses are feasible to fabricate for any metal. The proposed absorber design is of potential use in infrared and longer wavelength detectors and for radiant energy harvesting devices.
All-dielectric metamaterials composed of high index and low loss dielectric resonators have become a promising way for high-efficient optical devices. However, fabricating terahertz all-dielectric metamaterials and actively tuning their properties still remain challenges. In this paper, an effective method has been developed to prepare high-quality microspheres based all-dielectric metamaterial operating in terahertz (THz) range. Then, we propose a magnetically tunable THz all-dielectric metamaterial based on liquid crystal (LC). The all-dielectric metamaterial is immersed into LC and tuned by…
We introduce a practical dielectric metasurface design for microwave frequencies. The metasurface is made of an array of dielectric resonators held together by dielectric connections thus avoiding the need of a mechanical support in the form of a dielectric slab and the spurious multiple reflections that such a slab would generate. The proposed design can be used either for broadband metasurface applications or monochromatic wave transformations. The capabilities of the concept to manipulate the transmission phase and amplitude of the metasurface are supported by numerical and experimental res…
We present effective optical constants of stratified metal-dielectric metameterial. The effective constants are determined by two complex reflectivity method (TCRM). TCRM reveals full components of effective permittivity and permeability tensors and indicates the remarkable anisotropy of metallic and dielectric components below effective plasma frequency. On the other hand, above the plasma frequency, one of the effective refractive indexes takes a positive value less than unity and is associated with small loss. The photonic states are confirmed by the distribution of electromagnetic fields.
Metamaterials-or artificial electromagnetic materials-can create media with properties unattainable in nature, but mitigating dissipation is a key challenge for their further development. Here, we demonstrate a low-loss metamaterial by exploiting dark bound states in dielectric inclusions coupled to the external waves by small nonresonant metallic antennas. We experimentally demonstrate a dispersion-engineered metamaterial based on a meta-atom made from alumina, and we show that its resonance has a much larger quality factor than metal-based meta-atoms. Finally, we show that our dielectric met…
We demonstrate, for the first time, an all-dielectric metamaterial resonator in the mid-wave infrared based on high-index tellurium cubic inclusions. Dielectric resonators are desirable compared to conventional metallo-dielectric metamaterials at optical frequencies as they are largely angular invariant, free of ohmic loss, and easily integrated into three-dimensional volumes. With these low-loss, isotropic elements, disruptive optical metamaterial designs, such as wide-angle lenses and cloaks, can be more easily realized.
Metamaterials comprising assemblies of dielectric resonators have attracted much attention due to their low intrinsic loss and isotropic optical response. In particular, metasurfaces made from silicon dielectric resonators have shown desirable behaviors such as efficient nonlinear optical conversion, spectral filtering and advanced wave-front engineering. To further explore the potential of dielectric metamaterials, we present all-dielectric metamaterials fabricated from epitaxially grown III-V semiconductors that can exploit the high second-order optical susceptibilities of III-V semiconducto…
In this paper, we derive a model from Maxwell equations for the magnetic resonance of split-ring resonators. Using this model we revisit the scaling of split-ring resonators. Inspired by our model, we propose a new type of split-hybrid metal-dielectric ring resonator, of which the ring is made composed of moderately high index dielectric material (e.g. SiC, TiO2, ZnS) (for the major portion), while and metal (e.g. Ag) fills the gap. Such a new magnetic metamaterial is able to overcome the saturation problem of split-ring resonatorssaturation-free and therefore is able to operate at short wavel…
We study in detail a novel type of optical nanoantennas made of high-permittivity low-loss dielectric particles. In addition to the electric resonances, the dielectric particles exhibit very strong magnetic resonances at the nanoscale, that can be employed in the Yagi-Uda geometry for creating highly efficient optical nanoantennas. By comparing plasmonic and dielectric nanoantennas, we demonstrate that all-dielectric nanoantennas may exhibit better radiation efficiency also allowing more compact design.
We theoretically demonstrate mechanical tuning of the spectral response of a Mie-like resonant dielectric metasurface consisting of crossed all-dielectric strip gratings. We use two array of parallel dielectric strips superimposed on each other to mechanically alter the crossing angle between them thereby changing the position of the maximum of the spectral response in a wide frequency range. The metasurface structure is considered as a doubly-periodic system in an oblique mesh. This mechanically controllable metasurface can be perspective in developing of a flexible polarization-sensitive opt…
We report the realization of spin-dependent splitting with arbitrary intensity patterns based on all-dielectric metasurface. Compared to the plasmonic metasurfaces, the all-dielectric metasurface exhibit more high transmission efficiency and conversion efficiency, which make it is possible to achieve the spin-dependent splitting with arbitrary intensity patterns. Our findings suggest a way for generation and manipulation of spin photons, and thereby offer the possibility of developing spin-based nanophotonic applications.
The concept of the broadband epsilon-near-zero meta-atom consisting of layered stacks with specified metallic filling ratio and thickness is proposed based on the Bergman spectral representation of the effective permittivity. The step-like metal-dielectric multilayer structures are designed to achieve realistic broadband epsilon-near-zero meta-atoms in optical frequency range. These meta-atoms can be integrated as building blocks for unconventional optical components with exotic electromagnetic properties over a wide frequency range, such as the demonstrated broadband directional emission and …
We report the design of highly efficient optical antennas employing a judicious synthesis of metallic and dielectric materials. In the proposed scheme, a pair of metallic coupled nanoparticles permits large enhancements in both excitation strength and radiative decay rates, while a high refractive index dielectric microsphere is employed to efficiently collect light without spoiling the emitter quantum efficiency. Our simulations indicate potential fluorescence rate enhancements of 3 orders of magnitude over the entire optical frequency range.
A hybrid plasmonic-dielectric metasurface is proposed in order to manipulate beam propagation in desired manners. The metasurface is composed of patterned hybrid graphene-silicon nano-disks deposited on a low-index substrate, namely silica. It is shown that the proposed hybrid metasurface simultaneously benefits from the advantages of graphene-based metasurfaces and dielectric ones. Specially, we show that the proposed hybrid metasurface not only provides reconfigurability, just like previously proposed graphene-based metasurfaces, but also similar to dielectric metasurfaces it is low loss and…
Subwavelength-thin metasurfaces have shown great promises for the control of optical wavefronts, thus opening new pathways for the development of efficient flat optics. In particular, Huygens' metasurfaces based on all-dielectric resonant meta-atoms have already shown a huge potential for practical applications with their polarization insensitivity and high transmittance efficiency. Here, we experimentally demonstrate a polarization insensitive holographic Huygens' metasurface based on dielectric resonant meta-atoms capable of complex wavefront control at telecom wavelengths. Our metasurface p…
Photonic components based on structured metallic elements show great potential for device applications where field enhancement and confinement of the radiation on a subwavelength scale is required. In this paper we report a detailed study of a prototypical metallo-dielectric photonic structure, where features well known in the world of dielectric photonic crystals, like band gaps and defect modes, are exported to the metallic counterpart, with interesting applications to infrared science and technology, as for instance in quantum well infrared photodetectors, narrow-band spectral filters, and …
We present an experimental and theoretical study of the optical properties of metal-dielectric-metal structures with patterned top metallic surfaces, in the THz frequency range. When the thickness of the dielectric slab is very small with respect to the wavelength, these structures are able to support strongly localized electromagnetic modes, concentrated in the subwavelength metal-metal regions. We provide a detailed analysis of the physical mechanisms which give rise to these photonic modes. Furthermore, our model quantitatively predicts the resonance positions and their coupling to free spa…
We investigated numerically the electromagnetically induced transparency (EIT) behavior with the maximum Q factor is up to 28000 in a metal-dielectric metamaterial. It composed of two layers, a metallic strip as bright mode stacked above a dielectric rod as another bright mode. The coherent coupling between the broad electric dipole induced by the metal strip and the narrow toroidal dipole induced by the dielectric rod leads to the destructive interference, then introduces a transparency window. Interestingly, the EIT window could be effectively influenced by varying parameters of the two laye…
We theoretically investigate the spontaneous emission process of an optical, dipolar emitter in metal-dielectric-metal slab and slot waveguide structures. We find that both structures exhibit strong off-resonant emission enhancements due to the tight confinement of modes between two metallic plates. The large enhancement of surface plasmon-polariton excitation enables dipole emission to be preferentially coupled into plasmon waveguide modes. These structures find applications in creating nanoscale local light sources or in generating guided single plasmons in integrated optical circuits.
We present an initial study of the angular spectrum of a bianisotropic refractive metasurface at an interface between two dielectric media. In this study, we report on the existence of three distinct angular regions: a)~a rotated transmission cone, b)~a modified total internal reflection region, and c)~a new total retro-reflection region.
By harnessing the resonant nature of localized electromagnetic modes in a nanostructured silicon membrane, an all-dielectric metamaterial can act as nonlinear medium at optical telecommunications wavelengths. We show that such metamaterials provide extremely large optomechanical nonlinearities, operating at intensities of only a few μW per unit cell and modulation frequencies as high as 152 MHz, thereby offering a path to fast, compact and energy efficient all-optical metadevices.
We demonstrate the active tuning of all-dielectric metasurfaces exhibiting high-quality factor (high-Q) resonances. The active control is provided by embedding the asymmetric silicon meta-atoms with liquid crystals, which allows the relative index of refraction to be controlled through heating. It is found that high quality factor resonances ($Q=270\pm30$) can be tuned over more than three resonance widths. Our results demonstrate the feasibility of using all-dielectric metasurfaces to construct tunable narrow-band filters.
Metasurfaces are two-dimensional optical structures enabling complete control of the amplitude, phase, and polarization of light. Unlike plasmonic metasurfaces, planar silicon structures facilitate high transmission, low losses and compatibility with existing semiconductor technologies. Here, we report an experimental demonstration of high-efficiency polarization- sensitive dielectric metasurfaces with full 2pi phase control in transmission mode at telecommunication wavelengths. Such silicon metasurfaces are poised to enable a versatile optical platform the realization of all-optical circuitry…
Previous formulations of transformation optics have generally been restricted to transformations from relatively simple initial media, such as the vacuum, because of limitations due to their non-covariance. I show that a completely covariant approach enables arbitrary transformations from arbitrarily complex initial linear dielectrics.
In this paper, super-focusing using radiationless electromagnetic interference is extended to the visible regime. It is shown that the highest-order mode of a specifically designed metal-dielectric waveguide array can provide the rapidly oscillating source field for radiationless interference. Using finite-difference time-domain simulations, an example structure is demonstrated. This structure provides focusing to 0.21 of the optical wavelength at a distance of half the optical wavelength from the source.
We demonstrate that spectrally diverse multiple magnetic dipole resonances can be excited in all-dielectric structures lacking rotational symmetry, in contrast to conventionally used spheres, disks or spheroids. Such multiple magnetic resonances arise from hybrid Mie-Fabry-Pérot modes, and can constructively interfere with induced electric dipole moments, thereby leading to novel multi-frequency unidirectional scattering. Here we focus on elongated dielectric nanobars, whose magnetic resonances can be spectrally tuned by their aspect ratios. Based on our theoretical results, we suggest all-die…
A single-order transmission diffraction grating based on dispersion engineered all-dielectric metasurfaces is proposed and its wavelength discriminating properties have been theoretically described and confirmed using numerical simulations. The metasurface is designed using a 2D array of all-dielectric resonators, which emulates a Huygens source configuration to achieve a perfect match to free-space in broad bandwidth. Using a holey dielectric nanodisk structure as the unit cell, the resonant wavelength is tapered across the metasurface to engineer the wavelength dependent spatial phase gradie…
We reveal peculiarities of the trapped (dark) mode excitation in a polarization-insensitive all-dielectric metasurface, whose unit super-cell is constructed by particularly arranging four cylindrical dielectric particles. Involving group-theoretical description we discuss in detail the effect of different orientations of particles within the super-cell on characteristics of the trapped mode. The theoretical predictions are confirmed by numerical simulations and experimental investigations. Since the metasurface is realized from simple dielectric particles without the use of any metallic compon…
We investigate optical (transverse gradient) forces between two high-index dielectric planar waveguides immersed in low-index dielectric fluid media. Complimentary to previous studies, we extend optical forces calculations, in order to take into account a non-vacuum (and non-air) background medium, by using the Minkowski stress tensor formulation; we derived a very simple set of equations in terms of the effective refractive indexes of the waveguide eigenmodes. We also used a normalized version of the dispersion relation method to calculate the optical forces, in order to validate our results …
We demonstrate how to create all-dielectric metasurfaces with a strong toroidal response by arranging two types of nanodisks into asymmetric quadrumer clusters. We demonstrate that a strong axial toroidal response of the metasurface is related to conditions of the trapped (dark) mode that is excited due the symmetry breaking in the cluster. We study the correlation between the toroidal response and asymmetry in the metasurface and nanocluster geometries, which appears from the different diameters of nanodisks or notches introduced into the nanodisks.
Metasurfaces are planar optical elements that hold promise for overcoming the limitations of refractive and conventional diffractive optics1-3. Dielectric metasurfaces demonstrated thus far4-10 are limited to transparency windows at infrared wavelengths because of significant optical absorption and loss at visible wavelengths. It is critical that new materials and fabrication techniques be developed for dielectric metasurfaces at visible wavelengths to enable applications such as three-dimensional displays, wearable optics and planar optical systems11. Here, we demonstrate high performance tit…
Artificial metasurfaces are capable of completely manipulating the phase, amplitude, and polarization of light with high spatial resolutions. The emerging design based on high-index and low-loss dielectrics has led to the realization of novel metasurfaces with high transmissions, but these devices usually operate at the limited bandwidth, and are sensitive to the incident polarization. Here, for the first time we report experimentally the polarization-independent and high-efficiency dielectric metasurfaces spanning the visible wavelengths about 200 nm, which are of importance for novel flat op…
We show that a nonlinear metallo-dielectric layered slab of subwavelength thickness and very small average dielectric permittivity displays optical multistable behavior at arbitrary low optical intensities. This is due to the fact that, in the presence of the small linear permittivity, one of the multiple electromagnetic slab states exists no matter how small is the transmitted optical intensity. We prove that multiple states at ultra-low optical intensities can be reached only by simultaneously operating on the incident optical intensity and incidence angle. By performing full wave simulation…
Metadevices based on dielectric nanostructured surfaces with both electric and magnetic Mie-type resonances have resulted in the best efficiency to date for functional flat optics with only one disadvantage: a narrow operational bandwidth. Here we experimentally demonstrate broadband transparent all-dielectric metasurfaces for highly efficient polarization manipulation. We utilize the generalized Huygens principle, with a superposition of the scattering contributions from several electric and magnetic multipolar modes of the constituent meta-atoms, to achieve destructive interference in reflec…
Metasurfaces providing resonances arising from quasi-bound states in the continuum have been proposed as sensors in the THz band due to the existence of strong resonances characterized by high quality factors. Controlling geometrical parameters, the quality factor can be adjusted and, theoretically, designed at will. However, losses in materials critically bound the metasurface performance and limit the quality factor of the resonances. For this reason, all-dielectric metasurfaces have been proposed as an alternative to metal-dielectric structures to reduce losses and achieve extreme functiona…
All-dielectric resonant nanophotonics lies at the heart of modern optics and nanotechnology due to the unique possibilities to control scattering of light from high-index dielectric nanoparticles and metasurfaces. One of the important concepts of dielectric Mie-resonant nanophotonics is associated with the Kerker effect that drives the unidirectional scattering of light from nanoantennas and Huygens' metasurfaces. Here we suggest and demonstrate experimentally a novel effect manifested in the nearly complete simultaneous suppression of both forward and backward scattered fields. This effect is…
We demonstrate theoretically a large transverse magneto-optical Kerr effect (TMOKE) in subwavelength gratings consisting of alternating magneto-insulating and nonmagnetic dielectric nanostripes. The reflectivity of the grating reaches $96\%$ at the frequencies corresponding to the maximum of the TMOKE response. The combination of a large TMOKE response and high reflectivity is important for applications in $3$D imaging, magneto-optical data storage, and magnonics.
All-dielectric resonant nanophotonics is a rapidly developing research field driven by its exceptional application potential for low-loss nanoscale metadevices. The tight confinement of the local electromagnetic fields and interferences in resonant photonic nanostructures can boost many optical effects, thus offering novel opportunities for the subwavelength control of light-matter-interactions. Active, light-emitting nanoscale structures are of particular interest, as they offer unique opportunities for novel types of light sources and nanolasers. Here, we review the latest advances in this r…
Based on full-wave scattering theory with self-consistent mean field approximation, we study the optical multi-stability of graphene-wrapped dielectric nanoparticles. We demonstrate that the optical bistability (OB) of the graphene-wrapped nanoparticle exist in both near-field and far-field spectra, and show the optical multi-stability arising from the contributions of higher-order terms of the incident external field. Moreover, both the optical stable region and the switching threshold values can be tuned by changing either the Fermi level or the size of the nanoparticle. Our results promise …
We show that a stack of metal-dielectric nanolayers, in addition to the long- and short-range plasmons, guides also an entire family of modes strongly confined within the multilayer - the bulk plasmon modes. We propose the classification scheme that reflects specific properties of these modes. We report experimental verification of the bulk plasmon modes by measuring modal indices in a structure made of three pairs of silica(29nm)/gold(25nm) layers.
High-index dielectric materials are in great demand for nanophotonic devices and applications, from ultrathin optical elements to metal-free sub-diffraction light confinement and waveguiding. Here we show that chalcogenide topological insulators are particularly apt candidates for dielectric nanophotonic architectures in the infrared spectral range by reporting metamaterial resonances in chalcogenide crystals sustained well inside the mid-infrared, choosing Bi$_2$Te$_3$ as case study within this family of materials. Strong resonant modulation of the incident electromagnetic field is achieved t…
We introduce transversely structured all-dielectric waveguides which exploit the vectorial nature of light to achieve extreme sub-wavelength confinement in high index dielectrics, enabling characteristic mode dimensions below $λ_0^2$/1,000 without metals or plasmonics. We also derive the metric of optical concentration and show its convenient usage in characterizing enhanced linear and non-linear interactions at the nanoscale. This work expands the toolbox of nanophotonics and opens the door to new types of ultra-efficient and record performing linear and nonlinear devices with broad applicati…
We propose to use femtosecond direct laser writing technique to realize dielectric optical elements from photo-resist materials for the generation of structured light from purely geometrical phase transformations. This is illustrated by the fabrication and characterization of spin-to-orbital optical angular momentum couplers generating optical vortices of topological charge from 1 to 20. In addition, the technique is scalable and allows obtaining microscopic to macroscopic flat optics. These results thus demonstrate that direct 3D photopolymerization technology qualifies for the realization of…
In this Letter we theoretically study a novel approach for soliton-induced supercontinuum generation based on the application of metallic dielectric-coated hollow waveguides. Low loss of such waveguides permits the use of smaller diameters with enhanced dispersion control and enables the generation of two-octave-broad spectra with unprecedentedly high spectral peak power densities up to five orders of magnitude larger than in standard PCFs with high coherence. We also predict that high-power supercontinua in the vacuum ultraviolet can be generated in such waveguides.
Specially designed metal-dielectric composites can have a negative refractive index in the optical range. Specifically, it is shown that arrays of single and paired nanorods can provide such negative refraction. For pairs of metal rods, a negative refractive index has been observed at 1.5 micrometer. The inverted structure of paired voids in metal films may also exhibit a negative refractive index. A similar effect can be accomplished with metal strips in which the refractive index can reach -2. The refractive index retrieval procedure and the critical role of light phases in determining the r…
Subwavelength dielectric resonators assembled into metasurfaces have become a versatile tool for miniaturising optical components approaching the nanoscale. An important class of metasurface functionalities is associated with asymmetry in both generation and transmission of light with respect to reversals of the positions of emitters and receivers. Nonlinear light-matter interaction in metasurfaces offers a promising pathway towards miniaturisation of the asymmetric control of light. Here we demonstrate asymmetric parametric generation of light in nonlinear metasurfaces. We assemble dissimilar…
We study optical wave manipulations through high-index dielectric metalattices in both diffractionless metasurface and diffractive metagrating regimes. It is shown that the collective lattice couplings can be employed to tune the excitation efficiencies of all electric and magnetic multipoles of various orders supported by each particle within the metalattice. The interferences of those adjusted multipoles lead to highly asymmetric angular scattering patterns that are totally different from those of isolated particles, which subsequently enables flexible beam manipulations, including perfect r…
We theoretically study the role of nonlinear surface plasmoms on the optical bistability of graphene-wrapped dielectric cylinders, within the framework of both full-wave scattering theory and the quasistatic limit. Typical hysteresis curves are observed in both near-field and far-field spectra. Moreover, we demonstrate that introducing the full wave theory results in another bistable behavior with a high applied electromagnetic field, suggesting a more explicit way in analyzing the unstable behavior of the graphene-wrapped dielectric cylinder. Furthermore, optical stable region and the switchi…
We demonstrate numerically the diffraction-free propagation of sub-wavelength sized optical beams through simple elements built of metal-dielectric multilayers. The proposed metamaterial consists of silver and a high refractive index dielectric, and is designed using the effective medium theory as strongly anisotropic and impedance matched to air. Further it is characterised with the transfer matrix method, and investigated with FDTD. The diffraction-free behaviour is verified by the analysis of FWHM of PSF in the function of the number of periods. Small reflections, small attenuation, and red…
We experimentally demonstrate orbiting of isotropic, dielectric microparticles around an optical nanofiber that guides elliptically polarized fundamental modes. The driving transverse radiation force appears in the evanescent electromagnetic fields due to orbital angular momentum. The force direction is opposite to that of the energy flow circulation around the nanofiber. Our results verify the theoretically predicted negative optical torque on a sufficiently large particle in the vicinity of a nanofiber.
Dielectric metasurfaces with spatially varying birefringence and high transmission efficiency can exhibit exceptional abilities for controlling the photonic spin states. We present here some of our works on spin photonics and spin-photonic devices with metasurfaces. We develop a hybrid-order Poincare sphere to describe the evolution of spin states of wave propagation in the metasurface. Both the Berry curvature and the Pancharatnam-Berry phase on the hybrid-order Poincare sphere are demonstrated to be proportional to the variation of total angular momentum. Based on the spin-dependent property…
Nonlinear Pancharatnam-Berry phase metasurfaces facilitate the nontrivial phase modulation for frequency conversion processes by leveraging photon-spin dependent nonlinear geometric-phases. However, plasmonic metasurfaces show some severe limitation for nonlinear frequency conversion due to the intrinsic high ohmic loss and low damage threshold of plasmonic nanostructures. Here, we systematically study the nonlinear geometric-phases associated with the third-harmonic generation process occurring in all-dielectric metasurfaces, which are composed of silicon nanofins with different in-plane rota…
During the past few years, metasurfaces have been used to demonstrate optical elements and systems with capabilities that surpass those of conventional diffractive optics. Here we review some of these recent developments with a focus on dielectric structures for shaping optical wavefronts. We discuss the mechanisms for achieving steep phase gradients with high efficiency, simultaneous polarization and phase control, controlling the chromatic dispersion, and controlling the angular response. Then we review applications in imaging, conformal optics, tunable devices, and optical systems. We concl…
We analyze the impact of nonlocality on the waveguide modes of metallo-dielectric multilayers and optical patch antennas, the latter formed from metal strips closely spaced above a metallic plane. We model both the nonlocal effects associated with the conduction electrons of the metal, as well as the previously overlooked response of bound electrons. We show that the fundamental mode of a metal-dielectric-metal waveguide, sometimes called the gap-plasmon, is very sensitive to nonlocality when the insulating, dielectric layers are thinner than 5 nm. We suggest that optical patch antennas, which…
We theoretically investigate general existence conditions for broadband bulk large-wavevector (high-k) propagating waves (such as volume plasmon polaritons in hyperbolic metamaterials) in subwavelength periodic multilayer structures. Describing the elementary excitation in the unit cell of the structure by a generalized resonance pole of a reflection coefficient, and using Bloch's theorem, we derive analytical expressions for the band of large-wavevector propagating solutions. We apply our formalism to determine the high-k band existence in two important cases: the well-known metal-dielectric,…
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.
Tunable dielectric meta-surface nanostructures offer incredible performance in optical application due to their extraordinary tunability of the polarization and engineering the dispersion of light with low loss in infrared range. In this article, we designed and experimentally measured the tunability of all-dielectric subwavelength silicon nanoparticles with the help of the temperature-based refractive index of the liquid crystal in the telecom regime. The proposed structure composed of high dielectric nanodisk surrounded by nematic liquid crystal (NLC) is simulated with numerical software, as…
