Multimodal Resonance Research Articles

Locally resonant metamaterials with multimodal resonators for sound insulation improvement

Locally resonant metamaterials are used to increase the sound insulation of a host structure, by introducing bandgaps for wave propagation. While most solutions employ periodic layouts with translational resonators, this work investigates the potential of rotational and multimodal resonators. A comprehensive analytical model of sound insulation, based on dynamic effective mass density, is first presented. It is then demonstrated how multimodal locally resonant metamaterials can suppress the broad coincidence dip in the diffuse transmission loss of orthotropic host plates, and the geometry of two realizable multimodal resonators is optimized to maximize broadband sound insulation.

Compact multi-mode silicon-nitride micro-ring resonator with low loss

Compact multi-mode silicon-nitride micro-ring resonator with low loss

Wideband signal combining circuit based on multichannel different‐/same‐frequency power combiner

AbstractA wideband signal combining circuit with continuous bandwidth based on multichannel different‐/same‐frequency power combiner is presented. Two‐way signals with the same frequency can be combined to a higher power signal. Two‐way signals with different frequencies can be combined into a broadband signal. A stepped impedance resonator (SIR) is used as a multimode resonator. The wider bandwidth is got by SIR. And the selectivity of the two filtering channels is improved by the introduction of SIR stubs, which generate four transmission zeros on both sides of the passbands. The high 3‐dB point of the low‐frequency channel overlaps with the low 3‐dB point of the high‐frequency channel. Therefore, the output passband is continuous. The measured frequency ranges of two channels are 1.34–2.21 GHz/2.21‐2.87 GHz, respectively, and from 1.46 to 2.74 GHz, the input reflection coefficient is such that the return loss is higher than 15.5 dB. The insertion loss of the two channels is 0.71/1.18 dB, and the measured isolation is higher than 15.4 dB. The measured bandwidth of the combining signal is 1.5 GHz (1.34–2.84 GHz).

Dual UWB bandpass filter with highly band-to-band rejection using stepped impedance stub-loaded resonators for WBAN health-care applications

Abstract With the rapid development of communication technology, the researches of multi-band filtering circuits have become more and more important. Multimode resonator (MMR) is one of the vital methods to provide multi-resonant modes within a single design. In this paper, a dual-band ultra-wideband bandpass filter (UWB-BPF) using stepped impedance stub-loaded resonators (SI-SLR) is presented. The main advantage of using SI-SLR is to have better performance with multimode behavior and more parameters to control resonant modes. SI-SLR combines the advantages of SIR and SLR structures, which gives a compact, high-performance multiband filter. The proposed filter design has compact size, sharp and flat response with low insertion loss (IL), low return loss (RL), and high band-to-band rejection. The filter is designed for UWB communication in wireless body area networks and fabricated on Arlon substrate with relative permittivity ${\varepsilon_{\textrm{r}}} = 3.25$ , thickness $0.8\;{\textrm{mm}}$ . The resulted dual-bands are centered at $4{\textrm{ GHz}}$ and $8.3{\textrm{ GHz}}$ with fractional bandwidths $37{\textrm{% }}$ and $48{\textrm{%}}$ . The simulation was carried out using CST Microwave Studio. The filter provides good passband performances, with IL 0.49 dB and 0.31 dB at the center frequency of lower and higher bands, respectively. The band-to-band 40 dB rejection is realized by adding circular spiral at the input/output of the filter.

Multimode resonance transition to collapsed snaking in normal dispersive Kerr cavities: bright versus dark solitons.

We study the dynamics of Kerr cavity solitons in the normal dispersion regime in the presence of an intracavity phase modulation. The associated parabolic potential introduces multimode resonances, which promote the formation of high-order bright solitons. By gradually reducing the potential strength, bright solitons undergo a transition into dark solitons. We describe this process as a shift from a multimode resonance to a collapsed snaking bifurcation structure. This work offers a comprehensive overview of cavity dynamics and may provide a potential pathway to access multi-stable states by effectively varying the phase modulation.

Study on vortex-induced multimodal coupled vibration of arch bridge suspenders

The objective of this paper was to investigate the 2-DOF suspender response under the condition of vortex-induced force and reveal the multimodal coupling mechanism. Firstly, an elastically mounted segmental model of suspender was established. Wind tunnel experiments were conducted to obtain the time history displacement signals in cross-flow and in-line directions, the empirical parameters were obtained by identify those signals. The nonlinear partial differential motion equation of suspender with two degrees of freedom was established based on Hamilton's principle, which considered the dynamic strain, bending stiffness and vortex-induced force of suspender. The Galerkin method was used to discretize the nonlinear partial differential equations into nonlinear motion governing equations, which considered the first three order modes. A numerical method was used to solve the motion governing equation, the time history displacement curve, phase diagram, amplitude spectrum and Poincare map of the multi-modal responses in the cross-flow and in-line directions were obtained. With the weak coupling effect of nonlinear stiffness and vortex-induced force, the cross-flow and in-line responses demonstrate period doubling bifurcation, quasi-periodic vibration, period doubling vibration, crises and transient chaotic phenomena. However, with the strong coupling effect, the crises and transient chaos in response amplitude disappear. More importantly, planar/non-planar multimodal internal resonance were found in this work. With the weak multimodal coupling effect in suspender response, the low-order modal response is dominant; as the multimodal coupling effect increases, the high-order modal response becomes predominant. In addition, the system energy not only transfers from high-order modal response to low-order modal response, but also the system energy transfer from low-order modal response to high-order modal response. These conclusions are useful for the design and practical engineering of suspenders, which have high theoretical research value in understanding the mechanism of multimodal coupling effects on suspender response.

Five Low-Noise Stable Oscillators Referenced to the Same Multimode AlN/Si MEMS Resonator.

We report on the first experimental demonstration of five self-sustaining feedback oscillators referenced to a single multimode resonator, using piezoelectric aluminum nitride on silicon (AlN/Si) microelectromechanical systems (MEMS) technology. Integrated piezoelectric transduction enables efficient readout of five resonance modes of the same AlN/Si MEMS resonator, at 10MHz, 30MHz, 65MHz, 95MHz, and 233MHz with quality (Q) factors of 18600, 4350, 4230, 2630, and 2138, respectively. Five stable self-sustaining oscillators are built, each referenced to one of these high-Q modes, and their mode-dependent phase noise and frequency stability (Allan deviation) are measured and analyzed. The 10, 30, 65, 95 and 233MHz oscillators exhibit low phase noise of -116, -100, -105, -106 and -92dBc/Hz at 1kHz offset frequency, respectively. The 65MHz oscillator yields Allan deviation of 4×10-9 and 2×10-7 at 1s and 1000s averaging time, respectively. The 10MHz oscillator's low phase noise holds strong promise for clock and timing applications. The five oscillators' overall promising performance also suggests suitability for multimode resonant sensing and tracking. This work also elucidates mode dependency in oscillator noise and stability, one of the key attributes of mode-engineerable resonators.

Brain age prediction across the human lifespan using multimodal MRI data.

Measuring differences between an individual's age and biological age with biological information from the brain have the potential to provide biomarkers of clinically relevant neurological syndromes that arise later in human life. To explore the effect of multimodal brain magnetic resonance imaging (MRI) features on the prediction of brain age, we investigated how multimodal brain imaging data improved age prediction from more imaging features of structural or functional MRI data by using partial least squares regression (PLSR) and longevity data sets (age 6-85years). First, we found that the age-predicted values for each of these ten features ranged from high to low: cortical thickness (R = 0.866, MAE = 7.904), all seven MRI features (R = 0.8594, MAE = 8.24), four features in structural MRI (R = 0.8591, MAE = 8.24), fALFF (R = 0.853, MAE = 8.1918), gray matter volume (R = 0.8324, MAE = 8.931), three rs-fMRI feature (R = 0.7959, MAE = 9.744), mean curvature (R = 0.7784, MAE = 10.232), ReHo (R = 0.7833, MAE = 10.122), ALFF (R = 0.7517, MAE = 10.844), and surface area (R = 0.719, MAE = 11.33). In addition, the significance of the volume and size of brain MRI data in predicting age was also studied. Second, our results suggest that all multimodal imaging features, except cortical thickness, improve brain-based age prediction. Third, we found that the left hemisphere contributed more to the age prediction, that is, the left hemisphere showed a greater weight in the age prediction than the right hemisphere. Finally, we found a nonlinear relationship between the predicted age and the amount of MRI data. Combined with multimodal and lifespan brain data, our approach provides a new perspective for chronological age prediction and contributes to a better understanding of the relationship between brain disorders and aging.

A Novel Broadband ± 45° Dual-Polarized Cross-Dipole Antenna with Multimode Resonance

A novel broadband ± 45 ° dual-polarized cross-dipole antenna is presented for application in 2G, 3G, 4G, and sub-6 GHz 5G base station. A bent structure with a coplanar transmission line is used in the antenna design, which achieves multimode resonance, broadening the impedance bandwidth tremendously. Especially, it can work at 3 λ / 2 and 2 λ resonant modes without the impact of reverse current. The antenna covers the frequency spectra from 1.7 GHz to 3.8 GHz with an enhanced impedance bandwidth of roughly 76.4% and VSWRs < 1.65 at two ports. A gain of 8.3 ± 1.9 dBi and port-to-port isolation > 22.5 dB are attained in the operating frequency range. Additionally, the presented antenna has a very simple configuration and is easy to construct. A mechanical prototype of the antenna has been manufactured and measured. The experimental findings and the computational results are in good agreement.

Uncovering and Experimental Realization of Multimodal 3D Topological Metamaterials for Low-Frequency and Multiband Elastic Wave Control.

Topological mechanical metamaterials unlock confined and robust elastic wave control. Recent breakthroughs have precipitated the development of 3D topological metamaterials, which facilitate extraordinary wave manipulation along 2D planar and layer-dependent waveguides. The 3D topological metamaterials studied thus far are constrained to function in single-frequency bandwidths that are typically in a high-frequency regime, and a comprehensive experimental investigation remains elusive. In this paper, these research gaps are addressed and the state of the art is advanced through the synthesis and experimental realization of a 3D topological metamaterial that exploits multimodal local resonance to enable low-frequency elastic wave control over multiple distinct frequency bands. The proposed metamaterial is geometrically configured to create multimodal local resonators whose frequency characteristics govern the emergence of four unique low-frequency topological states. Numerical simulations uncover how these topological states can be employed to achieve polarization-, frequency-, and layer-dependent wave manipulation in 3D structures. An experimental study results in the attainment of complete wave fields that illustrate 2D topological waveguides and multi-polarized wave control in a physical testbed. The outcomes from this work provide insight that will aid future research on 3D topological mechanical metamaterials and reveal the applicability of the proposed metamaterial for wave control applications.

The value of multimodal functional magnetic resonance imaging in differentiating p53abn from p53wt endometrial carcinoma.

Endometrial carcinoma (EC) is the sixth most common cancer in women. P53 gene expression in patients with endometrial cancer can predict the efficacy and prognosis of patients with neoadjuvant therapy. To explore the value of multimodal magnetic resonance imaging (MRI) in differentiating p53 abnormal (p53abn) from p53 wild-type (p53wt) EC. Data from 47 EC patients, including 14 p53abn cases and 33 p53wt cases, were retrospectively analyzed. The preoperative MRI sequences included amide proton transfer weighted (APTw) imaging, T2 mapping, mDIXON-Quant imaging and diffusion-weighted imaging (DWI). After post-processing, APT, T2, transverse relaxation rate (R2*), fat fraction (FF) and apparent diffusion coefficient (ADC) maps were obtained. The APT, T2, R2*, FF and ADC values for lesions of the two groups of cases were measured by two observers who were blind to the pathological data. The APT value and R2* value in the p53abn group were higher than those in the p53wt group, while the ADC value was lower (all P < 0.05). There was no statistically significant difference in T2 value and FF value between the two groups (all P > 0.05). The area under curve of APT, R2*, ADC and combined APT + R2*+ADC values for identification of p53abn and p53wt EC were 0.739, 0.689, 0.718 and 0.820, respectively (all P > 0.05). APTw, mDIXON-Quant and DWI techniques can be usedfor quantitative identification of p53abn and p53wt EC. The multimodal MRI provides a new way for preoperative quantitative evaluation of EC molecular typing, which has certain clinical application value.

Experimental investigation on multi-mode resonances in a rectangular harbor

Physical experiments were conducted to investigate the oscillations in a rectangular harbor for different modes with the same resonant frequency. Two multimode resonances, that is, case A for modes (0, 2) and (3, 1) and case B for modes (1, 1) and (2, 0) excited by bichromatic waves, were examined. The results showed that the multimode resonance was excited. During the response process when the resonance is initially excited, the subharmonic energy mainly focused on mode (0, 2) for case A and mode (2, 0) for case B. With the continuous input of wave energy, periodic modulations for the infragravity waves in the harbor were observed, implying that the subharmonic energy transfers freely between the two modes in a quasi-steady state. During the damping process, with no waves, the subharmonic energy returns to the mode that occupies the response process. The phenomenon that the subharmonic energy concentrates in the same mode in the response and damping processes is possibly because these modes are more easily excited than the others.

Dual-Band Single-Pole Double-Throw Filtering Switch Using Multimode Cavity Resonators

A dual-band single-pole double-throw (SPDT) filtering switch using hybrid microstrip-cavity structure is proposed in this paper. Two rectangular cavities act as the multimode resonators, and the cross-shaped microstrip lines (MLs) are adopted to feed them. Then two filtering channels are constructed, while only one channel is supposed to be turned on in each operating state. For this purpose, PIN diodes are integrated into the two output MLs to switch the two channels arbitrarily. The channel using reversely biased PIN diodes is turned on with dual-band filtering response. On the contrary, the other channel using forward biased PIN diodes is switched off with high OFF-state suppression and channel isolation. The measurements indicate a dual-band filtering response along with below 0.75 dB insertion loss in the switched-on channel. And 38 dB suppression as well as 33.3 dB channel isolation is obtained in the switched-off channel. Benefitting from the hybrid microstrip-cavity structure, the bandwidths of the two bands could be adjusted independently. And meanwhile the two multimode cavities are shared by the two channels to compact the size. In this way, the proposed microstrip-cavity structure possesses a dual-band SPDT filtering switch response, flexible passbands and miniaturization.

Corrections to “Wideband Four-Way Filtering Power Divider With Sharp Selectivity and High Isolation Using Coshared Multi-Mode Resonators”

Corrections to “Wideband Four-Way Filtering Power Divider With Sharp Selectivity and High Isolation Using Coshared Multi-Mode Resonators”

MAS-Net:Multi-modal Assistant Segmentation Network For Lumbar Intervertebral Disc.

Objective.Despite advancements in medical imaging technology, the diagnosis and positioning of lumbar disc diseases still heavily rely on the expertise and experience of medical professionals. This process is often time-consuming, labor-intensive, and susceptible to subjective factors. Achieving automatic positioning and segmentation of lumbar intervertebral disc (LID) is the first and critical step in intelligent diagnosis of lumbar disc diseases. However, due to the complexity of the vertebral body and the ambiguity of the soft tissue boundaries of the LID, accurate and intelligent segmentation of LIDs remains challenging. The study aims to accurately and intelligently segment and locate LIDs by fully utilizing multi-modal lumbar magnetic resonance Images (MRIs).Approach.A novel multi-modal assistant segmentation network (MAS-Net) is proposed in this paper. The architecture consists of four key components: the multi-branch fusion encoder (MBFE), the cross-modality correlation evaluation (CMCE), the channel fusion transformer (CFT), and the selective Kernel (SK) based decoder. The MBFE module captures and integrates various modal features, while the CMCE module facilitates the fusion process between the MBFE and decoder. The CFT module selectively guides the flow of information between the MBFE and decoder and effectively utilizes skip connections from multiple layers. The SK module computes the significance of each channel using global pooling operations and applies weights to the input feature maps to improve the models recognition of important features.Main results.The proposed MAS-Net achieved a dice coefficient of 93.08% on IVD3Seg and 93.22% on DualModalDisc dataset, outperforming the current state-of-the-art network, accurately segmenting the LIDs, and generating a 3D model that can precisely display the LIDs.Significance.MAS-Net automates the diagnostics process and addresses challenges faced by doctors. Simplifying and enhancing the clarity of visual representation, multi-modal MRI allows for better information complementation and LIDs segmentation. By successfully integrating data from various modalities, the accuracy of LID segmentation is improved.

Band Dynamics of Multimode Resonant Nanophotonic Lattices with Adjustable Liquid Interfaces.

Subwavelength resonant lattices offer a wide range of fascinating spectral phenomena under broadside illumination. The resonance mechanism relies on the generation of lateral Bloch modes that are phase matched to evanescent diffraction orders. The spectral properties and the total number of resonance states are governed by the structure of leaky modes and the mode count. This study investigates the effect of interface modifications on the band dynamics and bound-state transitions in guided-mode resonant lattices. We provide photonic lattices comprising rectangular Si3N4 rods with a liquid film with an adjustable boundary. The band structures and band flips are examined through numerical simulations using the rigorous coupled-wave analysis (RCWA) method and analyzing the zero-order spectral reflectance as a function of the incident angle. The band structures and band flips are examined through numerical simulations, and the influences of the refractive index and the thickness of the oil layer on the band dynamics are investigated. The results reveal distinct resonance linewidths corresponding to different refractive indices of the oil layer. Furthermore, the effect of the oil thickness on the band dynamics is explored, demonstrating precise control over the number of propagating modes within the lattice structure. Theoretical simulations and experimental results are presented for a subwavelength silicon-nitride lattice combined with a liquid film featuring an adjustable boundary. The presence of a relatively thick liquid waveguiding region enables the emergence of additional modes, including the first four transverse-electric (TE) leaky modes, which produce observable resonance signatures. Through experimental manipulation of the basic lattice's duty cycle, the four bands undergo quantifiable band transitions and closures. The experimental results obtained within the 1400-1600 nm spectral range exhibit reasonable agreement with the numerical analysis. These findings underscore the significant role played by the interface in shaping the band dynamics of the lattice structure, providing valuable insights into the design and optimization of photonic lattices with adjustable interfaces.

Multi-mode optical chirality extremizations on the incident momentum sphere.

We study the momentum-space evolutions for chiral optical responses of multi-mode resonators scattering plane waves of varying incident directions. It was revealed, in our previous study [Phys. Rev. Lett.126, 253901 (2021)10.1103/PhysRevLett.126.253901], that for single-mode resonators the scattering optical chiralities characterized by circular dichroism (CD) are solely decided by the third Stokes parameter distributions of the quasi-normal mode (QNM) radiations: CD = S3. Here we extend the investigations to multi-mode resonators, and explore numerically the dependence of optical chiralities on incident directions from the perspectives of QNM radiations and their circular polarization singularities. In contrast to the single-mode regime, for multi-mode resonators it is discovered that CDs defined in terms of extinction, scattering and absorption generally are different and cannot reach the ideal values of ±1 throughout the momentum sphere. Though the exact correspondence between CD and S3 does not hold anymore in the multi-mode regime, we demonstrate that the positions of the polarization singularities still serve as an efficient guide for identifying those incident directions where the optical chiralities can be extremized.

An ultrathin triple‐band absorber for tuneable THz bio‐sensing

AbstractIn this paper, a multimode terahertz absorber is implemented using an ultrathin silicon ring with varying multimodal resonance. The rectangular silicon ring is providing three resonances with creating electromagnetic dipoles. The altering of these resonances is explicitly controlled with the help of a circular graphene ring. The graphene ring is used in the centre for tenability and to achieve perfect absorption. An equivalent circuit model is also presented and verified for the proposed structure. The design is intended to measure the glucose percentage in water. In addition, this can be used as a biosensor for the detection of malaria parasite percentage in water. A few important parameters like sensitivity and quality factors are considered to evaluate the performance of the said design. The sensitivity with analyte thickness is found to be 0.445 THz TU−1, 0.4255 THz TU−1, and 0.4305 THz TU−1. The corresponding quality factor is noted for the lower, middle, and upper bands as 235, 653, and 264 respectively. Further, the sensitivity and quality factors were measured just by changing the refractive index. The new estimated values are 0.480 THz RIU−1, 0.403 THz RIU−1, and 0.562 THz RIU−1 and corresponding quality factors are 203, 555, and 261 for lower, middle, and upper bands respectively. The design is also expected to flourish as a polarization‐insensitive absorber.

Comparison of Image Normalization Methods for Multi-Site Deep Learning

In this study, we evaluate the influence of normalization on the performance of deep learning networks for tumor segmentation and the prediction of the pathological response of locally advanced rectal cancer to neoadjuvant chemoradiotherapy. The techniques were applied to a multicenter and multimodal magnet resonance imaging data set consisting of 201 patients recorded at six centers. We implemented and investigated six different normalization methods (setting the mean and standard deviation, histogram matching, percentiles, combining percentiles and histogram matching, fixed window and an auto-encoder with adversarial loss using the imaging parameters) and evaluated their impact on four deep learning tasks: tumor segmentation, prediction of treatment outcome, and prediction of sex and age. The latter two tasks were implemented as a reference test. We trained a modified U-Net with different normalization methods in multiple configurations: on all images, images from all centers except one, and images from a single center. Our results show that normalization only plays a minor role in segmentation, with a difference in Dice of less than 0.02 between the best and worst performing networks. For the prediction of sex and treatment outcomes, the percentile method combined with histogram matching works best for all scenarios. The biggest difference in performance, depending on the normalization method, occurs for classification. In conclusion, normalization is especially important for small data sets or for generalizing to different data distributions. The deep learning method was superior to the classical methods only in a minority of cases, probably due to the limited amount of training data.

On chip optical neural networks based on MMI microring resonators for image classification

We propose a new on-chip optical neural network (OONN) based on multimode interference-microring resonators (MMI-RRs). The suggested structure eliminates the need for wavelength division multiplexers (WDM) to create an optical neuron on a single chip. New microring resonator structure based on 4×4 MMI coupler with a size of 24µm × 2900 µm is used for the basic elements of the computation matrix, as a result a higher bandwidth and free spectral range (FSR) can be achieved. The Si3N4 platform along with the graphene sheet is designed to modulate the signals and weights of the neural networks at a very high speed. The Si3N4 can provide wide range of operating wavelengths and can work directly with the wavelengths of color images. The structure's benefits include rapid computing speed, little loss, and the ability to handle both positive and negative values. The OONN has been applied to the MNIST dataset with a speed faster than 2.8 to 14x times compared with the conventional GPU methods.