Metal-dielectric Resonator Research Articles

COMPARATIVE EVALUATION OF THE STRUCTURAL DESIGN OF MICROWAVE CONVECTIVE HOP DRYERS

In hop production, the main scientific problem is the low energy efficiency of hop dryers with convective heat supply and the absence of small-sized mobile continuous-flow hop dryers for farms that ensure the preservation of the consumer properties of hops at reduced operating costs. In order to reduce the operating costs of drying hops, work is being carried out aimed at clarifying the drying modes that contribute to the best preservation of consumer characteristics, and the improvement of technologies and technical means that would reduce operating costs. A new method of drying hops by ultra-high-frequency energy supply deserves attention. (Research purpose) The research purpose is revealing the effectiveness of an ultrahigh-frequency convective hop dryer of continuous-flow action by evaluating the developed structural designs of hop dryers with metal-dielectric resonators that ensure uniform drying and disinfection of freshly harvested hops and electromagnetic safety without a shielding housing at reduced operating costs in the conditions of hop farms. (Materials and methods) Carried out three-dimensional modeling of the structural designs of hop dryers in the Compass 20 program, determined the electrodynamic parameters of the ”generator-resonator“ system in CST Microwave Studio. (Results and discussion) Solved the problem of optimizing the structural design and dimensions of metal-electric resonators. It was shown that the main criteria are the correctly agreed parameters of the electrodynamic system ”generator-resonator“: the intrinsic Q-factor of the resonator, the voltage of the electric field, its uniformity of distribution, the power of the radiation flux, the volume of the resonator. The electro-dynamic parameters of 11 hop dryers with different designs of resonators were analyzed: hemispherical, semi-cylindrical, cylindrical, toroidal, prismatic, ellipsoid and others. (Conclusions) It was found that toroidal and hemispherical resonators have a maximum intrinsic Q-factor of up to 8000. It was determined during the evaluation of deviations from the average value of the intervals of variation of the criteria that hop dryers with resonators in the form of a paraboloid and hyperboloid, and semi-cylindrical, are effective.

SCIENTIFIC AND TECHNICAL BASIS FOR THE DEVELOPMENT OF INSTALLATIONS WITH MICROWAVE POWER SUPPLY FOR PROCESSING RAW MATERIALS AT AGRICULTURAL ENTERPRISES

The developed methodology of designing installations with microwave power supply for heat treatment of raw materials of agricultural enterprises is described. The scientific problem is the low energy efficiency of installations designed for heat treatment of raw materials with steam-water mixture, convective heat supply, the absence of continuous-flow installations for farms that ensure the preservation of consumer properties of the heat-treated product at reduced operating costs. (Research purpose) The research purpose is developing the scientific and technical foundations of installations with microwave power supply for processing raw materials at agricultural enterprises. (Materials and methods) Carried out three-dimensional modeling of the structural design of the installations in the Compass 20 program, determined the electrodynamic parameters of the “generator-resonator” system in the CST Microwave Studio program. (Results and discussion) Resonators of different structural designs have been developed for different types of raw materials, in which electromagnetic safety is ensured by forbidden waveguides, decelerating systems in the form of a chain of connected resonators, comb, cylindrical spiral, rod ring, counter pins. In resonators with curved surfaces, several magnetrons of the same frequency or operating at close frequencies with dissectors were used to change the frequency of the generator and increase the number of types of vibrations, and mixing, transporting mechanisms that allow maintaining the well of the technological process less than 0.5 and observing the dimensions of the raw materials in accordance with the depth of penetration of the wave. It was found that when using several magnetrons, the concentration of the electromagnetic field energy in the resonator volume and the reduction of radiation losses are achieved using ceramic reflectors. The values of the intrinsic Q-values of the resonators were determined to evaluate the thermal efficiency coefficient. (Conclusions) Using the examples of an animal colostrum defroster, instant milk pasteurizer and a three-section hop dryer with air-cooled magnetrons, the implementation of the scientific and technical fundamentals of designing microwave equipment for processing raw materials of agricultural enterprises was shown. It was revealed that they provide ways to achieve a continuous mode of operation of the equipment in compliance with electromagnetic safety without a shielding housing by implementing metal-dielectric resonators with decelerating systems and ceramic reflectors with an optimal arrangement of waveguides with air-cooled magnetrons on the curved surfaces of the resonators.

ИНТЕНСИФИКАЦИЯ ПРОЦЕССА ИЗВЛЕЧЕНИЯ ЖИРА ИЗ ЖИРОСОДЕРЖАЩЕГО СЫРЬЯ ДИЭЛЕКТРИЧЕСКИМ НАГРЕВОМ

The article substantiates the effective modes of heat treatment of fat-containing raw materials in a radiohermatic ultrahigh-frequency installation with a metal-dielectric resonator.
 The raw material for the study was the internal fat of cattle, sheep, chickens, their dielectric characteristics were systematized according to I.A. Rogov.
 The purpose of this work is to develop a continuous-flow microwave installation with air-cooled magnetrons and a resonator in the form of a truncated cone with an exponential generator, which contributes to increasing thermal efficiency and maintaining high electric field strength and radio tightness without a shielding housing when heating disinfected fat from fat-containing raw materials. The electrophysical parameters of the fat-containing raw material are analyzed, including the change in dielectric parameters from the frequency of the electromagnetic field (EMF), fat content, density. The intensity of the electric field is matched with the heating rate, the specific power of the generator. A continuous-flow microwave installation with a resonator in the form of a truncated cone with an exponential generator made of non-ferromagnetic material and a ceramic concave mirror base, inside of which a dielectric screw with a decreasing pitch and a diameter of a screw is located, has been developed. A concave ceramic mirror is installed coaxially on the large base of the resonator. A dielectric screw is inscribed along the resonator. Two sluice gates with non-magnetic bent blades are installed on the resonator. The melted fat flows down through the perforation on the surface of the resonator. Magnetrons with waveguides are installed with a shift of 120 degrees along the perimeter of the resonator base. The general properties of a resonator with dielectric inclusions (ceramic mirror, fluoro-formation auger) are analyzed. In such a metal-dielectric resonator, the reflection of the field from the non-magnetic walls of the resonator and critical sections can be combined with full internal reflection in the dielectric.
 The exponential generator of the resonator and the ceramic mirror contribute to an increase in the concentration of the electric field strength in it to 2 kV/cm when placing three magnetrons with a shift of 120 degrees along the perimeter of the large base. With a specific power of the generator of 2 W/g, the productivity of the microwave installation for heat treatment of fat-containing raw materials is 18-20 kg/h.; With a frequency of rotation of the electric screw drive of 1 rpm, 0.5-0.6 kg of raw materials is heated in 120 seconds. The specific energy costs compared to the prototype (0.2-0.25 kWh/kg) is reduced to 0.14-0.15 kWh/kg.

Justification of the parameters of a microwave installation with a metal-dielectric resonator for defrosting of colostrum of animals

The article is devoted to the substantiation of the structural performance of an ultra-high-frequency (UHF) installation of continuous flow action for defrosting and warming up animal colostrum. The dielectric parameters of colostrum in the frozen and liquid state were analyzed to determine the generated power and the depth of penetration of electromagnetic waves. For a given generator power, a threshold power that depends on the electric field strength (EF), and taking into account the change in the attenuation coefficient of electromagnetic waves during heating, a theoretical assessment of the optimal volume of raw materials in which animal colostrum is disinfected was carried out. These indicators are consistent with the design parameters of unconventional cavity resonators.

Photoplasmonic assembly of dielectric-metal, Nd2O3-Gold soret nanointerfaces for dequenching the luminophore emission

Abstract A variety of materials such as low dimensional carbon substrates (1D, 2D, and 3D), nanoprisms, nanocubes, proteins, ceramics, and DNA to name a few, have been explored in surface plasmon-coupled emission (SPCE) platform. While these offer new physicochemical insights, investigations have been limited to silver as primary plasmonic material. Although, gold nanoparticles (AuNPs) exhibit robust performance, its intrinsic property to quench the emission from radiating dipoles (at distances < 5 nm) has impeded its utility. Despite the use of metal-dielectric resonances (with Au decorated SiO2 NPs) and sharp nanotips (from Au nanostars) for dequenching the emission, the enhancements obtained has been less than 200-fold in SPCE platform. To address these long-standing challenges, we demonstrate the utility of gold soret colloids (AuSCs) and photonic crystal-coupled emission (PCCE) platform. The soret nano-assemblies synthesized using adiabatic cooling technique presented integrated hotspots when taken with high refractive index Nd2O3 ‘Huygens sources’. The collective and coherent coupling between localized Mie and delocalized Bragg plasmons (of sorets), dielectric plasmons (of Nd2O3), highly confined and intense Bloch surface waves (of PCCE platform) aided in realization of dequenched, as well as amplified > 1500-fold enhancements at the photoplasmonic nanocavity interface, presenting new opportunities for multidisciplinary applications.

Multifunctional hybrid soret nanoarchitectures for mobile phone-based picomolar Cu2+ ion sensing and dye degradation applications

The ability of nanoscale materials to trap electromagnetic field beyond the diffraction limit is seldom studied using multifunctional nanohybrids. To this end, we demonstrate a thermo-migratively assembled Soret nanoassembly that enable unique metal-metal, metal-graphene and metal-dielectric resonances. In contrast to the well-explored standalone plasmonic and dielectric platforms, the Soret colloids possess salient nanogaps that exhibit delocalized Bragg and localized Mie plasmon resonances with effective EM field confinement. Accordingly, the Soret colloids of silver metal with plasmonic NPs: platinum (AgPtSC), 2D material: graphene oxide (AgGOSC) and dielectric NPs: TiC (AgTiCSC), TiN (AgTiNSC) and TiCN (AgTiCNSC) comprehensively have been utilized to achieve >600-fold fluorescence enhancements. The ability to tailor the highly directional and p-polarized emission enhancements using these well-characterized multifunctional sorets has been experimentally demonstrated on surface plasmon-coupled emission (SPCE) platform. The mobile phone-based detection of environmentally relevant Cu 2+ ions in drinking water using AgPtSC presents low-cost, rapid, simple, sensitive and reliable sensing strategy for Cu 2+ ion monitoring in resource-limited settings. Further, dye-degradation of xenobiotic pollutants for environmental remediation presents multifarious applications with these nano-architectures. This study opens a new window to explore synergy of nanomaterials constituting elements from different parts of periodic table to accomplish essential properties for desired applications. The hybrid multifunctional soret colloids assisting metal-metal, metal-dielectric and metal-π-plasmon resonances are most suitable candidates for plasmonic as well as xenobiotic dye degradation applications. Mobile phone-based surface plasmon-coupled emission platform was utilized for sensing Cu 2+ ions at picomolar concentration. • An adiabatic cooling based synthesis of hybrid multifunctional soret nanoassembly. • Utility of synergistic metal-metal, metal-dielectric and metal-π-plasmon resonances. • Multifold hot-spots from localized and delocalized plasmons of nanohybrids in SPCE. • Enhanced 600-fold polarized SPCE for mobile phone-based picomolar Cu 2+ ion sensing. • Xenobiotic degradation using π-plasmon and electron relay in hybrid silver sorets.

Method for measuring the Q-factor of miniature open dielectric resonators at ultrahigh frequencies

A simple algorithm for reliably determining the Q-factor of an open dielectric resonator made of a material with a tgδ less than 0.0001 in the shielded region is presented, based on measuring the parameters of an electromagnetically coupled system of bulk metal and open dielectric resonators. The analytical substantiation of the considered method for determining the Q-factor of an open dielectric resonator in electrodynamic and electrotechnical representations is carried out. The variants of the influence of the metal volume on the effective Q-factor of an open dielectric resonator depending on its electrophysical characteristics are considered. The factors affecting the effective Q-factor of an open dielectric resonator obtained using this measurement method are evaluated, and the range of expected measurement errors is shown. The advantage of the method for determining the Q-factor of an open dielectric resonator is the high accuracy of the obtained analytical ratios for determining the Q-factor, the absence of increased requirements for the accuracy of the measurement sections and the quality of the internal surfaces of the metal resonator, the simplicity of the measurement process, based on the use of ordinary equipment and element base.

Hyperbolic metamaterial-based metal–dielectric resonator-antenna designs for GHz photon collection rates from wide-range solid-state single-photon sources

Solid-state single-photon sources (SPS) based on quantum dots as well as color centers in diamonds and silicon-carbide have promise for application in emerging quantum technologies. Many of these technologies, however, demand photon rates in the GHz range, thereby hindering the use of these SPS, for which the maximum observed count rates are limited to a few tens of MHz. Here we first study the performance of hyperbolic metamaterial-based 5-layered metal–dielectric resonator antenna structures with metallic as well as hybrid metal–dielectric antennas in the wavelength range of 600 to 1000 nm. The performance of these resonator-antenna structures was analyzed for the Purcell enhancement, quantum efficiency (QE), collection efficiency (CE), and normalized collected photon counts (NCPC). The hybrid metal–dielectric antenna helps in providing the directivity to the dipole emission, thereby significantly improving the collection efficiency. We then present the novel design of a 5-layered metal–dielectric pillar resonator. This resonator structure with a metallic cylindrical antenna over the top showed significantly large fluorescence enhancement values. The Purcell factor was observed to reach close to 1600 at 680 nm corresponding to the central peak of the nitrogen vacancy center spectrum. The NCPC value reached close to 550 at 680 nm. The maximum CE from the structure was observed to be around 60%, with the maximum QE reaching close to 80%. With the above performance, the detected photon count rates for a solid-state SPS is expected to be well into the GHz range. Our designs show a state-of-the-art improvement in the antenna performance for SPS with properties very close to a practical SPS.

Quantized quasinormal-mode description of nonlinear cavity-QED effects from coupled resonators with a Fano-like resonance

We employ a recently developed quantization scheme for quasinormal modes (QNMs) to study a nonperturbative open cavity-QED system consisting of a hybrid metal-dielectric resonator coupled to a quantum emitter. This hybrid cavity system allows one to explore the complex coupling between a low $Q$ (quality factor) resonance and a high $Q$ resonance, manifesting in a striking Fano resonance, an effect that is not captured by traditional quantization schemes using normal modes or a Jaynes-Cummings (JC) type model. The QNM quantization approach rigorously includes dissipative coupling between the QNMs, and is supplemented with generalized input-output relations for the output electric field operator for multiple modes in the system, and correlation functions outside the system. The role of the dissipation-induced mode coupling is explored in the strong coupling regime between the photons and emitter beyond the first rung of the JC dressed-state ladder. Important differences in the quantum master equation and input-output relations between the QNM quantum model and phenomenological dissipative JC models are found. In a second step, numerical results for the Fock distributions and system as well as output correlation functions obtained from the quantized QNM model for the hybrid structure are compared with results from a phenomenological approach. We demonstrate explicitly how the quantized QNM model manifests in multiphoton quantum correlations beyond what is predicted by the usual JC models.

Metal-dielectric optical resonance in metasurfaces and SERS effect

Anomalous optical response of the metasurface, fabricated from regular silicon resonators is investigated. The resonators have form of two-dimensional regular bars that are covered by nano-thin silver film. Computer simulations as well as real experiment demonstrate deep minima in the reflectance in the optical spectral range. We believe the resonances are due to the excitation of propagating and localized surface em waves. The multiple metal-dielectric resonances result in much enhanced local electromagnetic fields on the surface of the resonators. To investigate the surface enhanced Raman scattering (SERS) effect the metasurface is covered by molecules of 4-mercapto-phenylboronic acid that form covalent bonds with the silver layer. We obtain over $$10^5$$ enhancement of the Raman scattering, by direct matching Raman signals from the metasurface and the flat silver surface. The designed metasurface is used as an effective SERS substrate.

Molecular Optomechanics in the Anharmonic Cavity-QED Regime Using Hybrid Metal–Dielectric Cavity Modes

Using carefully designed hybrid metal-dielectric resonators, we study molecular optomechanics in the strong coupling regime ($g_{\rm }^2/\omega_m {>} \kappa$), which manifests in anharmonic emission lines in the sideband-resolved region of the cavity-emitted spectrum ($\kappa{<}\omega_m$). This nonlinear optomechanical strong coupling regime is enabled through a metal-dielectric cavity system that yields not only deep sub-wavelength plasmonic confinement, but also dielectric-like confinement times that are more than two orders of magnitude larger than those from typical localized plasmon modes. These hybrid metal-dielectric cavity modes enable one to study new avenues of quantum plasmonics for single molecule Raman scattering.

Light Concentration by Metal-Dielectric Micro-Resonators for SERS Sensing.

Metal-dielectric micro/nano-composites have surface plasmon resonances in visible and near-infrared domains. Excitation of coupled metal-dielectric resonances is also important. These different resonances can allow enhancement of the electromagnetic field at a subwavelength scale. Hybrid plasmonic structures act as optical antennae by concentrating large electromagnetic energy in micro- and nano-scales. Plasmonic structures are proposed for various applications such as optical filters, investigation of quantum electrodynamics effects, solar energy concentration, magnetic recording, nanolasing, medical imaging and biodetection, surface-enhanced Raman scattering (SERS), and optical super-resolution microscopy. We present the review of recent achievements in experimental and theoretical studies of metal-dielectric micro and nano antennae that are important for fundamental and applied research. The main impact is application of metal-dielectric optical antennae for the efficient SERS sensing.

Light localization and SERS in tip-shaped silicon metasurface.

Optical properties of two dimensional periodic system of the silicon micro-cones are investigated. The metasurface, composed of the silicon tips, shows enhancement of the local optical field. Finite element computer simulations as well as real experiment reveal anomalous optical response of the dielectric metasurface due to excitation of the dielectric resonances. Various electromagnetic resonances are considered in the dielectric cone. The metal-dielectric resonances, which are excited between metal nanoparticles and dielectric cones, are also considered. The resonance local electric field can be much larger than the field in the usual surface plasmon resonances. To investigate local electric field the signal molecules are deposited on the metal nanoparticles. We demonstrate enhancement of the electromagnetic field and Raman signal from the complex of DTNB acid molecules and gold nanoparticles, which are distributed over the metasurface. The metasurfaces composed from the dielectric resonators can have quasi-continuous spectrum and serve as an efficient SERS substrates.

Calculation of frequency and power characteristics of the composite metal-dielectric resonator using the method of partial regions

A new method for calculating the frequency and power characteristics of different modes of a microwave metal-dielectric resonator has been proposed. The results of measurements of experimental specimens are presented that are in good agreement with calculation results. The relationships of the frequency and power characteristics of a resonator as a function of its geometrical and electrophysical parameters were obtained by using the method of partial regions. A high sensitivity of the main mode resonant frequency to the thickness of air inhomogeneity was detected. In this case the introduction of inhomogeneity increases the resonator Q-factor. Thus, the proposed design can be used as a high-Q tunable resonator.

Quality Factor of Tunable Shielded Cylindrical Metal-Dielectric Reso-nator Caused by Dielectric Loss

Quality Factor of Tunable Shielded Cylindrical Metal-Dielectric Reso-nator Caused by Dielectric Loss

Hybrid metal-dielectric ring resonators for homogenizable optical metamaterials with strong magnetic response at short wavelengths down to the ultraviolet range

We derive an analytical LC model from Maxwell's equations for the magnetic resonance of subwavelength ring resonators. Using the LC model, we revisit the scaling of split-ring resonators. Inspired by the LC model, we propose a hybrid metal-dielectric ring resonator mainly composed of high index dielectric material (e.g., TiO₂) with some gaps filled with metal (e.g., Ag). The saturation frequency of magnetic response for the hybrid metal-dielectric ring resonator is much higher (up to the ultraviolet range) than that for split-ring resonators, and can be controlled by the metal fraction in the ring. The hybrid metal-dielectric ring resonator can also overcome the homogenization problem of all-dielectric magnetic resonators, and therefore can form homogenizable magnetic metamaterials at short wavelengths down to the ultraviolet range.

Optical detection of single non-absorbing molecules using the surface plasmon resonance of a gold nanorod

Existing methods for the optical detection of single molecules require the molecules to absorb light to produce fluorescence or direct absorption signals. This limits the range of species that can be detected, because most molecules are purely refractive. Metal nanoparticles or dielectric resonators can be used to detect non-absorbing molecules because local changes in the refractive index produce a resonance shift. However, current approaches only detect single molecules when the resonance shift is amplified by a highly polarizable label or by a localized precipitation reaction on the surface of a nanoparticle. Without such amplification, single-molecule events can only be identified in a statistical way. Here, we report the plasmonic detection of single molecules in real time without the need for labelling or amplification. Our sensor consists of a single gold nanorod coated with biotin receptors, and the binding of single proteins is detected by monitoring the plasmon resonance of the nanorod with a sensitive photothermal assay. The sensitivity of our device is ∼700 times higher than state-of-the-art plasmon sensors and is intrinsically limited by spectral diffusion of the surface plasmon resonance.

MoM volume Integral equation solution for an isolated metal-dielectric resonator with the edge-based basis functions

The objective of the present study is to show that the method of volume integral used in conjunction with the zeroth-order edge-based basis functions (de Carvalho and de Souza Mendes 1999) gives an accurate and stable solution for a metal-dielectric resonator, when the number of the basis functions remains relatively small. Special attention is paid to the resonator in the form of a thin dielectric layer backed by two metal sheets. The metal surface is described in terms of the Rao-Wilton-Glisson (RWG) basis functions.

Measuring the dielectric permittivity of sapphire at temperatures 93-343 K

We consider a method for measuring the elements of the dielectric-permittivity tensor of a slightly lossy uniaxial anisotropic dielectric using the spectrum of resonance frequencies of a metal-dielectric resonator in the form of an axially anisotropic cylindrical specimen with endface metal mirrors. Measurements of both elements of the dielectric-permittivity tensor of sapphire at temperatures 93–343 K are performed using the spectrum of symmetric E modes. To avoid the influence of the residual gaps between the specimen and the mirrors, the endface surfaces of the specimen are metallized. We performed independent measurements of the axial and transverse elements of the permittivity tensor at room temperature from the spectra of azimuthal E modes and symmetric H modes. The values of the axial and transverse elements of the dielectric-permittivity tensor of sapphire in the range 93–343 K are presented with a spacing of 10 K.

Excitation of Whispering-Gallery Type Oscillations in Quasi-Optical Metal-Dielectric Resonator by a Coupling Slot in the Mirror

Excitation of Whispering-Gallery Type Oscillations in Quasi-Optical Metal-Dielectric Resonator by a Coupling Slot in the Mirror