Array Of Resonators Research Articles

Topological localized modes in moiré lattices of bilayer elastic plates with resonators

We investigate the existence of higher order topological localized modes in moiré lattices of bilayer elastic plates. Each plate has a hexagonal array of discrete resonators and one of the plates is rotated at an angle (21.78∘) which results in a periodic moiré lattice with the smallest area. The two plates are then coupled by inter-layer springs at discrete locations where the top and bottom plate resonators coincide. Dispersion analysis using the plane wave expansion method reveals that a bandgap opens on adding the inter-layer springs. The corresponding topological index, namely fractional corner mode, for bands below the bandgap predicts the presence of corner localized modes in a finite structure. Numerical simulations of frequency response show localization at all corners, consistent with the theoretical predictions. The considered continuous elastic bilayered moiré structures opens opportunities for novel wave phenomena, with potential applications in tunable energy localization and vibration isolation.

Observation of Quasi-Invariant Photocarrier Lifetimes in PbS Nanocrystal Assemblies Coupled to Resonant and Nonresonant Arrays of Optical Antennas

Observation of Quasi-Invariant Photocarrier Lifetimes in PbS Nanocrystal Assemblies Coupled to Resonant and Nonresonant Arrays of Optical Antennas

Magnon-magnon coupling mediated by topological edge states

The topology of the photonic bath shows excellent potential to engineer the intriguing interaction properties between light and matter. Here, we study the dielectric resonator array with a zigzag geometry, an analogy of the Su-Schrieffer-Heeger model equipped with peculiar freedom to manipulate the nearest-neighbor coupling strength by the internal interaction. A staggered coupling strength of s-type pillar modes is experimentally achieved via the photonic spin-orbit coupling by employing the zigzag dielectric resonator chain. As a result, we observe that the robust edge states of the zigzag chains manifest themselves with linear polarization for an even number of dielectric resonators but elliptical polarization for an odd number. In addition, by coupling magnons to the topological waveguide, we observe resonant magnon–magnon–edge-state coupling, whose coupling strength is topologically protected. More broadly, our work shows that topological waveguide-QED systems may provide the potential for synthesis and study of many-body states with attractive long-range interaction. Published by the American Physical Society 2024

Double-order coupling bandgap design of metamaterial beams and broadband vibration reduction properties

<sec>Local-resonance bandgap and Bragg bandgap can coexist in a metamaterial beam, and their coupling effect can be used to realize ultra-wide bandgap, which has great potential applications in the field of wide-band vibration reduction. Previous studies usually considered the single-order coupling between the local-resonance bandgap and Bragg bandgap in metamaterial beams with a single array of local resonators, which can only achieve the single-order ultra-wide coupling bandgap and cannot meet the wide-band vibration reduction requirements of double/multiple target frequency bands. In this paper, metamaterial beams with double arrays of local resonators are considered, and the regulation design and analysis of double-order coupling of local-resonance and Bragg bandgaps are carried out based on an analytical model of bending wave dispersion relation. Moreover, the vibration reduction characteristics of the double-frequency-resonator metamaterial beams with double-order coupling bandgaps are studied by using spectral element method and the finite element method. The main conclusions are as follows.</sec><sec>1) A design method is proposed for realizing double-order coupling wide bandgap in a metamaterial beam with double arrays of local resonators. By using this method, the resonance frequencies of the local resonators can be quickly designed on conditions that host beam parameters, lattice constant and added mass ratio of the local resonators are given.</sec><sec>2) The double-order coupling bandgaps in a metamaterial beam carrying double arrays of local resonators are compared with the single-order coupling bandgaps in metamaterial beams with a single array of local resonators. It is found that through proper design, the total normalized width of the double-order coupling bandgap can be much broader than that of the single-order coupling bandgap, so the double-order coupling bandgap is more beneficial to wide-band vibration reduction.</sec><sec>3) It is found that for a given total added mass ratio of the double arrays of local resonators, it is necessary to optimize the mass distribution ratio of the double resonators to maximize the total normalized width of double-order coupling bandgap. An approximate formula for designing the optimal mass distribution ratio of the double resonators is further established.</sec><sec>4) The spectral element method is used to study the vibration reduction characteristics of the metamaterial beams carrying double arrays of local resonators designed based on double-order bandgap coupling. The accuracy of the spectral element method is verified by comparing with the finite element method. The results show that significant vibration reduction can be achieved in two wide frequency bands corresponding to the double-order coupling bandgaps. The influences of number of unit cells and resonator damping on the vibration reduction characteristics of the metamaterial beam are further analyzed. It is shown that the increase of number of unit cells can enhance the vibration reduction performance in the bandgap, and the increase of resonator damping can effectively broaden the vibration reduction frequency band.</sec>

Mass-spring model for acoustic metamaterials consisting of a compact linear periodic array of dead-end resonators.

This paper presents a mass-spring model to predict the normal incidence acoustic response of a metamaterial composed of a compact linear periodic array of dead-end resonators. The dead-end resonators considered are ring-shaped Helmholtz resonators. The model is based on a mass-spring analogy and considers the thermoviscous losses in the metamaterial following an effective fluid approach. A matrix equation of acoustic motion is derived for the finite case of N-periodic arrays. Under external excitation, its direct solution predicts the sound absorption coefficient and transmission loss. Under the homogeneous case, the solution of its associated eigenvalue problem predicts the acoustic eigenfrequencies and mode shapes. The dispersion relation is also solved to predict the beginning of the first stopband, and a low frequency approximation allows development of a formula to estimate the first eigenfrequency. The results show that the system with N degrees of freedom has three stopbands over the frequency range studied, with zero sound absorption and transmission. The model also helps to understand how the acoustic dissipation, at a given resonant frequency, is affected by the position of the acoustic velocity nodes (eigenmodes) in the geometry of the metamaterial. Prototypes are designed, manufactured, and tested in an impedance tube to validate the model.

Surface impedance and topologically protected interface modes in one-dimensional phononic crystals

When semi-infinite phononic crystals (PCs) are in contact, localized modes may exist at their boundary. The central question is generally to predict their existence and to determine their stability. With the rapid expansion of the field of topological insulators, powerful tools have been developed to address these questions. In particular, when applied to one-dimensional systems with mirror symmetry, the bulk-boundary correspondence claims that the existence of interface modes is given by a topological invariant computed from the bulk properties of the PC, which ensures strong stability properties. This one-dimensional bulk-boundary correspondence has been proven in various works. Recent attempts have exploited the notion of surface impedance, relying on analytical calculations of the transfer matrix. In the present work, the monotonic evolution of surface impedance with frequency is proven for all one-dimensional PCs with mirror symmetry. This result allows us to establish a stronger version of the bulk-boundary correspondence that guarantees not only the existence but also the uniqueness of a topologically protected interface state. This correspondence is extended to a larger class of one-dimensional models that include imperfect interfaces, array of resonators, or dispersive media. Numerical simulations are proposed to illustrate the theoretical findings.

Toward practical mass spectrometry with nanomechanical pillar resonators by surface acoustic wave transduction

Nanoelectromechanical systems (NEMS) have shown outstanding performance in the detection of small masses down to single proton sensitivity. To obtain a high enough throughput for application in practical mass spectrometry, NEMS resonators are arranged in two-dimensional (2D) arrays. However, all state-of-the-art electromechanical transduction methods rely on electrical lines placed close to the mechanical resonators, which drastically restricts the density of 2D resonator arrays. An exception is the transduction by surface acoustic waves (SAWs), which has so far only been shown for the transduction of single nanomechanical pillar resonators. Here, we demonstrate the transduction of pillar pairs by SAWs. The pillars have a diameter of 700 nm and show a mass responsivity of −588 ± 98 ng−1. The distances between the pillar pairs are 70 nm and 14.3 µm. SAW transduction enabled us to measure both pillars of each pair with electrical lines no closer than 300 µm, illustrating the potential of SAWs to transduce dense arrays of pillar resonators, a crucial step toward practical mass spectrometry with NEMS.

Maze-Based Scalable Wireless Power Transmission Experimental Arena for Freely Moving Small Animals Applications.

This paper presents an innovative T/Y-maze-based wireless power transmission (WPT) system designed to monitor spatial reference memory and learning behavior in freely moving rats. The system facilitates uninterrupted optical/electrical stimulation and neural recording experiments through the integration of wireless headstages or implants in T/Y maze setups. Utilizing an array of resonators covering the entire underneath of the mazes, the wireless platform ensures scalability with various configurations. The array is designed to ensure a natural localization mechanism to localize the Tx power toward the location of the Rx coil. The system is analyzed and modeled using ANSYS HFSS software to optimize design. The primary goal was to achieve uniform wireless power delivery throughout the mazes through a comparative study of different transmitter (Tx) array configurations, such as float, series, and parallel resonators. The calculated Specific Absorption Rate (SAR) in rat tissue model equals 1.7 W/kg at the power carrier frequency of 13.56 MHz. A prototype of the proposed maze-based WPT design, featuring 8 Tx resonators, a Tx coil and power amplifier, and a headstage power harvesting unit, is successfully implemented and its performance characterized for all three resonator configurations. The implemented T maze-based WPT system has a total length of 128 cm. In the overlapping Tx resonators configuration, a homogeneity of 94% is achieved for the measured power transfer efficiency at over 30%, while continuously delivering over 60 mW for series configuration.

DESIGN OF A SWITCHED BEAM ANTENNA SYSTEM USING A 4 × 4 BUTLER MATRIX FOR WIRELESS COMMUNICATION APPLICATIONS

Demand for quality service within the cellular network, which has many cells within the cluster, has certain requirements to satisfy the customer or subscriber at any cost. Hence, a reliable approach to provide quality service to the subscriber is needed, and in that attempt, a switched beam system is proposed, which is composed of a Butler matrix operating at 2 GHz for 5G wireless communication systems. The Butler matrix operates at 2 GHz, however, and has an overall bandwidth of 1.2 GHz, ranging from 1.8 GHz to 3 GHz. The beamforming operation is completed by incorporating an antenna array; typically for such applications a linear array with half lambda spacing is preferred. Here, the antenna array is made of a dielectric material, hence forming a dielectric resonator array operating at the same frequency as that of the Butler matrix. To complete the switched beam system, a radiofrequency source is chosen, typically USRP 2900 from National Instruments, to provide excitation to the Butler matrix throughout its operation. The simulation is carried out in Ansys HFSS and PCB Antenna Designer from MathWorks. This article gives the simulation as well as measured results of the Butler matrix and dielectric resonator antenna and draws a conclusion of the performance of the system based on simulated and measured results.

Selective Functionalization of Micromachined Quartz Resonator Arrays using Electrochemical Techniques for Biosensing Applications

Selective Functionalization of Micromachined Quartz Resonator Arrays using Electrochemical Techniques for Biosensing Applications

Harnessing Coupled Resonances in Dielectric Resonator Array for Strong Evanescent Fields

Harnessing Coupled Resonances in Dielectric Resonator Array for Strong Evanescent Fields

Cutting Corners to Suppress High-Order Modes in Mie Resonator Arrays

Cutting Corners to Suppress High-Order Modes in Mie Resonator Arrays

Low-loss plasmonic resonance using surface Bloch waves in photoplasmonic metamaterials

We present a method for the suppression of the radiative loss of plasmonic resonant modes by efficiently coupling them with the nonradiative Bloch surface waves in photoplasmonic metamaterials, comprised of a 2D array of plasmonic resonators deposited on the low-index termination layer of a 1D photonic crystal. The number of photonic crystal bilayers plays a crucial role in the plasmonic radiative loss, with Q-values increasing with incrementing photonic crystal bilayers reaching values of ∼580 in the UV-Vis regime. We also show that the fundamental plasmonic mode of the metamaterial split into different energy levels corresponding to surface Bloch waves associated with each bilayer of the photonic crystal.

Robust multi-mode rainbow trapping with ultra-high-Q Fano resonances.

We present a groundbreaking and versatile approach to multi-mode rainbow trapping in photonic crystal waveguides (PCWs), overcoming long-standing limitations in photonic device design. Our innovative semi-bilayer PC design, formed by stacking two PCs, enables the realization of new photonic modes that were previously inaccessible, leading to enhanced device flexibility, improved performance, and increased resilience to defects and imperfections. By meticulously engineering a chirped PC within the PCW, we achieve multi-mode light trapping at distinct positions for different frequencies along the waveguide, effectively creating a rainbow of light. This study paves the way for efficient and robust trapping and demultiplexing of multiple wavelengths, opening up new avenues for on-chip nanophotonic applications. Moreover, the realization of ultra-high-quality (Q) factor Fano resonances within the waveguide cavity unveils unprecedented possibilities for designing on-chip nanophotonic devices. The diverse array of Fano resonances holds immense potentials for developing novel optical filters, switches, and lasers with exceptionally low thresholds. Our proposed structure offers a more compact, efficient, and robust solution for multi-wavelength photonic device applications.

High-efficiency electromagnetic energy harvesting using double-elliptical metasurface resonators.

This study introduces a metasurface (MS) based electrically small resonator for ambient electromagnetic (EM) energy harvesting. It is an array of novel resonators comprising double-elliptical cylinders. The harvester's input impedance is designed to match free space, allowing incident EM power to be efficiently absorbed and then maximally channelled to a single load through optimally positioned vias. Unlike the previous research works where each array resonator was connected to a single load, in this work, the received power by all array resonators is channelled to a single load maximizing the power efficiency. The performance of the MS unit cell, when treated as an infinite structure, is examined concerning its absorption and harvesting efficiency. The numerical results demonstrate that the MS unit cell can absorb EM power, with near-perfect absorption of 90% in the frequency range of 5.14 GHz to 5.5 GHz under normal incidence and with a fractional bandwidth of 21%. The MS unit cell also achieves higher harvesting efficiency at various incident angles up to 60o. The design and analysis of an array of 4x4 double elliptical cylinder MS resonators integrated with a corporate feed network are also presented. The corporate feed network connects all the array elements to a single load, maximizing harvesting efficiency. The simulation and measurement results reveal an overall radiation to AC efficiency of about 90%, making it a prime candidate for energy harvesting applications.

On enhancing the noise-reduction performance of the acoustic lined duct utilizing the phase-modulating metasurface

This work proposes a noise-reduction structure that integrates phase-modulating metasurface (PMM) with acoustic liners (ALs) to enhance the narrow band absorption performance of a duct with relatively small length-diameter ratio. The PMM manipulates the wavefront by introducing different transmission phase shifts based on an array of Helmholtz resonators, so that the spinning wave within the duct can be generated. Compared with the plane wave, the generated spinning wave has a lower group velocity, which results in a greater traveling distance over the ALs in the duct. The optimization design is performed to determine the final structural parameters of the PMM, which is based on the predictions of the amplitude and phase shift of the acoustic wave at the outlet of the PMM using the theory of passive phased array. With the manipulation of the PMM, the incident plane wave is modulated into a spinning wave, and then enters into the acoustic liner duct (ALD), whose structural parameters are optimized by maximizing the transmission loss using the mode-matching technique. Finally, the noise-reduction performance of this combined structure is evaluated by numerical simulations in the presence of grazing flow. The results demonstrate that, compared with the traditional ALD, the proposed structure exhibits a significant increase in transmission loss within the considered frequency band, especially near the peak frequency of the narrow band noise.

Investigation of a new magnetorheological elastomer metamaterial plate with continuous programmable properties for vibration manipulation

Metamaterial plates have attracted considerable attention due to their unprecedented elastic wave manipulation abilities. Currently, the band gap and other properties of traditional metamaterial plates are fixed, and the material parameters of most metamaterials cannot be dynamically and continuously adjusted. To address this issue, a two-dimensional (2D) magnetorheological elastomer (MRE) programmable metamaterial plate (MREPMP) with local resonance was proposed. The proposed MREPMP was composed of a thin steel plate and a periodic array of resonators, consisting of MREs and electromagnetic mass blocks. It not only has a compact structural design, but also enables real-time vibration control and programming wave manipulation by altering the amplitude of the current. The dispersion relation of the proposed MREPMP was theoretically calculated based on the plane wave expansion (PWE) method and the simulated transmissibility was numerically calculated using the finite element method in COMSOL. Subsequently, a prototype of the MREPMP was fabricated, and vibration tests were conducted to assess its programmable vibration manipulation functionalities. Two different types of defect paths were used as excitations and the corresponding real-time vibration manipulation performance was analyzed. The simulation results agree with the experimental results, showing that the MREPMP can dynamically tune the band gap and activate different waveguides through continuous online programming. This paper opens up a new idea for tunable manipulation of wave propagation.

Chipless RFID Tag Implementation and Machine-Learning Workflow for Robust Identification

In this work, we describe a complete step-by-step workflow to apply machine-learning (ML) classification for chipless radio-frequency identification (RFID) tag identification, covering: 1) the tag implementation criteria for circular ring resonator (CRR) and square ring resonator (SRR) arrays for ML interoperability; 2) the data collection procedure to get a sufficiently representative dataset of real measurements; 3) the ML techniques to visualize the data and reduce its dimensionality; 4) the evaluation of the ML classifier to ensure high-accuracy predictions on new measurements; and 5) a thresholding scheme to increase the certainty of the predictions. The differences in the tags’ frequency responses are maximized by optimizing the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Hamming distance</i> between the tag identifiers (IDs) and by controlling each resonator array’s radar cross section (RCS) level. We show that the proposed workflow achieves perfect accuracy for the identification of four tags at a fixed distance of 160 cm. We also evaluate the performance of the proposed workflow to identify up to 16 tags within a flexible range (up to 140 cm), showcasing the tradeoff between the number of tags that can be correctly classified based on the reading range.

A Low-Noise Piezoelectric MEMS Oscillator Based on a Flexural Mode Membrane Resonator Array Toward In-Air Resonant Sensors

A Low-Noise Piezoelectric MEMS Oscillator Based on a Flexural Mode Membrane Resonator Array Toward In-Air Resonant Sensors

An acoustic metasurface by applying planar periodic arrays of resonators with a multiple folded long neck for broadband sound absorption

An acoustic metasurface gives a broadband sound absorption by a planar periodic array combining small resonant modules tuned at different frequencies. The resonant module is often applied by a Helmholtz resonator, a membrane backed by an airtight cavity and a quarter wavelength closed tube, which have equivalent small area to a fraction of the wavelength. The author has studied the sound absorption of resonators by applying a multiple folded long neck and an airtight cavity for a thin sound-absorbing structure with high sound absorption at low frequencies below 100 Hz. In this paper, the author prototypes an acoustic metasurface by planar periodic array of Helmholtz resonators at various resonant frequency tuned by this neck and cavity of the resonator as a unit cell, and discusses the sound absorption characteristics. The prototyped acoustic metasurface gives a 40 % - 70 % sound absorption from 125 Hz to 250 Hz when it is combined with a 6.4 mm thickness of top plate including a 24 mm - 96 mm length of the multiple folded long neck and a 43.2 mm depth of the airtight cavity. And, more broadband sound absorption will be discussed by a theoretical analysis.