All-dielectric metamaterials: irrelevance of negative refraction to overlapped Mie resonances

All-dielectric metamaterials comprised of identical resonators draw a lot of attention as low-loss media providing for negative refraction, which is commonly attributed to the double negativity of effective material parameters caused by overlapping of Mie resonances. We study dispersion diagrams of such metamaterials composed of dielectric rod arrays and show that bandwidths of positive and negative refraction and its type are irrelevant to the negativity of effective parameters; instead, they are unambiguously defined by the shape and the location of the second transmission branch in dispersion diagrams and thus can be controlled by the lattice constants

Spatial dispersion of index components required for building invisibility cloak medium from photonic crystals

The opportunities to use dielectric photonic crystals (PhCs) as the media of cylindrical invisibility cloaks, designed using transformation optics (TO) concepts, are investigated. It is shown that TO-based prescriptions for radial index dispersion, responsible for turning waves around hidden objects, can be dropped if the PhC media support self-collimation of waves in bent crystals. Otherwise, to provide prescribed anisotropy of index dispersion, it is possible to employ PhCs with rectangular lattices. It is found, however, that at acceptable cloak thicknesses, modifications of crystal parameters do not allow for achieving the prescribed level of index anisotropy. This problem is solved by finding the reduced spatial dispersion law for the radial index component, which is characterized by decreased against TO-prescriptions values near the target and increased values in outer layers of the cloak. The cloak utilizing reduced prescriptions for indices is shown to perform almost as efficiently as a TO-based cloak, in terms of both wave front restoration behind the target and reducing the total scattering cross-width of the target

Sensing based on fano-type resonance response of all-dielectric metamaterials

A new sensing approach utilizing Mie resonances in metamaterial arrays composed of dielectric resonators is proposed. These arrays were found to exhibit specific, extremely high-Q factor (up to 15,000) resonances at frequencies corresponding to the lower edge of the array second transmission band. The observed resonances possessed with features typical for Fano resonances (FRs), which were initially revealed in atomic processes and recently detected in macro-structures, where they resulted from interference between local resonances and a continuum of background waves. Our studies demonstrate that frequencies and strength of Fano-type resonances in all-dielectric arrays are defined by interaction between local Mie resonances and Fabry-Perot oscillations of Bloch eigenmodes that makes possible controlling the resonance responses by changing array arrangements. The opportunity for obtaining high-Q responses in compact arrays is investigated and promising designs for sensing the dielectric properties of analytes in the ambient are proposed

Марганецсодержащие катализаторы переработки попутных нефтяных газов в олефины

Рассмотрены варианты процессов переработки попутных нефтяных газов в жидкие углеводородные топлива. Изучены окислительные превращения С1-С4-углеводородов в олефины на оксидных марганецсодержащих катализаторах в периодическом режиме. Перспективным направлением переработки попутного нефтяного газа можно считать двухстадийный процесс: первая стадия - синтез олефинов из С1-С4-углеводородов; вторая - конверсия непредельных углеводородов в моторные топлива

Dielectric Metamaterials and Metasurfaces in Transformation Optics and Photonics

Dielectric Metamaterials and Metasurfaces in Transformation Optics and Photonics addresses the complexity of electromagnetic responses from arrays of dielectric resonators, which are often omitted from consideration when using simplified metamaterials concepts. The book\u27s authors present a thorough consideration of dielectric resonances in different environments which is needed to design optical and photonic devices. Dielectric metamaterials and photonic crystals are compared, with their effects analyzed. Design approaches and examples of designs for invisibility cloaks based on artificial media are also included. Current challenge of incorporating artificial materials into transformation optics-based and photonics devices are also covered

Sensing Based on Fano-Type Resonance Response of All-Dielectric Metamaterials

A new sensing approach utilizing Mie resonances in metamaterial arrays composed of dielectric resonators is proposed. These arrays were found to exhibit specific, extremely high-Q factor (up to 15,000) resonances at frequencies corresponding to the lower edge of the array second transmission band. The observed resonances possessed with features typical for Fano resonances (FRs), which were initially revealed in atomic processes and recently detected in macro-structures, where they resulted from interference between local resonances and a continuum of background waves. Our studies demonstrate that frequencies and strength of Fano-type resonances in all-dielectric arrays are defined by interaction between local Mie resonances and Fabry-Perot oscillations of Bloch eigenmodes that makes possible controlling the resonance responses by changing array arrangements. The opportunity for obtaining high-Q responses in compact arrays is investigated and promising designs for sensing the dielectric properties of analytes in the ambient are proposed

Lattice Resonances in Metasurfaces Composed of Silicon Nano-Cylinders

We investigate lattice resonances (LRs) in metasurfaces (MSs), composed of silicon nano-cylinders. It is revealed that LRs can be detected through concentration of fields at specific locations in the gaps between nano-cylinders. Formation of LRs appears to significantly modify the resonance responses of MSs, transforming elementary responses into collective phenomena. Their contribution in red-shifting of resonances at increasing the lattice constants and in phenomena, associated with Rayleigh anomalies, are discussed