Conventional Resonator Research Articles

Design of balanced UWB BPF based on quint‐mode slotline resonator

In this paper, a quint-mode slotline resonator (QMSR) is analyzed and designed. The proposed resonator has similar performances to those of the conventional microstrip multimode resonator, while it is located at the bottom ground layer. To the best of our knowledge, this is the first time that QMSR is proposed. By properly adjusting the dimensions of the proposed QMSR, quasi-independent control of the five resonant frequencies is realized, thereby an ultrawideband (UWB) differential-mode (DM) transmission passband can be obtained. By employing balanced microstrip/slotline transition structure, a high and wideband common-mode (CM) suppression can also be realized, which is independent of the DM responses. Thereby, only the DM performances need to be considered, which simplify the design procedure greatly. In addition, one notched band is achieved to suppress the special electromagnetic interference. To validate the design concept, one prototype circuit of the proposed balanced UWB bandpass filter is implemented following the given design procedure. Good agreement between the measurement and simulation results can be observed.

Application of the meta-substrates for power amplification in rotary piezoelectric energy harvesting systems: Design, fabrication and testing

In this paper we numerically and experimentally investigate a new proposal of utilizing the auxetic meta-structure concepts to enhance the efficiency of piezoelectric energy harvesters in rotating systems. The proposed energy harvester is designed to be installed on the freight train axel to provide necessary power for the self-powered sensors. The harvester is a resonator consists of a cantilever beam with a tip mass and a piezoelectric patch mounted on its latticed substrate. Three various auxetic patterns are suggested and implemented on the base of the cantilever in order to enhance the harvested powers. The efficiency enhancement of the suggested concepts is compared with a conventional plain resonator. In order to optimize the geometrical parameters of the auxetic patterns and investigate the efficiency of various resonator’s output power, the finite element modeling (FEM) is employed. Maximum output powers according to the optimum electrical resistance and resonance frequency are achieved. Also, the effects of different PZT types on the extracted energy are taken into investigation. Two different substrate materials (aluminum and steel) are used in the fabrication of resonators. The​ numerical models are validated by experimental results in the rotating speed at the range of 6–7 Hz, which is tuned to the operational rotational frequency of the freight train axles. It is shown that for Auxetic-I, Auxetic-II, and Auxetic-III, the magnification factors are 3.28, 2.5, and 2.14 are achieved for the aluminum substrate. These factors are 3.0, 2.6, and 2.3 for the steel resonator, respectively. The experimental results show that the auxetic resonators are able to considerably enhance the efficiency of rotary energy harvesting systems.

Compact and high Q-factor multimode racetrack ring resonator based on transformation optics.

The ring resonator is a versatile and functional component in the silicon-based integrated optical circuit. Most of the previously reported ring resonators work in the single-mode case. With the rapid development of mode division multiplexing technology, a multimode ring resonator (MMRR) has been proposed and the usage beyond the limit of a conventional single mode ring resonator has been explored. However, the reported MMRRs are either large in size or low in quality factor. In this paper, we designed a compact silicon MMRR with a small bending radius of 15µm, in which the three lowest TE modes all have high Q-factors. For suppressing the mode loss and inter-mode crosstalk in MMRR, a multimode waveguide bend (MWB) with mode adiabatic evolution was designed based on transformation optics and waveguide shape optimization. The independent excitation of each order mode of the MMRR is realized by using bending directional coupler and asymmetric directional coupler. We successfully fabricated the device on a silicon-on-insulator (SOI) platform using simple one-step lithography. The measured loaded Q-factors of the three lowest TE modes are 5.9 × 104, 4.5 × 104, and 4.7 × 104, respectively.

Equal/unequal half mode substrate integrated waveguide filtering power dividers using an ultra-compact metamaterial unit-cell

Abstract In this paper, a novel ultra-compact metamaterial unit-cell is introduced. The proposed unit-cell consists of one modified rings which has been designed based on the fractal technique and meander technique. These techniques are used to reduce the physical size of the conventional complementary split ring resonators (CSRRs). In the proposed metamaterial unit-cell which is called the fractal/meander CSRR (FMCSRR), the slot lines in the conventional CSRRs are replaced by the fractal and meander slots, simultaneously. The FMCSRR unit-cell is a planar metamaterial element which exhibits negative permittivity and is considered as electric dipole when excited by an axial electric field. Thus, the FMCSRR unit-cell is modeled as a shunt resonator tank. Therefore, by using the proposed FMCSRR configuration, all of the interior space of the ring has been used and the slot lines have been increased. Consequently, the higher inductance has been achieved and the resonance frequency of the proposed FMCSRR unit-cell becomes lower compared with the conventional CSRR. That’s mean the electrical size of the introduced unit-cell FMCSRR unit-cell is smaller than the conventional CSRR with the same physical sizes. A microstrip notch band filter, a microstrip band-pass filter, a half mode substrate integrated waveguide (HMSIW) band-pass filter and three HMSIW filtering power dividers (FPDs) with different power division ratios of 1:1, 1:4, and 1:8 have been designed to illustrate the ability of the proposed FMCSRR unit-cell in the size reduction. All of the designed devices operated at 2.4 GHz which are suitable for WLAN applications. For verification the performance of the utilized techniques in miniaturization of the dimension, the designed equal/unequal HMSIW FPDs have been fabricated and tested. A reasonable agreement between simulated and measured results has been achieved. The results confirmation that a miniaturization about 79% has been obtained. The total size of the proposed HMSIW FPDs are about 0.09λ g × 0.09λ g. The proposed HMSIW FPDs have many advantages in terms of compact size, low insertion loss, high selectivity, easy integration with the other planar circuits, and controllable bandwidth.

The Development of 170 GHz, 1 MW Gyrotron for Fusion Application

This paper presents the overall conceptual design of a 170 GHz, 1 MW gyrotron for plasma heating applications in thermonuclear fusion reactors. The operating mode is carefully selected with consideration of mode competition. The TE25,10 mode is determined as the operating mode in the present study. A weakly tapered conventional resonator is used for the study of the RF behavior, and multimode calculations are carried out for power and efficiencies. The optimized structure of the beam tunnel can further attenuate low-frequency oscillation. The design studies of a triode-type magnetic injection gun, quasi-optical mode converter, and single-disc sapphire window are also described. In addition, novel cold test methods which can effectively validate assembles are designed. In 2021, a prototype gyrotron was fabricated to validate the electronic–optic system and RF system. The current results obtained support an output power of 210 kW and efficiency of 15.9% through an initial low-power experiment. On the basis of the optimized design, an industrial prototype gyrotron is under fabrication as the heating source for the thermonuclear experimental reactor.

Triple Mass Resonator for Electrostatic Quality Factor Tuning

In this paper, a triple mass resonator (TMR) with a high capability to independently tune both resonant frequency and quality factor (Q-factor) is reported. An additive oscillating structure is designed into a conventional dual-mass resonator to control the modal shape. The theoretical studies revealed that the amplitude ratio between the outer masses, which mainly determine the Q-factor through the anchor loss, is sensitive to both suspension and inner springs because of mode coupling, while the resonant frequency is only sensitive to the suspension spring. Through this mechanism, the quality factor related to the anchor loss, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q_{\mathrm {Anchor}}$ </tex-math></inline-formula> , can be adjusted by electrostatic tuning of the inner spring, while the resonant frequency keeps almost constant. On the other hand, the eigenfrequency could be significantly tuned by the electrostatic tuning of the suspension spring. The experimental results showed the Q-factor could be tuned as large as 19% by a DC bias of 15 V at the inner electrode, while the resonant frequency change was only as small as 162 ppm. In contrast, when the DC bias was applied to soften the suspension stiffness, the resonant frequency could be tuned as high as 7023 ppm with Q-factor change of 16%. [2021-0167]

Leakage Effect on the Transmission Properties of a Duct Loaded with a Helmholtz Resonator

The characteristics of transmitted acoustic field have important significance to the leakage detection and the acoustic metasurface technology. When the additional leak holes are present, the conventional single neck Helmholtz resonator will naturally become the one with multiple necks. Based on such a background, in this paper, the effects of leakages on the transmission properties of a Duct Helmholtz Resonator (DHR) device is investigated both analytically and numerically. A set of closed-form formulas are derived to analytically predict the transmission spectra of the DHR device with leakages. The theoretical results are compared with COMSOL predictions. The simulation results show that the number and width of leak holes have significant influences on the amplitude, phase shift of the transmitted wave, and resonance frequency of the DHR system.

Elastic strain engineered nanomechanical GaN resonators with thermoelastic dissipation dilution up to 600 K

Conventionally, mechanical resonators exhibit evident degradation in quality factor and large frequency fluctuation at elevated temperatures above room temperature. Here, we show that the quality factor of up to 105 of a highly stressed GaN on Si nanomechanical resonators experiences little change as temperature increasing to 600 K and the temperature coefficient of the resonance frequency (TCF) is as low as several ppm/K, several times lower than those of the conventional GaN mechanical resonators. The high quality factor and low TCF at high temperatures are attributed to the high stress and the geometrical nonlinearity of dynamical strain in the GaN resonator, where the dissipation caused by the change of the material properties with the increasing temperature is compensated by the increased stiffness. This observation violates the universality of thermal energy dissipation in mechanical resonators. The results provide a universal strategy for engineering nanomechanical resonators with ultrahigh sensitivity and ultralow noise.

Figure of Merit Enhancement of Laterally Vibrating RF-MEMS Resonators via Energy-Preserving Addendum Frame.

This paper examines a new technique to improve the figure of merit of laterally vibrating RF-MEMS resonators through an energy-preserving suspended addendum frame structure using finite element analysis. The proposed suspended addendum frame on the sides of the resonant plate helps as a mechanical vibration isolator from the supporting substrate. This enables the resonator to have a low acoustic energy loss, resulting in a higher quality factor. The simulated attenuation characteristics of the suspended addendum frame are up to an order of magnitude larger than those achieved with the conventional structure. Even though the deployed technique does not have a significant impact on increasing the effective electromechanical coupling coefficient, due to a gigantic improvement in the unloaded quality factor, from 4106 to 51,136, the resonator with the suspended frame achieved an 11-folds improvement in the figure of merit compared to that of the conventional resonator. Moreover, the insertion loss was improved from 5 dB down to a value as low as 0.7 dB. Furthermore, a method of suppressing spurious mode is demonstrated to remove the one incurred by the reflected waves due to the proposed energy-preserving structure.

Research and design of broadband muffler based on second-order Helmholtz resonators

Noise is always a serious factor affecting people's quality of life. The most common sound-absorbing materials are porous materials, which work based on the principle that sound waves entering into the pores inside the material are subjected to air friction and viscous resistance, thus converting sound energy into heat. Porous materials have excellent performance of absorbing medium-frequency and high-frequency sound , but they are required to be thick enough to control the low-frequency sound waves with large wavelengths, which limits the application of porous materials in low-frequency noise control. In recent years, acoustic artificial structures have become a research hotspot, which can realize exotic effective acoustic parameters based on periodical structure or local resonance. Acoustic artificial structure provides a new material basis for noise control, in which Helmholtz resonator plays an important role because of its simple geometry. In this study, a broadband muffler is designed based on the second-order neck embedded Helmholtz resonator. In order to achieve low-frequency and broadband sound insulation with a limited number of units and structure length, the second-order resonator is chosen as a basic structure unit, which has a stronger low-frequency noise reduction capability and has one high-frequency transmission loss peak more than a conventional Helmholtz resonator. The acoustic characteristics and insulation performance of second-order resonators are analyzed through theoretical calculation, simulation calculation and experimental test. Then, based on the theoretical model and empirical rules, a broadband muffler composed of nine second-order resonators is designed by carefully adjusting the geometry parameters of each resonator. The three-dimensional printed resonators are installed on the side wall of a square standing wave tube for experimental measurement. In the experiment, the transmission loss curve of the muffler is measured by the two-load method. The result shows that the designed muffler has good sound insulation performances in a frequency range of 267–927 Hz, with the whole transmission loss above 20 dB and the maximum sound insulation up to 60 dB. The experimental result is consistent with the calculation result and simulation result. The muffler has simple structure and high practicability, which will have a wide application prospect in noise control engineering.

Comparison of crossed-Porro prism resonator design with conventional mirror resonator design in a Ho3+:YAG laser

Comparison of crossed-Porro prism resonator design with conventional mirror resonator design in a Ho³⁺:YAG laser

Compact dual-mode microstrip bandpass filter based on slotted square patch resonator

PurposeThe purpose of this paper is to present the design of a compact microstrip bandpass filter (BPF) in dual-mode configuration loaded with cross-loop and square ring slots on a square patch resonator for C-band applications.Design/methodology/approachIn the proposed design, the dual-mode response for the filter is realized with two transmission zeros (TZs) by the insertion of a perturbation element at the diagonal corner of the square patch resonator with orthogonal feed lines. Such TZs at the edges of the passband result in better selectivity for the proposed BPF. Moreover, the cross-loop and square ring slots are etched on a square patch resonator to obtain a miniaturized BPF.FindingsThe proposed dual-mode microstrip filter fabricated in RT/duroid 6010 substrate using PCB technology has a measured minimum insertion loss of 1.8 dB and return loss better than 24.5 dB with a fractional bandwidth (FBW) of 6.9%. A compact size of 7.35 × 7.35 mm2 is achieved for the slotted patch resonator-based dual-mode BPF at the center frequency of 4.76 GHz. As compared with the conventional square patch resonator, a size reduction of 61% is achieved with the proposed slotted design. The feasibility of the filter design is confirmed by the good agreement between the measured and simulated responses. The performance of the proposed filter structure is compared with other dual-mode filter works.Originality/valueIn the proposed work, a compact dual-mode BPF is reported with slotted structures. The conventional square patch resonator is deployed with cross-loop and square ring slots to design a dual-mode filter with a square perturbation element at its diagonal corner. The proposed filter exhibits compact size and favorable performance compared to other dual-mode filter works reported in literature. The aforementioned design of the dual-mode BPF at 4.76 GHz is suitable for applications in the lower part of the C-band.

Design of low phase noise K‐band VCO using high quality factor resonator in 0.18 μm CMOS technology

A novel resonator to improve the phase noise of a Voltage-Controlled Oscillator (VCO) utilizing double series resonances or two attenuation zeros to improve the susceptance slope parameter of the resonator circuit is proposed, and its effectiveness is demonstrated by designing a low phase noise K-band VCO. The first series resonance is created by an additional inductor (L) in series to the capacitor (C) in the parallel branch of a conventional LC-tank circuit, and the second one is realized by an additional capacitor in series to the whole resonator circuit. The additional L is realized by defected ground structures (DGS) so that there is no additional burden in the chip size. The proposed resonator is fabricated in 0.18 μm CMOS technology and has active quality factor of 101 and a compact size of 0.009 mm2 (0.00046 λ2). The measured return loss |S11| and insertion loss |S21| of the fabricated prototype resonator are 2.8 and 11 dB, respectively, at a center frequency of 37 GHz with 8 GHz of bandwidth. The resulting active quality (QK-) factor of the proposed resonator is enhanced significantly that, in returns, improves the phase noise. The design is implemented in 0.18 μm CMOS technology, and the post-layout simulation shows that VCO has a tuning range of 3.8% and phase noise of −114.4 dBc/Hz @1 MHz offset at 19.5 GHz oscillation. The VCO consumes 2.96 mW power resulting in a Figure of Merit (FoM) of −195.5 dB. The proposed resonators improve the VCO FoM by more than 5.5 dB compared to conventional LC resonator.

An Electrically Controlled Pattern- and Polarization-Reconfigurable Cylindrical Dielectric Resonator Antenna

A pattern- and polarization-reconfigurable dielectric resonator antenna (DRA) is presented. It deploys a conventional cylindrical dielectric resonator (DR) with a new switchable feeding network. The feeding network has four slots that are etched in the ground. By tuning the phase distributions in these slots, three DR modes (the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01δ</sub> and two degenerated HEM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">113</sub> modes) are excited. The former has an omnidirectional radiation pattern, whereas the latter two have boresight patterns with orthogonal polarizations ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> - and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> -polarization). By tuning the height-to-radius ratio, these modes can be designed to operate at the same frequency, thus enabling both the pattern and polarization reconfigurability. A prototype of the reconfigurable DRA working in 2.4 GHz is fabricated and measured to verify ideas. Reasonable agreement between measurements and simulations is obtained. Our design provides both pattern and polarization reconfigurability, with good efficiency in the band of interest.

Flexural wave propagation in locally-resonant beams with uncoupled/coupled bending-torsion beam-like resonators

A theoretical framework is presented to compute the dispersive properties of a locally-resonant Euler–Bernoulli beam hosting a periodic array of beam-like resonators, the bending-torsion response of which may be either uncoupled or coupled depending on the cross-section geometry. It is shown that, in the frequency domain, the reaction of every beam-like resonator can be expressed in an exact analytical form depending only on deflection and rotation of the host beam at the connection points. In this way, the beam-like resonators can be substituted by equivalent fictitious external supports with frequency dependent stiffness. On this basis: (a) band gaps of the infinite locally-resonant beam are easily computed employing a transfer matrix approach; (b) the frequency response, as well as the transmittance of the finite locally-resonant beam, are computed in closed analytical forms extending an efficient formulation recently proposed by the authors, based on generalized functions. In addition to presenting the novel theoretical framework, the main purpose of the paper is promoting coupled bending-torsion beam-like resonators as a novel concept for locally-resonant structures, which may prove even more efficient than conventional uncoupled bending-torsion beam-like resonators. Indeed, it is shown the former offer more and better opportunities to open band gaps, taking advantage of the inherent coupling between bending and torsional vibrations.

GeSnOI mid-infrared laser technology

GeSn alloys are promising materials for CMOS-compatible mid-infrared lasers manufacturing. Indeed, Sn alloying and tensile strain can transform them into direct bandgap semiconductors. This growing laser technology however suffers from a number of limitations, such as poor optical confinement, lack of strain, thermal, and defects management, all of which are poorly discussed in the literature. Herein, a specific GeSn-on-insulator (GeSnOI) stack using stressor layers as dielectric optical claddings is demonstrated to be suitable for a monolithically integration of planar Group-IV semiconductor lasers on a versatile photonic platform for the near- and mid-infrared spectral range. Microdisk-shape resonators on mesa structures were fabricated from GeSnOI, after bonding a Ge0.9Sn0.1 alloy layer grown on a Ge strain-relaxed-buffer, itself on a Si(001) substrate. The GeSnOI microdisk mesas exhibited significantly improved optical gain as compared to that of conventional suspended microdisk resonators formed from the as-grown layer. We further show enhanced vertical out-coupling of the disk whispering gallery mode in-plane radiation, with up to 30% vertical out-coupling efficiency. As a result, the GeSnOI approach can be a valuable asset in the development of silicon-based mid-infrared photonics that combine integrated sources in a photonic platform with complex lightwave engineering.

Möbius Strip Microlasers: A Testbed for Non-Euclidean Photonics.

We report on experiments with Möbius strip microlasers, which were fabricated with high optical quality by direct laser writing. A Möbius strip, i.e., a band with a half twist, exhibits the fascinating property that it has a single nonorientable surface and a single boundary. We provide evidence that, in contrast to conventional ring or disk resonators, a Möbius strip cavity cannot sustain whispering gallery modes (WGM). Comparison between experiments and 3D finite difference time domain (FDTD) simulations reveals that the resonances are localized on periodic geodesics.

Compact eighth‐mode ridged substrate integrated waveguide filter

In this letter, a novel eighth-mode ridged substrate integrated waveguide (EMRSIW) is proposed by bisecting the RSIW resonator along the virtual magnetic walls. The EMRSIW shows a size of nearly one-eighth of a conventional RSIW resonator and a significant size reduction compared to the conventional eighth-mode SIW resonator. A prototype of a third-order bandpass filter with transmission zeros has been designed and tested.

Compact Quadruple-Mode Wideband Bandpass Filter Using L-Shaped Feed-Line in a Single Cavity

This letter presents a novel quadruple-mode cavity wideband bandpass filter (BPF). Unlike the conventional coaxial cavity resonator, the proposed cavity resonator is made up of two symmetrical conductive posts in a cylindrical cavity, while four resonant modes of the cavity resonator are classified as TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> mode, TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode, and a pair of TE degenerate modes (TE+ mode and TE− mode). All of the four modes are excited by a pair of L-shaped feed-lines. In addition, the four resonant modes are employed to constitute the passband of wideband BPF with a fractional bandwidth (FBW) of 45% at the central frequency of 2.2 GHz. Finally, the proposed filter is designed and fabricated. Good in-band filtering performance, wide upper stopband, and compact size are realized.

Design and realization of high-quality multiplet independent resonance modes in a plasmonic waveguide structure

Multiplet independent resonance modes can be used to control light–matter interactions beyond the capability of conventional optical resonators. Here we present the design and fabrication of multiplexed gratings in a plasmonic waveguide structure to realize multiplet independent resonance modes. Based on the optimally chosen, low-loss plasmonic TM1 waveguiding mode, the multiplet resonance modes demonstrate relatively high-quality factors, field enhancements, overlapping resonance fields, and identical polarization states, advantageous to resonant control and enhancement of light–matter interactions. By adjusting structure parameters of the constitutive gratings, the respective resonance positions and their resonance intensities can be independently adjusted. Experimentally, the plasmonic structures with multiplexed gratings are fabricated, based on multi-exposure holographic lithography processes, which demonstrate arbitrarily adjustable doublet or triplet resonance modes.