Pair Of Resonators Research Articles

Complete cycle of modeling and simulation for wireless power transfer using circuit theory, simple electronics, and open-source software

This article presents a complete modeling and simulation framework for a simple resonant inductive coupling circuit, composed of a pair of inductive resonators that can wirelessly transfer about 60 W of power at a distance of approximately 15 cm. The circuit was physically implemented, and the transmitting coil was powered by a simple half-bridge electronic circuit that generated a square voltage signal. Measurements were compared to simulation results, and it was found that the proposed model could accurately explain and predict the behavior of the circuit. Our results show that optimum transfer of power varies according to the load values, the fRequency and the distance between the transmitter and receiver, which can vary considerably depending on the application. Simulations using AC circuit analysis helped in depicting the behavior of the circuit under this kind of variability, and in characterizing the presence of the optimum points for power transfer, although these were attained at lower efficiency. The present analysis paves the way for further investigations using control theory to track the frequencies at which maximum power is delivered for each set of variables, i.e., the distance between the resonators and the load value.

Resonant light enhances phase coherence in a cavity QED simulator of fermionic superfluidity

Cavity QED experiments are natural hosts for non-equilibrium phases of matter supported by photon-mediated interactions. In this work, we consider a cavity QED simulation of the BCS model of superfluidity, by studying regimes where the cavity photons act as dynamical degrees of freedom instead of mere mediators of the interaction via virtual processes. We find an enhancement of long time coherence following a quench whenever the cavity frequency is tuned into resonance with the atoms. We discuss how this is equivalent to enhancement of non-equilibrium superfluidity and highlight similarities to an analogous phenomena recently studied in solid state quantum optics. We also discuss the conditions for observing this enhanced resonant pairing in experiments by including the effect of photon losses and inhomogeneous coupling in our analysis.

Exceptional Points in Parity--Time-Symmetric Subwavelength Metamaterials

When sources of energy gain and loss are introduced to a wave scattering system, the underlying mathematical formulation will be non-Hermitian. This paves the way for the existence of exceptional points, where eigenmodes are linearly dependent. The primary goal of this work is to study the existence of exceptional points in high-contrast subwavelength metamaterials. We begin by studying a parity--time-symmetric pair of subwavelength resonators and prove that this system supports asymptotic exceptional points. These are points at which the subwavelength eigenvalues and eigenvectors coincide at leading order in the asymptotic parameter. We then investigate the exotic scattering behavior of a metascreen composed of repeating parity-time-symmetric pairs of subwavelength resonators. We prove that the non-Hermitian nature of this structure means that it exhibits asymptotic unidirectional reflectionless transmission at certain frequencies and demonstrate extraordinary transmission close to these frequencies.

Metahouse: Noise‐Insulating Chamber Based on Periodic Structures

AbstractNoise pollution remains a challenging problem requiring the development of novel systems for noise insulation. Extensive work in the field of acoustic metamaterials has led to various ventilated structures which, however, are usually demonstrated for rather narrow regions of the audible spectrum. In this work, the idea of metamaterial‐based systems is further extended, developing the concept of a metahouse chamber representing a ventilated structure for multiple band noise insulation. Broad stop‐bands originate from strong coupling between pairs of Helmholtz resonators constituting the structure. The averaged transmission −18.6 dB are demonstrated numerically and experimentally within the spectral range from 1500 to 16 500 Hz. The sparseness of the structure together with the possibility to use optically transparent materials suggest that the chamber may be also characterized by partial optical transparency depending on the mutual position of structural elements. The obtained results are promising for development of novel noise‐insulating structures advancing urban science.

Broadband terahertz polarization conversion using a planar toroidal metamaterial

The development of metamaterial-based photonic components has acquired a significant interest in technological developments at terahertz frequencies. The manipulation of the state of polarization is an important parameter in optical devices. In this study, we have investigated, both numerically and experimentally, a toroidal excitation-based metamaterial that is capable of converting terahertz from its linearly polarized state to an orthogonally polarized state over a broad spectrum. The meta-molecule unit of the proposed geometry is comprised of a pair of resonators connected to each other having a split gap in each arm. We have studied both the horizontal and vertical components of transmission for numerous in-plane rotations of the proposed geometry. A multipolar analysis confirms a significant contribution of the toroidal component. Polarization conversion of nearly 40% is observed over a broad spectrum of 1.19–2.5 THz. Such a broadband cross-polarization converter could have remarkable implications for the development of terahertz toroidal metamaterial devices.

Acoustic embedded eigenstates in metasurface-based structures

Energy confinement plays an important role in improving wave–matter interactions, enabling applications such as sensing, lasing, and filtering. One convenient solution for achieving large energy-confinement is based on embedded eigenstates, i.e., non-radiating eigenmodes supported by open structures. While the analysis of these modes is quite consolidated in electromagnetics and optics, their relevance in acoustics has been less explored, despite their wide application potential. In this work, we explore acoustic embedded scattering eigenstates within the radiation continuum enabled by resonant metasurface pairs. At resonance, each metasurface strongly reflects the input wave, but as their surface resonances interfere with each other through coupling with a longitudinal resonance, an embedded eigenstate emerges. Through both theoretical and numerical analysis, we show the conditions for such an exotic resonant state to emerge and its implication for acoustic systems.

REDUCING THE CROSS-POLARIZATION PATTERN IN A DUAL-POLARIZED ANTENNA USING SPIRAL AND SPLIT RING RESONATORS

This paper introduces the design of a new dual polarization rectangular microstrip patch antenna based on metamaterial structures at X-band. The work focuses on two distinct configurations of a microstrip patch antenna utilizing metamaterials. Pairs of spiral ring resonators are loaded into a rectangular patch antenna system in the first design. The second strategy involves inserting a split ring resonator at the end of microstrip feed lines. The utilization of metamaterial structures in the microstrip antenna system compensates for the patch antenna's asymmetric current distribution of the flow, resulting in symmetrical current distribution. The simulation results display an import cross-polarization cross-polarization discrimination (XPD) and good port decoupling. The antenna system has various characteristics, including a basic structure and metamaterial inclusions that take up a small amount of space, making the suggested metamaterial inclusions more beneficial for dual-linear polarized patch antenna construction. These prototypes are suitable to work for polarimetric radars.

Displacement Sensors Based on the Phase of the Reflection Coefficient of a Split Ring Resonator-Loaded Transmission Line

In this article, novel displacement sensors using a microstrip loaded with a pair of split ring resonators (SRRs) are proposed. It is shown that the phase of the reflection coefficient from the loading SRRs can be used for displacement sensing. The article also proposes a differential version of the sensor that benefits from a higher sensitivity and reference zero, which is useful for alignment purposes. It is further shown that the concept of interferometry can be used to convert the output variable of the sensor from changes in the phase to variations in the amplitude of the reflected wave, which can be easily measured. To this end, the proposed single-ended or differential sensors are used along with a branch-line coupler. The proposed sensing mechanism is validated through electromagnetic (EM) simulation of the structures. The concept is further validated through the fabrication and measurement of a prototype.

Directionality between driven-dissipative resonators

The notion of nonreciprocity, in essence when going forwards is different from going backwards, emerges in all branches of physics from cosmology to electromagnetism. Intriguingly, the breakdown of reciprocity is typically associated with extraordinary phenomena, which may be readily capitalized on in the design of (for example) nontrivial electromagnetic devices when Lorentz reciprocity is broken. However, in order to enable the exploitation of nonreciprocal-like effects in the next generation of quantum technologies, basic quantum optical theories are required. Here we present a versatile model describing a pair of driven-dissipative quantum resonators, where the relative phase difference between the coherent and incoherent couplings induces an asymmetry. The interplay between the diverse dissipative landscape —which encompasses both intrinsic losses and dissipative couplings— and the coherent interactions leads to some remarkable consequences including highly directional (or even one-way) energy transport. Our work proffers the tantalizing prospect of observing dissipation-induced quantum directionality in areas like photonics or cavity magnonics (spin waves), which may aid the design of unconventional nanoscopic devices.

Spin-orbital Yu-Shiba-Rusinov states in single Kondo molecular magnet

Studies of single-spin objects are essential for designing emergent quantum states. We investigate a molecular magnet Tb2Pc3 interacting with a superconducting Pb(111) substrate, which hosts unprecedented Yu-Shiba-Rusinov (YSR) subgap states, dubbed spin-orbital YSR states. Upon adsorption of the molecule on Pb, the degeneracy of its lowest unoccupied molecular orbitals (LUMO) is lifted, and the lower LUMO forms a radical spin via charge transfer. This leads to Kondo screening and subgap states. Intriguingly, the YSR states display two pairs of resonances with clearly distinct behavior. The energy of the inner pair exhibits prominent inter and intra molecular variation, and it strongly depends on the tip height. The outer pair, however, shifts only slightly. As is unveiled through theoretical calculations, the two pairs of YSR states originate from the ligand spin and charge-fluctuating higher LUMO, coexisting in a single molecule, but only weakly coupled presumably due to different spatial distribution. Our work paves the way for understanding complex many-body excitations and constructing molecule-based topological superconductivity.

Design of a four‐way out‐of‐phase wideband filtering power divider with high selectively response

This paper proposes a four-way out-of-phase wideband filtering power divider (OWFPD). By introducing a multiport out-of-phase topology, and a pair of multimode U-shape slotline resonators, satisfactory wideband out-of-phase filtering power division responses can be easily achieved. Owing to the different standing wave distribution of the slotline, adjacent out ports can exhibit out-of-phase characteristic. In the meantime, decent port-to-port isolations are attained with the developed isolation network. Thoroughly theoretical theory and design procedure are provided to explore the operation and guide the multiway OWFPD design. For validation, one prototype is implemented. Results indicate that the new four-way OWFPD exhibits compact size, sharp roll-off, good in-band isolations as well as nice phase and magnitude imbalance.

Port isolation improvement of full‐duplex single‐patch antenna by loading full‐wave resonators

In this article, a pair of full-wave microstrip resonators is loaded at the nonradiative edges of the patch to improve port isolation of two-port copolarized single-patch antennas (SPAs) for full-duplex applications. First, the decoupling mechanism and its resulting radiation characteristics are exhaustively analyzed, which indicates that more similar radiation patterns and lower crosspolarization can be achieved based on the directly suppressing port coupling. Then, a transversal-section-like topology composed of an additional interference path and the SPA is proposed to realize this purpose. To clearly illustrate the operation principle in practical design, the phase shifts of both paths, that is, the interference paths from Port 1 to Port 2 via the patch and the full-wave resonators, are exhaustively investigated. Attributing to the realization of a stable 180° out of phase between the two paths, the resultant signal is highly and stably attenuated by the interfering signal, and the desired port isolation is satisfactorily attained by manipulating its amplitude readily. The measured results show a dramatic enhancement in isolation between the two ports from 4 to 55 dB with good impedance matching at the two ports. Most importantly, benefiting from the idea of direct port isolation, the radiation performance is hardly deteriorated, with a maximum gain of 8 dBi, beam squint angle of only 10°, and low crosspolarization in the upper half-space.

Nonperturbative structure in coupled axion sectors and implications for direct detection

Pairs of misalignment-produced axions with nearby masses can experience a nonlinear resonance that leads to enhanced direct and astrophysical signatures of axion dark matter. In much of the relevant parameter space, self-interactions cause axion fluctuations to become nonperturbative and to collapse in the early Universe. We investigate the observational consequences of such nonperturbative structure in this ``friendly axion'' scenario with $3+1$ dimensional simulations. Critically, we find that nonlinear dynamics work to equilibrate the abundance of the two axions, making it easier than previously expected to experimentally confirm the existence of a resonant pair. We also compute the gravitational wave emission from friendly axion dark matter; while the resulting stochastic background is likely undetectable for axion masses above $10^{-22} \, \text{eV}$, the polarization of the cosmic microwave background does constrain possible hyperlight, friendly subcomponents. Finally, we demonstrate that dense, self-interaction--bound oscillons formed during the period of strong nonlinearity are driven by the homogeneous axion background, enhancing their lifetime beyond the in-vacuum expectation.

Dual-Narrowband/Wideband Filters Using Modified Coaxial Cavities With Large Frequency Ratios

This article presents two types of dual-narrowband/ wideband filters using modified coaxial cavities with large frequency ratios. The dual-narrowband/ wideband filters mean two dual-band bandpass filters, one of which is a dual-band wideband filter, and the other is a dual-band narrowband filter. The proposed coaxial resonator in the dual-narrowband filter consists of a pair of disk-loaded coaxial stepped impedance resonator (DLCSIR), which provides a large frequency ratio. The frequency ratio of the first two resonant modes of the DLCSIR can be precisely controlled by adjusting the impedance ratios and dimensions of the loading disk. By contrast, the proposed coaxial resonator in the dual-wideband filter is a rectangular coaxial stepped impedance resonator (RCSIR), which has the merits of miniaturized size, large frequency ratio, and convenience for strong coupling. Finally, two second-order dual-narrowband/ wideband filters with large frequency ratios were designed, fabricated, and measured. The exhibited dual-passband performance of the two filters verifies the proposed concept.

Photo-enhanced O−, H− and Br− ion production in caesium sputter negative ion source—no evidence for resonant ion pair production

It has been proposed that the negative ion yield of a caesium sputter ion source could be enhanced by promoting neutral caesium atoms to electronically excited 7p states supporting resonant ion pair production. We have tested this hypothesis by illuminating the cathode of a caesium sputter ion source with an adjustable wavelength laser and measuring its effect on the extracted beam currents of O−, H− and Br− anions. The laser exposure causes the beam currents to increase but the effect is independent of the wavelength in the range of 440–460 nm, which leads us to conclude that there is no evidence for resonant ion pair production. The photon-induced beam current enhancement scales with the applied laser power and, depending on the ion source conditions, can more than double the extracted beam current. We present a qualitative explanation for the observed effect. The model, based on photoelectron emission and subsequent increase of the caesium sputtering rate, thus liberating negative ions from the cathode, is supported by the data demonstrating that the caesium sputter ion source can produce Br− beams without thermal surface ionization as a source of Cs+ ions, i.e. in external laser-driven mode without heating the surface ionizer.

Benchmarking di-Higgs production in various extended Higgs sector models

We present a comprehensive study on Higgs pair production in various archetypical extended Higgs sectors such as the real and the complex 2-Higgs-Doublet Model, the 2-Higgs-Doublet Model augmented by a real singlet field and the Next-to-Minimal Supersymmetric extension of the Standard Model. We take into account all relevant theoretical and experimental constraints, in particular the experimental limits on non-resonant and resonant Higgs pair production. We present the allowed cross sections for Standard Model (SM)-like Higgs pair production and the ranges of the SM-like Yukawa and trilinear Higgs self-coupling that are still compatible with the applied constraints. Furthermore, we give results for the pair production of a SM-like with a non-SM-like Higgs boson and for the production of a pair of non-SM-like Higgs bosons. We find that di-Higgs production in the models under investigation can exceed the SM rate substantially, not only in the non-resonance region but also due to resonant enhancement. We give several benchmarks with interesting features such as large cross sections, the possibility to test CP violation, Higgs-to-Higgs cascade decays or di-Higgs production beating single Higgs production. In all of our benchmark points, the next-to-leading order QCD corrections are included in the large top-mass limit. For these points, we found that, depending on the model and the Higgs pair final state, the corrections increase the leading order cross section by a factor of 1.79 to 2.24. We also discuss the relation between the description of Higgs pair production in an effective field theory approach and in the specific models investigated here.

Single-coil Design Approach for Dual-band Near-field Coupled Resonators

With the adoption of single coil approach, printed spiral resonator design strategy for near-field wireless energy transfer is presented. A pair of symmetrical resonators operating at high frequency band specifically 6.78 MHz and 13.56 MHz is designed. Simulated power transfer efficiency (PTE) of over 88% are obtained for both frequencies when coupled spiral resonators separated at a distance of 25 mm is integrated with hybrid compensation network topology. The variance of PTE between both frequencies is about 0.04.

Dual-Band Independent Permittivity Sensor Using Single-Port With a Pair of U-Shaped Structures for Solid Material Detection

This study proposes a single-port dual-band independent microwave sensor for detecting solid materials. The sensor structure consists of a pair U-shaped resonators connected by a power divider and a microstrip feed line with an impedance of 50 Ohms with two different sensing hotspots. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1^{\text {st}}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2^{\text {nd}}$ </tex-math></inline-formula> resonators operate at a frequency of 1.200 GHz and 2.100 GHz, respectively. The type of material under test (MUT) is a standard material with a size of 10 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times10$ </tex-math></inline-formula> mm (RO5880, RO4003C, and FR4). The proposed sensor had a very high accuracy compared with both of using permitivitty from datasheet and calibrated frequency from simulation for the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1^{\text {st}}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2^{\text {nd}}$ </tex-math></inline-formula> resonator, respectively. Moreover, the pair of the U-shaped resonators had independent performances and they did not affect each other when the MUT was loaded. Furthermore, it can also operate with single-port measurement, which is a more efficient resource. Finally, the proposed microwave sensor can be a promising solution for detecting different permittivity of solid materials independently with high accuracy for applications such as the food industry, material quality control, and biomedical.

Multiple Spoof Plasmonically Induced Transparency for Sensing Applications

We design a pair of resonators to realize multiple spoof plasmonically induced transparency (PIT) with high-Q group delays, which show potential in sensing applications. To reveal the mechanism of the multiple spoof PIT scheme, we deduce mathematical equations of a simplified model composed of multiple harmonic oscillators, and we further propose an equivalent-circuit model to analyze the metamaterials in an intuitive way. A prototype consisting of a broadband stub resonator and a spoof localized surface-plasmonic resonator is further fabricated to detect the complex permittivity of high-lossy liquids and solid samples in microwave bands. Experimental results show that the group-delay-based sensor can work well even when high-order modes are weakly excited, and the trade-off between sensitivity and properties of samples is discussed. The proposed double-resonator scheme with multiple spoof PIT is universal, and we design a metasurface working in terahertz bands to show that the concept can be widely used in various surface-sensing applications.

Resonance capture and long-term evolution of planets in binary star systems

Aims. The growing population of planets discovered in orbit around one stellar component of a binary star raises the question of the influence of the binary companion on the formation process of planetary systems. The aim of this work is to study the impact of a binary companion on the evolution of two-planet systems during both the Type-II migration phase and their long-term evolution after the dissipation of the protoplanetary disk. Methods. We used the symplectic integrator SyMBA, modified to include a wide binary companion. We also included the Type-II migration of giant planets during the protoplanetary disk phase with suitable eccentricity and inclination damping as well as the gravitational potential acting on the planets due to the disk and the nodal precession of the disk induced by the binary companion. We considered various inclinations, eccentricities, and separations of the binary companion. Results. Disk migration allows for the formation of planet pairs in mean-motion resonances despite the presence of the binary companion. When the binary separation is wide (1000 au), the timescale of the perturbations that it raises on the planets is longer than the disk’s lifetime and resonant pairs are routinely formed in the 2:1, 5:2, and 3:1 commensurabilities. Provided the planet-planet interaction timescale is smaller than the timescale of binary perturbations, these systems can remain in resonance long after the disk has dissipated. When the binary separation is smaller (250 au), only planets in the 2:1 resonance tend to remain in a resonant state and more chaotic evolutions are observed, as well as more ejections. After those ejections, the remaining planet can become eccentric due to the perturbations from the binary companion in addition, for strongly inclined binary companions, captures in the von Ziepel-Lidov-Kozai resonance can occur. Whereas in systems with two planets, this mechanism is quenched by planet-planet interactions. Our simulations reveal that the interplay between planet-disk, planet-planet, and planet-binary interactions can lead to the formation of resonant pairs of planets which remain stable over timescales much longer than the disk’s lifetime.