Resonance Quality Research Articles

Cavity Optomechanics with Anderson-Localized Optical Modes.

Confining photons in cavities enhances the interaction between light and matter. In cavity optomechanics, this enables a wealth of phenomena ranging from optomechanically induced transparency to macroscopic objects cooled to their motional ground state. Previous work in cavity optomechanics employed devices where ubiquitous structural disorder played no role beyond perturbing resonance frequencies and quality factors. More generally, the interplay between disorder, which must be described by statistical physics, and optomechanical effects has thus far been unexplored. Here, we demonstrate how sidewall roughness in air-slot photonic-crystal waveguides can induce sufficiently strong backscattering of slot-guided light to create Anderson-localized modes with quality factors as high as half a million and mode volumes estimated to be below the diffraction limit. We observe how the interaction between these disorder-induced optical modes and in-plane mechanical modes of the slotted membrane is governed by a distribution of coupling rates, which can exceed g_{o}/2π∼200 kHz, leading to mechanical amplification up to self sustained oscillations via optomechanical backaction. Our Letter constitutes the first steps towards understanding optomechanics in the multiple-scattering regime and opens new perspectives for exploring complex systems with a multitude of mutually coupled degrees of freedom.

Quasi-Guided Modes Supported by a Composite Grating Structure with Alternating Element Widths

The efficiency of many optical processes is significantly dependent on the magnitude of the electric field. In this context, many artificially made resonating structures have been investigated to enhance light–matter interactions and facilitate the creation of practical applications. While metal–based terahertz metamaterials have been extensively investigated for this purpose, their performances are mainly limited by the poor confinement of terahertz waves on metal surfaces, exhibiting low resonance quality factors. In this work, we propose and investigate a simple yet novel scheme of enhancing wave–matter interactions in the terahertz region by exploiting the phenomenon of quasi–guided modes. The quasi-guided modes with ultra–high quality factors and huge local field enhancement can be achieved by manipulating the guided modes supported by a slab waveguide. The guided modes with the dispersion lines below the light line have infinite Q factors and can not be accessed from external space. By using a new type of composite grating composed of two ridge grating arrays with alternating ridge widths, the grating period is doubled, leading to a folding of the first Brillouin Zone and the flipping of the dispersion lines to be above the light line. Then, the guided modes will be transitioned into new quasi–guided modes with the possibility of free–space excitation while the Q factors are determined by the level of period–doubling perturbation. The presented results of realizing quasi–guided modes can be extended to other structures, providing a novel means of manipulating light–matter interactions.

Vocal Tract Resonance Detection at Low Frequencies: Improving Physical and Transducer Configurations

Broadband excitation introduced at the speaker's lips and the evaluation of its corresponding relative acoustic impedance spectrum allow for fast, accurate and non-invasive estimations of vocal tract resonances during speech and singing. However, due to radiation impedance interactions at the lips at low frequencies, it is challenging to make reliable measurements of resonances lower than 500 Hz due to poor signal to noise ratios, limiting investigations of the first vocal tract resonance using such a method. In this paper, various physical configurations which may optimize the acoustic coupling between transducers and the vocal tract are investigated and the practical arrangement which yields the optimal vocal tract resonance detection sensitivity at low frequencies is identified. To support the investigation, two quantitative analysis methods are proposed to facilitate comparison of the sensitivity and quality of resonances identified. Accordingly, the optimal configuration identified has better acoustic coupling and low-frequency response compared with existing arrangements and is shown to reliably detect resonances down to 350 Hz (and possibly lower), thereby allowing the first resonance of a wide range of vowel articulations to be estimated with confidence.

Surface roughness in finite-element meshes: application to plasmonic nanostructures

Photonic and plasmonic nanostructures almost unavoidably exhibit some degree of surface roughness for which the details depend on the fabrication process. A corresponding quantitative modeling thus requires the separation of numerical errors from the effects of roughness as well as the systematic construction of rough surfaces with prescribed properties. Here, we present a practical approach for constructing meshes of general rough surfaces with given autocorrelation functions based on the unstructured meshes of nominally smooth surfaces. The approach builds on a well-known method to construct correlated random numbers from white noise using a decomposition of the autocorrelation matrix. We discuss important details pertaining to the application of the approach for modeling of surface roughness and provide a corresponding software implementation. As an example application, we demonstrate the impact of surface roughness on the resonance frequencies and quality factors of a plasmonic nano-sphere dimer using an open-source boundary finite-element Maxwell solver. The approach can be utilized within a broad range of numerical methods to analyze the effects of surface roughness in various fields of science and engineering.

LINKAGES NASCENT ENTREPRENEURSHIP AND KNOWLEDGE QUALITY RESONANCE: EXPLORE VOLUNTARY CO-CREATION FROM SERVICE DOMINANT LOGIC

This research aims to explore a new conceptual model capable of filling the research gap on the experience of nascent entrepreneurs and the quality of knowledge resonance, which centered on exploring voluntary co-creation of shared value. Data were obtained from the experience of 232 start-up multisectoral companies in Java Island, Indonesia.The findings of this study contribute empirically and practically to the knowledge needed to investigate the creation of shared value. The results showed that the direct impact experienced by nascent entrepreneurs is negatively correlated, while the relationship associated with quality resonance of knowledge to the performance of business innovation is positive. Secondly,the concept of the model is proven by the high willingness to explore voluntary co-creation from service-dominant logic to bridge the negative correlation gap of the experience of nascent entrepreneurs. Thirdly, the direct impact led to the voluntary creation of shared value complements with limitations on the dominant service logic of the optional co-production into a co-creation concept called value-in-use. This model instils an attitude on the importance of voluntary exploring co-creation of high nascent entrepreneur experience and the quality knowledge resonance.

Motion artifact reduction for magnetic resonance imaging with deep learning and k-space analysis.

Motion artifacts deteriorate the quality of magnetic resonance (MR) images. This study proposes a new method to detect phase-encoding (PE) lines corrupted by motion and remove motion artifacts in MR images. 67 cases containing 8710 slices of axial T2-weighted images from the IXI public dataset were split into three datasets, i.e., training (50 cases/6500 slices), validation (5/650), and test (12/1560) sets. First, motion-corrupted k-spaces and images were simulated using a pseudo-random sampling order and random motion tracks. A convolutional neural network (CNN) model was trained to filter the motion-corrupted images. Then, the k-space of the filtered image was compared with the motion-corrupted k-space line-by-line, to detect the PE lines affected by motion. Finally, the unaffected PE lines were used to reconstruct the final image using compressed sensing (CS). For the simulated images with 35%, 40%, 45%, and 50% unaffected PE lines, the mean peak signal-to-noise ratio (PSNRs) of resulting images (mean±standard deviation) were 36.129±3.678, 38.646±3.526, 40.426±3.223, and 41.510±3.167, respectively, and the mean structural similarity (SSIMs) were 0.950±0.046, 0.964±0.035, 0.975±0.025, and 0.979±0.023, respectively. For images with more than 35% PE lines unaffected by motion, images reconstructed with proposed algorithm exhibited better quality than those images reconstructed with CS using 35% under-sampled data (PSNR 37.678±3.261, SSIM 0.964±0.028). It was proved that deep learning and k-space analysis can detect the k-space PE lines affected by motion and CS can be used to reconstruct images from unaffected data, effectively alleviating the motion artifacts.

Operando monitoring of gas drying by adsorption on supported ionic liquids: Determination of velocity of adsorption front by microwaves

For adsorption-based gas drying to reach very low dew points, ionic liquids (ILs) immobilized on solid porous supports are promising materials. Prior investigations with the IL 1-ethyl-3-methylimidazolium methanesulfonate ([EMIM][MeSO3]) show high absorption capabilities for water (vapour) and low regeneration (desorption) temperatures (< 100 °C). Due to the negligible evaporation losses of this IL combined with a high thermal stability and low melting point, [EMIM][MeSO3] is ideal for immobilization on highly porous supports. In this work, the IL covers at least a monolayer of the substrate (here silica), thereby filling about 30 % of the pores with the IL. Water then mainly (ab)sorbs in the IL and practically not adsorbs on the surface of silica. In the presence of water, the dielectric losses of the supported IL increase strongly and can therefore be measured by microwave perturbation methods. For this purpose, a quartz tube containing the fixed-bed of the supported IL was placed in the radial center of a microwave resonator operating in a mode so that the electric field strength varies in axial direction along the bed. During sorption experiments, the electrical signals measured with a network analyzer allowed to track the sorption front, to calculate the velocity of the moving front, and to detect the breakthrough of water vapor. The validation of this method was accomplished by simultaneously measuring the humidity of the carrier gas at the in- and outlet of the packed bed by humidity sensors. The water partial pressure (carrier gas N2), the temperature, and the gas velocity were varied in a range relevant for gas drying (5–15 mbar; 40–60 °C; 0.05–0.30 m s−1). The results demonstrate that microwave-derived parameters, like resonant frequency or quality factor, are suitable to locate the sorption front along the fixed-bed and to calculate the front velocity and the breakthrough time.

Термообработка слизистых субпродуктов под воздействием электрофизических факторов: разработка установки

Low efficiency of equipment for heat treatment, disinfection and removal of unpleasant odour of substandard mucous by-products urges the development of an installation that provides for the complex effect of ultra-high frequency electromagnetic field, ozone and bactericidal flow of ultraviolet rays. The paper presents the technology and describes the installation developed by the authors. The installation ensures electromagnetic safety and uniformity of loading according to the penetration depth of the wave. The duration of raw material treatment is matched with the specific power of the microwave generator, the power of the lamps and with the rotation frequency of the compartment disc. The electric field strength has been studied in the CST Microwave Studio program. The developed installation contains a resonator in the form of a flattened spheroid with diameters of the main axes multiple of half the wavelength. Magnetrons are placed on the upper surface of the spheroid along the perimeter. On the inner surface of the spheroid, where there are corona needles, ring electro-gas-discharge lamps powered from pulsed modeled high-frequency generators are uniformly installed along the perimeter through the gap. The source of radiation in the bactericidal lamp is an electric discharge in a mixture of mercury vapour and argon. A fluoroplastic perforated disc is installed at the level of the large diameter of the spheroid, on which mucous by-products are treated. The conducted research shows that the intrinsic factor of quality of the spheroid resonator is 9000. The heat treatment and disinfection of raw materials is most effective at the plant productivity of 50 kg/h, electric field strength of 3 to 4 kV/cm, disc rotation frequency of 0.17 to 0.2 rpm and a specific power of the microwave generator of 1.2 W/g. Power consumption amounted to 6.6 kW, while energy costs were 0.132 kW∙h/kg.

Inverse problem to estimate lips parameters values of outward-striking trumpet model for successive playing registers.

The objective of this work is to estimate by inverse problem lip parameters values of trumpet model so that the oscillation thresholds for successive playing registers occur for the same blowing pressure as the one measured on several trumpet players. The lips vibration is modeled through an oscillator including unknown parameters such as resonance frequency, quality factor, surface mass, stiffness, and opening at rest of the lips. The oscillation threshold is calculated through linear stability analysis of the outward-striking model including the nonlinear coupling with the bore of the trumpet. It appears that many combinations of parameter values are suitable to obtain the same blowing pressure at threshold as in the experiments. According to the analysis of the possible parameter values, some hypotheses are formulated about the playing strategies used by the trumpeter to select the different registers of the instrument. In addition to the resonance frequency of the lips, controlling the lips opening at rest appears to be a viable strategy to match experimental oscillation thresholds in terms of blowing pressure. Numerical values for the lips parameters are given and through sound synthesis, allow the successive registers of the trumpet to be played.

A Novel Magnetic Resonance Quality Assurance Phantom (KMRP-4): Multi-Site Comparison With the American College of Radiology Phantom

A Novel Magnetic Resonance Quality Assurance Phantom (KMRP-4): Multi-Site Comparison With the American College of Radiology Phantom

Investigation of Optical-Switching Mechanism Using Guided Mode Resonances

Recently, photonic crystals have paved the way to control photonic signals. Therefore, this research numerically investigated the design of the optical switch using the guided-mode resonances in photonic crystals operating in a communication window around 1.55 μm. The design of the device is based on a dielectric slab waveguide to make it compatible with optical waveguides in photonic circuits. Moreover, two signals are used and are termed as the data signal and control signal. The data signal is coupled into the optical waveguide using an out-of-the-plane vertical coupling mechanism, whereas the control signal is index-guided into the optical waveguide to amplify the data signal. The switching parameters of the optical switch are adjusted by changing the number of the photonic crystal periods and implementing a varying radius PhC-cavity within the middle of the PhC-lattice, where the optical characteristics in terms of resonant wavelength, reflection peaks, linewidth, and quality factor of the data signal can be adjusted. The numerical simulations are carried out in open-source finite difference time domain-based software. Congruently, 7% optical amplification is achieved in the data signal with a wavelength shift of 0.011 μm and a quality factor of 12.64. The amplification of the data signal can be utilized to implement an optical switching mechanism. The device is easy to implement and has great potential to be used in programmable photonics and optical integrated circuits.

Transformer-based multilevel region and edge aggregation network for magnetic resonance image segmentation

To improve the quality of magnetic resonance (MR) image edge segmentation, some researchers applied additional edge labels to train the network to extract edge information and aggregate it with region information. They have made significant progress. However, due to the intrinsic locality of convolution operations, the convolution neural network-based region and edge aggregation has limitations in modeling long-range information. To solve this problem, we proposed a novel transformer-based multilevel region and edge aggregation network for MR image segmentation. To the best of our knowledge, this is the first literature on transformer-based region and edge aggregation. We first extract multilevel region and edge features using a dual-branch module. Then, the region and edge features at different levels are inferred and aggregated through multiple transformer-based inference modules to form multilevel complementary features. Finally, the attention feature selection module aggregates these complementary features with the corresponding level region and edge features to decode the region and edge features. We evaluated our method on a public MR dataset: Medical image computation and computer-assisted intervention atrial segmentation challenge (ASC). Meanwhile, the private MR dataset considered infrapatellar fat pad (IPFP). Our method achieved a dice score of 93.2% for ASC and 91.9% for IPFP. Compared with other 2D segmentation methods, our method improved a dice score by 0.6% for ASC and 3.0% for IPFP.

Non‐local low‐rank constraint‐based self‐consistent PMRI reconstruction using eigenvector maps

AbstractEigenvector‐based SPIRiT (ESPIRiT) can estimate multiple sets of coil sensitivity maps from the calibration matrix constructed from the auto‐calibration data. Recently, the L1 norm and total variation were combined with the ESPIRiT model to improve the reconstruction quality of magnetic resonance (MR) images. To further improve the reconstruction performance, the non‐local low‐rank regularisation term is incorporated into the ESPIRiT model (NLR‐ESPIRiT) is proposed. The proposed NLR‐ESPIRiT model takes full advantage of the non‐local self‐similarity features of MR images. The resulting optimisation problem can be transformed into a gradient problem and a denoising problem with low‐rank constraints using the operator splitting technique. The weighted nuclear norm (WNN) is applied as a surrogate of the rank. Then the denoising subproblem with the WNN can be effectively solved by using the alternating direction method of multipliers technique. For practical applications, a parameter‐selecting method is proposed to obtain almost optimal parameters for the same kind of MR images. Simulation experiments on in vivo data sets demonstrate that the proposed NLR‐ESPIRiT outperforms all competing traditional model‐based algorithms in terms of three objective metrics and visual comparison.

A modified AMC-based antenna sensor for contactless measurement of complex permittivity

The paper proposes a modified artificial magnetic conductor (M-AMC)-based antenna sensor for retrieving the complex permittivity of material under test (MUT). The antenna sensor measurement system is composed of a coplanar waveguide (CPW) antenna and a M-AMC structure. The M-AMC structure consists of a 3×3 array, and each unit cell is fabricated by two-layer dielectric substrates. The M-AMC unit cell is evolved from the traditional square unit one, and in each cell, four bent microstrip lines are embedded in the middle plane of M-AMC structure to connect the top square metallic patch through metallic holes. Compared with traditional AMC structure, the added bent microstrip line can increase the current path. Besides, four complementary split-ring resonators (CSRRs) are etched on the top plane of each unit to improve the density of electrical field. A large metallic patch covers the bottom plane of M-AMC. The resonant frequency of M-AMC structure is reduced a lot than the traditional one, which is beneficial to realize miniaturization. In measurement, the antenna is placed on the upper surface of M-AMC structure with an appropriate distance, and the MUT is placed on top plane of M-AMC. The MUTs with different thicknesses and complex permittivity will alter the resonant frequency and quality factor of the antenna sensor. Experiment is carried out to demonstrate the performances of proposed antenna sensor. An average sensitivity of 1.89 % is achieved and the maximum error is less than 3.516 % in extracting the real permittivity. All in all, the proposed antenna sensor has a potential superiority in the scope of material characterization.

Microwave Cylindrical Cavity Resonator Sensor for Detection and Characterization of Contaminants in Lubricating Oil

Accurate monitoring of contaminants, such as wear particles in lubricating oil, is critical for the efficient maintenance of engines. Here, a TE011-mode cylindrical cavity resonator-based sensor system is presented. In the measurement, a glass test tube was used to contain the oil sample under test and placed in the center of the cavity. Particles in oil change the dielectric properties and perturb the resonance parameters, thereby achieving sensing. Sensitivity to both the presence of conductive and nonconductive powders is demonstrated. Linear relationships between the powder weight and the quality factor are established. Hence, the degree of contamination can be better evaluated compared with existing microwave sensors. Powder differentiation can be achieved using the resonance frequency and quality factor. In addition, analytical modeling of the sensing system incorporating field analysis is proposed, and the effective permittivity of the mixture can be determined. The sensor developed is compact, portable, easy to implement, complementary to other approaches for liquid evaluation, and has the potential for high-throughput online measurement.

Metal–ceramic composite structures for fabrication of high power density plasmonic devices

The recent decade brought many advances to plasmonics, but high power density plasmonic antennas designed to behave as heaters or operate in high temperature environments are still facing material stability challenges preventing their ultimate use. Gold has been the optimal choice among plasmonic materials but experiences morphology changes at temperature that result in device efficiency reduction and failure. Bulk titanium nitride has been explored as a solution but has deal-breaking tradeoffs in device quality factor. In this paper, we explore via proof-of-concept the use of a metal–ceramic composite structure to determine whether a bulk Au nanorod can provide strong plasmonic resonances while coated with an ultrathin conformal layer of titanium nitride or silica to provide morphological stability and sufficient plasmonic activity without excessive resonance quality degradation. We show SEM-level morphological stability for temperatures up to 500 °C with coatings below 4 nm. Computer modeling suggests the ultrathin titanium nitride has detrimental effects on the strong plasmonic resonances of a Au nanorod. We then looked into other possible coatings for solutions to stabilize high power density plasmonic antennas including plasmonic oxides, metal adhesion layers, and silica, the latter appearing to be the best option while lowering the overall peak electric field intensity, the silica increases the electric field intensity at its boundary.

Low-loss and temperature stable (1-x)Ba3P2O8-xMg2B2O5 composite ceramics with low sintering temperature

In this study, the Ba3P2O8 and Mg2B2O5 were fabricated by the solid-state reaction method separately, and the (1-x)Ba3P2O8-xMg2B2O5 (x = 0.2–0.4) low-temperature co-fired ceramic (LTCC) materials were obtained in the sintering temperature range of 880–960 °C. The phase compositions, microstructures, elemental compositions, and microwave dielectric properties of the (1-x)Ba3P2O8-xMg2B2O5 composite ceramics were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and TE01δ mode dielectric resonator method, respectively. The results revealed that the Mg2B2O5 phase and Ba3P2O8 phase could coexist well in the (1-x)Ba3P2O8-xMg2B2O5 composite ceramics without formation of any new phases. The abnormal grain growth of Ba3P2O8 grains was inhibited by the addition of Mg2B2O5. In addition, through composition of Ba3P2O8 and Mg2B2O5, the temperature coefficient of resonant frequency (τf) and quality factor (Q×f) were effectively optimized, and the sintering temperature was reduced to 880–960 °C. The optimal performance of 0.8Ba3P2O8-0.2Mg2B2O5 composite ceramic was achieved at a sintering temperature of 920 °C, τf = −1.9 ppm/°C, Q×f = 61,250 GHz, and a low permittivity εr = 10.7. The chemical compatibility test demonstrated that the composite ceramic could coexist well with silver, which indicated that the 0.8Ba3P2O8-0.2Mg2B2O5 composite ceramic is a candidate LTCC material with wide application prospects.

Enhancement of second-harmonic generation from Fano plasmonic metasurfaces by introducing structural asymmetries.

Resonant plasmonic metasurfaces have attracted much attention for great potential in augmenting nonlinear optical conversion at the nanoscale and thus related sensing and integrated optics applications. In this work, we use the nonlinear scattering theory to numerically investigate enhanced second-harmonic generation (SHG) from Fano metasurfaces which consist of gold asymmetric double-bars. We find that the Fano resonance at the fundamental wavelength boosts the nonlinear response by more than a factor of 60. On this basis, by introducing translational and rotational structural asymmetries, the SHG signal is further amplified because of the broken mirror symmetry. More specifically, under the optimal condition, the previously suppressed SHG component can be greatly released and play a more important role compared to the original existing SHG component in an extra 6-fold enhancement in total SHG intensity. The 360-fold enhancement by tailoring both resonance quality and structural asymmetries indicates the clear and important roles of both linear resonance and local-field distribution in reaching the largest SHG emission. Our results are a step towards enlarging SHG responses of more complex plasmonic nanostructures.

Effects of Resonant Voice Therapy on Perceptual and Acoustic Source and Tract Parameters – A Preliminary Study on Indian Carnatic Classical Singers

The aim of the study was to examine the effects of resonant voice therapy (RVT) on the vocal resonance of trained Carnatic singers. The specific objectives were to evaluate the effects of resonant voice therapy on the auditory perceptual judgments and acoustic source and tract parameters before and after RVT on phonation and sung voice samples. Six vocally healthy trained Carnatic singers, three males and three females aged 18-25 years (M=23; S.D=2.09) participated in the study. All the participants were assigned to a 21-days-long Resonance Voice Therapy (RVT) training program. The participants' pre and post training phonation and sung samples were subjected to auditory perceptual analysis and acoustic analysis. The results revealed that the post training auditory perceptual ratings of the phonation task showed a statistically significant difference from the pre training scores (Z= 2.35; P=0.019). While for the singing task, the post training perceptual ratings were not significantly different from the pre training perceptual rating scores (Z= 2.66; P=0.08). A significant difference was observed between the pre and post training values for all the measured acoustic parameters of the phonation task. In singing task, though the fundamental frequency, third and fourth formant frequencies showed no significant difference in the pre and post training conditions (P > 0.05), the parameter of- difference between the first formant frequency and the fundamental frequency showed a significant decrease (P=0.028). The effects of resonant voice production led to a high vocal economy, as evidenced from the improved source and filter acoustic parameters. Indication for formant tuning through vocal tract modifications, probably an enlarged pharyngeal area resulting in increased resonant voice quality in both phonation and singing tasks, is inferred from these results.

Niobium-tantalum oxide as a material platform for linear and nonlinear integrated photonics.

Here we realize the first reported integrated photonic devices fabricated using sputtered niobium-tantalum oxide films. Sputtered niobium-tantalum oxide films are highly promising for integrated photonics as they are scalable to high volume manufacturing, possess high refractive index, and are transparent in the ultraviolet through near infrared wavelength range. At a wavelength near 1550 nm, we observe propagation losses as low as 0.47 dB/cm in waveguides and ring resonators with resonator quality factors as high as 860,000. We also characterize the nonlinear performance of these films and find a Kerr coefficient (n2) of 1.2 ( ± 0.2) × 10-18 m2/W. With this high Kerr coefficient we demonstrate optical parametric oscillation in a ring resonator and supercontinuum generation in a waveguide.