Change In Quality Factor Research Articles

Magnetic sensitive mechanical response in CrSBr and its composite resonators

We study the mechanical response of bulk CrSBr in temperature using a CrSBr string resonator. We observe two abrupt changes in eigenfrequency and quality factor of the resonator with decreasing temperature, a strong one around 140 K due to an antiferromagnetic phase transition, and a weaker one around 200 K possibly related to a change of spin correlations. We find that the antiferromagnetic transition persists through a temperature window of 30 K rather than showing a narrow sharp change, indicating a gradual spin transition process. In addition, the quality factor exhibits an unexpected increase during the transition, which violates the theoretical prediction. Finally, we demonstrate that in a CrSBr/SiN composite resonator, its vibrational state is sensitively affected by the constituent CrSBr layer during the magnetic phase transitions. It reveals the potential of a composite resonator in both controlling its vibration state with and probing phase transitions of its constituent materials. Our study not only enriches the details about the antiferromagnetic phase transition in CrSBr, but also opens up possibility in magnetic sensing and in situ tuning using composite mechanical resonators.

Electrical field-induced Fano resonance tunability in photonic crystal slabs

The creation of tunable Fano resonances in a photonic crystal structure with a side-coupled nanocavity and a waveguide with a partially transmitting element is investigated in this paper. In the proposed structure, the nanocavity’s central hole is made up of two cylinders with different radii that are nested inside each other. The outer and inner cylinders are made of quartz and liquid crystal, respectively. The performance of this device is analyzed using the three-dimensional finite-difference time-domain. The transmission spectrum, resonance wavelength, and quality factor of the proposed structure are calculated for various applied voltages. It is demonstrated that as the applied voltage increases, the quality factor changes and the Fano resonance wavelength shifts. Based on the findings, a tuning range of 5.2 nm is achievable with an excellent transmission contrast within this range. The presented structure is appropriate for applications such as tunable switches and filters.

The effect of B-site ions on crystal structure evolution and microwave dielectric properties of gillespite-type SrCu0.95B0.05(B2+: Cu, Co, Mn, Ni, Mg, Zn)Si4O10

Gillespite-type SrCu0.95B0.05(B2+:Cu,Co,Mn,Ni,Mg,Zn)Si4O10 (SCBS) ceramics were prepared by high-temperature solid-state method. Their microwave dielectric properties and crystal structure evolution were studied by P–V-L theory, bond valence model, and X-ray photoelectron spectroscopy. Varying B2+ ion changed ionic polarizability and bond ionicity, causing dielectric constant εr of SCBS to change. The change in quality factor Q × f was explained by lattice energy, oxidation state of Cu, and internal strain/fluctuation. The temperature coefficient of resonator frequency τf was regulated by B–O bond length and valence. The optimal microwave dielectric properties were exhibited by SrCu0.95Mn0.05Si4O10 after sintering at 1050 °C: εr∼5.8 ± 0.03, Q × f∼65,589 ± 2611 GHz (@15.8 GHz), and τf ∼ -50 ± 4 ppm/°C. These materials show great potential application prospects for 5G/6G wireless communication.

Power Dependent Resonant Frequency of a Microwave Cavity Due to Magnetic Levitation

The fact that a magnet levitates above a superconductor is a fascinating consequence of the interaction between electromagnetic fields and the macroscopic quantum state of the superconductor. Such field-matter interactions, which include the Meissner and Josephson effects, combined with superconducting devices, such as low-loss superconducting microwave cavities, are emerging as key elements used in quantum computers. One technique that can be used to monitor the levitation of a magnet is to place the magnet within a superconducting microwave cavity and monitor the microwave resonance of that cavity. Here, we report measurements of the change in resonance frequency of the microwave cavity with the Meissner-levitated permanent magnet. The cavity resonance changes because the magnet perturbs the radio-frequency field inside the microwave cavity. The changes in resonant frequency and quality factor were measured as functions of input power and temperature. The observed power-dependent variations are explained in terms of the power dependence of the London penetration depth.

Beam quality factor of aberrated Laguerre-Gaussian optical beams.

The influence of aberrations on the beam quality factor of Laguerre-Gaussian beams is investigated. We derive analytical expressions for the beam quality factor due to astigmatism and spherical aberration. We show that the width of a Laguerre-Gaussian beam is a significant parameter that determines the aberration effects on the beam quality factor. For each aberration, we derive an expression for the width that separates the region where the beam quality factor changes infinitesimally and where it changes drastically. The validity of the analytical expressions is assessed by performing numerical simulations. There is excellent agreement between the analytical and numerical results.

Temperature Performance Study of SAW Sensors Based on AlN and AlScN.

In this paper, the temperature performance of AlN-SAW resonators and AlScN-SAW resonators is studied. They are simulated by COMSOL Multiphysics, and their modes and the S11 curve are analyzed. The two devices were fabricated using MEMS technology and tested using VNA, and the test results were consistent with the simulation results. Temperature experiments were carried out with temperature control equipment. With the change in temperature, the changes in S11 parameters, TCF coefficient, phase velocity, and quality factor Q were analyzed. The results show that the temperature performance of the AlN-SAW resonator and the AlScN-SAW resonator is very good, and both have good linearity. At the same time, the sensitivity of the AlScN-SAW resonator is greater by 9.5%, the linearity is greater by 15%, and the TCF coefficient is greater by 11.1%. The temperature performance is excellent, and it is more suitable as a temperature sensor.

Exfoliated Flexible Photonic Crystal Slabs for Refractive Index and Biomolecular Sensing

Using the optical transduction properties of one-dimensional photonic crystal slabs is a promising approach for label-free biosensing in the field of flexible and wearable biosensing. In this work we demonstrate the fabrication of flexible photonic crystal slabs (f-PCS) via an exfoliation method from rigid photonic crystal slabs. We investigate the processing effect on the optical properties and show that the optical resonances are maintained, but affected. The quality factor changes from 50 to 31 for the TE mode and from 187 to 136 for the TM mode after the process. We demonstrate use of f-PCS for refractive index sensing and achieve a limit of detection (LOD) of 3.6 E-4 refractive index units (RIU). Furthermore, we introduce vapor-phase functionalization of the f-PCS and show first results of biosensing of antibodies from diluted feline serum.

Cold-sintered NaCa2Mg2V3O12–Li2MoO4 microwave dielectrics for the design and fabrication of high-bandwidth antennas

Preparation of (1 – x)NaCa2Mg2V3O12–xLi2MoO4 (NCMVO-LMO; x = 0.4, 0.5, 0.6, 0.7) composites via cold sintering technique under 200 °C using uniaxial pressure of 450 MPa for 50 min is reported in this article. Microstructures of these composites suggest their enhanced densification with increased LMO concentration. Relative permittivity (εr) of (1 – x) NCMVO–xLMO ceramics varies from 7 to 8, and the quality factor (Qu × f) changes from 7000 to 13,500 GHz. A cylindrical dielectric resonator antenna (CDRA) and a microstrip patch antenna (MPA) were outlined, fabricated, and tried using the 0.4NCMVO–0.6LMO composite. CDRA and MPA exhibit excellent performance with centre frequencies of 13.24 and 5.48 GHz, maximum return losses of –36 and –31 dB, and maximum impedance bandwidths of 0.77 and 1.4 GHz, respectively. These values suggest that the fabricated antennas hold the potential to be a key component in future microwave communication systems, especially for 5G and Ku-band applications.

The Simulation and Design of an On-Chip Superconducting Millimetre Filter-Bank Spectrometer

Superconducting on-chip filter banks provide a scalable, space saving solution to create imaging spectrometers at millimetre and submillimetre wavelengths. We present an easy to realise, lithographed superconducting filter design with a high tolerance to fabrication error. Using a capacitively coupled lambda /2 microstrip resonator to define a narrow (lambda /Delta lambda = 300) spectral pass band, the filtered output of a given spectrometer channel directly connects to a lumped-element kinetic inductance detector. We show the tolerance analysis of our design, demonstrating <11% change in filter quality factor to any one realistic fabrication error and a full filter-bank efficiency forecast to be 50% after accounting for fabrication errors and dielectric loss tangent.

Investigation of the microwave dielectric properties of the Li4x/3Zn2−2xTi1+2x/3O4 system by P–V–L theory and vibration spectroscopy

Li 4x/3 Zn 2–2x Ti 1+2x/3 O 4 microwave dielectric ceramics with a spinel phase were prepared via a high-temperature solid-phase method. P–V–L theory, vibration spectra, and XPS were utilized to establish the links between the intrinsic and extrinsic factors and the microwave dielectric properties. According to the characterization, the change in permittivity ( ε r ) was ascribed to the increase in the average bond ionicity of Ti–O( Af iTi-O ) and the polar mode of the lattice vibration; the change in quality factor( Q × f ) resulted from the change in the Ti–O lattice energy ( AU Ti-O ) and existence of oxygen vacancy; the increase in temperature coefficient of the resonance frequency ( τ f ) was triggered by the increase in the Ti–O bond energy. The Li 0.6 Zn 1.1 Ti 1.3 O 4 ceramics (x = 0.45) sintered at 1125 °C finally obtained optimal microwave dielectric constants of ε r = 17.3, Q × f = 76,318 GHz and τ f = -58 ppm/°C.

Determination and Monitoring of Quality Parameters: A Detailed Study of Optical Elements of a Lens-Based Raman Spectrometer.

A lens-based Raman spectrometer is characterized by studying the optical elements in the optical path and we study the measure of aberration–diffraction effects. This is achieved by measuring the spectral resolution (SR) thus encompassing almost all optical elements of a spectrometer that are mostly responsible for such effects. An equation for SR is used to determine the quality factor Q which measures aberration/diffraction effects occurring in a spectrometer. We show how the quality factor changes with different spectrometer parameters such as grating groove density, the wavelength of excitation, pinhole width, charge-coupled device (CCD) pixel density, etc. This work provides an insight into the quality of a spectrometer and helps to monitor the performance of the spectrometer over a certain period. Commercially available spectrometers or home-built spectrometers are prone to misalignment in optical elements and can benefit from this work that allows maintaining the overall quality of the setup. Performing such experiments over a period helps to minimize the aberration/diffraction effects occurring as a result of time and maintaining the quality of measurements.

Label-free detection of virus-like particles employing rotationally symmetric nanowire array based whispering gallery and quasi-whispering gallery resonant modes onto a silicon platform.

In spite of tremendous advancements in modern diagnostics, there is a dire need for reliable, label-free detection of highly contagious pathogens like viruses. In view of the limitations of existing diagnostic techniques, the present theoretical study proposes a novel scheme of detecting virus-like particles employing whispering gallery and quasi-whispering gallery resonant modes of a composite optical system. Whereas whispering gallery mode (WGM) resonators are conventionally realized using micro-disk, -ring, -toroid or spherical structures, the present study utilizes a rotationally symmetric array of silicon nanowires which offers higher sensitivity compared to the conventional WGM resonator while detecting virus-like particles. Notwithstanding the relatively low quality factor of the system, the underlying multiple-scattering mediated photon entrapment, coupled with peripheral total-internal reflection, results in high fidelity of the system against low signal-to-noise ratio. Finite difference time domain based numerical analysis has been performed to correlate resonant modes of the array with spatial location of the virus. The correlation has been subsequently utilized for statistical analysis of simulated test cases. Assuming detection to be limited by resolution of the measurement system, results of the analysis suggest that for only about 5% of the simulate test cases the resonant wavelength shift lies within the minimum detection range of 0.001-0.01 nm. For a single virus of 160 nm diameter, more than 8 nm shift of the resonant mode and nearly 100% change of quality factor are attained with the proposed nanowire array based photonic structure.

Complex Permittivity and Permeability Extraction of Ferromagnetic Materials For Magnetically Tuned Microwave Circuits

Ferromagnetic materials, such as ferrites, are employed for magnetically tuned radio frequency (RF) circuits. Ferrites exhibit both electric permittivity and magnetic permeability and independent RF characterization of these two properties is crucial for accurate design and modeling of RF circuits. A method that independently extracts each property over Wi-Fi frequencies is presented here, where complex permittivity and permeability of ferrite nano-particles are extracted using resonance frequency sensitivity of a 3D printed metallic cavity to various samples under test and their placement in the cavity. Air-filled 3D printed rectangular cavity using acrylonitrile butadiene styrene (ABS) are shielded using copper sheets; the structure of air-filled cavity is designed to excite TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">101z</sub> as the dominant resonance mode that resonates at 2.4 GHz. A cylindrical shape material under test (MUT) was added to the cavity at different positions for high electric and magnetic fields, while the resonant frequency change and degradation in quality factor of the resonant cavity are employed for accurate independent extraction of electric permittivity and magnetic permeability of MUT. The sample was prepared with volumetric distribution of 60:40 nanoparticles to glue ratio. In particular, a 3D printed composite sample of ABS with NiFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> magnetic nanoparticles is placed in positions of high electric or high magnetic energy densities of the metallic cavity, while any changes in resonant frequency and its frequency selectivity are observed from the cavity insertion loss characteristics. Both perturbation theory (as analytical) and finite element method (as numerical) techniques are employed for extraction of complex permittivity and permeability of NiFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> . The perturbation theory provides accurate extraction, which is also numerically confirmed using curve fitting of the full wave simulated scattering parameters to the measured results.

A wireless passive pressure sensor using microstructured ferromagnetic films with tunable effective permeability

This paper presents a novel LC-based passive wireless flexible pressure sensor that employs microstructured ferromagnetic films with tunable effective permeability. The proposed device consists of a micromachined planar spiral coil and a polymer film with cilia arrays (CAs) realized by the ferrofluidic instability principle. The effective permeability of the polymer film can be tuned by deforming the CAs with externally applied pressure, which can be estimated in turn by detecting the resonant frequency of the device using the phase-dip technique. The fabrication parameters for synthesizing different dimensions and densities of CAs were investigated as well. Devices of different CA densities were measured and discussed. The measured results showed that the device quality factor and phase change both increased with applied pressure. Due to this characteristic, the proposed device is advantageous over typical capacitive LC-based devices and performs better in wireless interrogation while maintaining the sensitivity of pressure sensing.

Analysis of Magnetic Coupling Resonance Efficiency of Superconducting Radio Power String Familiar with Magnetic Resonance

This paper presents a superconducting wireless transmission system whose transmitting coil adopts superconducting material and receiving coil to adopt copper material which can solve the problem of transmission efficiency of wireless transmission system well. Firstly we analyze magnetic coupling resonant wireless transmission principle; then measure superconducting coil resistance and copper coil resistance calculate analyze system quality factor change with frequency. Finally experiment measurement of transmission efficiency of superconducting-copper magnetic coupling resonant wireless transmission system analyzes the relationship between transmission efficiency and axial offset and radial offset distance. Experimental results show that superconducting wireless transmission systems can improve transmission efficiency significantly compared with copper wireless transmission systems. Compared with copper wireless transmission systems, superconducting wireless transmission systems have at least 12.4% efficiency enhancement during axial offset, while at least 11.3% efficiency increases during radial migration. While short distance radial migration (1~4cm), superconducting wireless transmission systems have almost constant transmission efficiency. Provide some technical reference for Superconducting wireless transmission.

Mechanical resonance properties of porous graphene membrane; simulation study and proof of concept experiment

Mechanical resonance properties of porous graphene resonators were investigated by simulation studies. The finite element method was utilized to design the porous graphene membrane pattern and to calculate the mechanical resonance frequency and quality factor. The changes in the resonance frequency and quality factor were systematically studied by changing the size, number, and relative location of pores on the graphene membrane. Mass loss and carbon-carbon bond break were found to be the main competing parameters for determining its mechanical resonance properties. The correlation between the geometry and the damping effect on the mechanical resonance of graphene was considered by suggesting a model on the damping factor and by calculating the membrane deflections according to the pore location. Based on the simulation results, an optimal porosity and porous geometry were found that gives the maximum resonance frequency and quality factor. Suspended graphene with various number pore structures was experimentally realized, and their mechanical resonance behaviors were measured. The trend of changes in resonance frequency and quality factor according to the number of pores in the experiment was qualitatively agreed with simulation results.

Performance optimization of airliner cabin air filters

This study aims to design a cabin air filter with a high dust loading performance that is suitable for functioning under haze conditions. A longitudinal comparison study was carried out on the initial filtration performance and resistance change rate during the dust holding process of real cabin air filters with different structures (V-shape, Cylinder and Pleat-Plate filters). It was found that the Cylinder filter was better than the other two in terms of the initial quality factor and resistance change rate during operation. Based on the measured data, a calculation model was developed to predict the service life of the filter. The Cylinder filter shows a service life that is 17% longer than that of the V-shape filter. The energy consumption of the Cylinder filter over 6000 flight hours is lower than that of the V-shape and Pleat-Plate filters. Through the flow field analysis based on the filter structure, a preliminary qualitative analysis of the difference in filter performance is provided. For the Cylinder filter, the airflow steering and unique pleat structure enhance the dust holding capacity. We believe that the Cylinder filter is more suitable for areas with a high PM10 concentration in the atmospheric environment, such as China.

Nonlinear effects in superconducting thin film microwave resonators

We discuss how reactive and dissipative nonlinearities affect the intrinsic response of superconducting thin-film resonators. We explain how most, if not all, of the complex phenomena commonly seen can be described by a model in which the underlying resonance is a single-pole Lorentzian, but whose centre frequency and quality factor change as external parameters, such as readout power and frequency, are varied. What is seen during a vector-network-analyser measurement is series of samples taken from an ideal Lorentzian that is shifting and spreading as the readout frequency is changed. According to this model, it is perfectly proper to refer to, and measure, the resonant frequency and quality factor of the underlying resonance, even though the swept-frequency curves appear highly distorted and hysteretic. In those cases where the resonance curve is highly distorted, the specific shape of the trajectory in the Argand plane gives valuable insights into the second-order physical processes present. We discuss the formulation and consequences of this approach in the case of nonlinear kinetic inductance, two-level-system loss, quasiparticle generation, and a generic model based on a power-law form. The generic model captures the key features of specific dissipative nonlinearities, but additionally leads to insights into how general dissipative processes create characteristic forms in the Argand plane. We provide detailed formulations in each case, and indicate how they lead to the wide variety of phenomena commonly seen in experimental data. We also explain how the properties of the underlying resonance can be extracted from this data. Overall, our paper provides a self-contained compendium of behaviour that will help practitioners interpret and determine important parameters from distorted swept-frequency measurements.

Bio‐inspired nano rotor investigation based on UVLM

Nano rotor is of great value in military and civilian applications. Due to its nano size, it works at an ultra-low Reynolds number and aerodynamic performance deteriorates dramatically. The bio-inspired nano rotor is carried out to improve the rotor propulsive performance. Unsteady vortex lattice method (UVLM) model is established fully considering the influence of induced drag and wake vortex distortion on aerodynamic forces. The aim is to quickly and accurately simulate the flow field around the bio-inspired nano rotor and to efficiently perform the aerodynamic calculation to optimise the design of the bio-inspired rotor. The rotor parameters and motion parameters such as aspect ratio, taper ratio and camber are studied using UVLM. It is found that the aerodynamic performance of the rotor increased with the aspect ratio. The quality factor changes parabolically with the taper ratio and camber, and there is an optimal value for the ratio and camber, respectively. The influences of pitching angle and frequency are investigated as well. Results show that the bio-inspired motion improves the propulsion performance of nano rotor.

AGARNet: Adaptively Gated JPEG Compression Artifacts Removal Network for a Wide Range Quality Factor

Most of existing compression artifacts reduction methods focused on the application for low-quality images and usually assumed a known compression quality factor. However, images compressed with high quality should also be manipulated because even small artifacts become noticeable when we enhance the compressed image. Also, the use of quality factor from the decoder is not practical because there are too many recompressed or transcoded images whose quality factor are not reliable and spatially varying. To address these issues, we propose a quality-adaptive artifacts removal network based on the gating scheme, with a quality estimator that works for a wide range of quality factor. Specifically, the estimator gives a pixel-wise quality factor, and our gating scheme generates gate-weights from the quality factor. Then, the gate-weights control the magnitudes of feature maps in our artifacts removal network. Thus, our gating scheme guarantees the proposed network to perform adaptively without changing the parameters according to the change of quality factor. Moreover, we exploit the Discrete Cosine Transform (DCT) scheme with 3D convolution for capturing both spatial and frequency dependencies of images. Experiments show that the proposed network provides better performance than the state-of-the-art methods over a wide range of quality factor. Also, the proposed method provides robust results in real-world scenarios such as the manipulation of transcoded images and videos.