Q-factor Of Resonator Research Articles

Microwave heating of slaughterhouse confiscations to increase the feed value

In the production of cooked feed, non-food waste from the meat industry is taken. The purpose of the research is to preserve the feed value of cooked feed during ultrahigh-frequency heat treatment. Implementation of design criteria for installations and resonators; evaluation of operating modes using multi-criteria regression models; justification of electrodynamic parameters and operating modes of installations. for effective work in a farm environment. Various plant designs are proposed. Based on the criteria: continuity of technological processes of grinding, dewatering, heat treatment and disinfection of raw materials; high intrinsic Q-factor of resonators; high electric field strength in raw materials; achievement of bactericidal effect; radio-tightness of the installation and uniform distribution of the electric field in the resonators-the optimal installation is selected.

Ridge resonators: impact of excitation beam and resonator losses.

Photonic resonators based on bound states in the continuum are attractive for sensing and telecommunication applications, as they have the potential to achieve ultra-high Q-factor resonators in a compact footprint. Recently, ridge resonators - leaky mode resonators based on a bound state in the continuum - have been demonstrated on a scalable photonic integrated circuit platform. However, high Q-factor ridge resonators have thus far not been achieved. In this contribution, we investigate the influence of excitation beam width and optical losses on the spectral response of ridge resonators. We show that for practical applications, the space required of the excitation beam is the limiting factor on the highest achievable Q-factor.

Supercavity Modes in Dielectric Resonators Excited by Two Current Sources

Detailed mechanisms are studied for achieving high quality factors (Q-factor) of high index resonators that exhibit strong confinement of electromagnetic fields and low loss. Exciting supercavity modes is a promising technique to increase the Q-factor in these resonators. Conventional techniques achieve supercavity modes by optimizing material properties and dimensions of such resonators. On the other hand, this work demonstrates that exciting resonators with more complex nearfield current sources instead of a single loop or patch, leads to strong supercavity modes for smaller resonators. Simulation results indicate that Q-factors achieved with the proposed method can be at least 3 times higher than with a conventional single one.

An ultra-high sensitive plasmonic refractive index sensor using an elliptical resonator and MIM waveguide

In this paper, an elliptical resonator coupled to a straight metal-insulator-metal waveguide through a silicon layer is used for sensing application. The finite-difference time-domain method is used for the numerical investigation of the proposed structure. Such a structure demonstrates a multi resonance mode in the transmission spectrum. Based on the obtained results, the sensitivity can be reached to a value as high as 550 nm per refractive-index unit with a high FOM value of 282.5 RIU −1 around the resonance wavelength of 592 nm. In this structure, in addition to using a high Q-factor resonator, the resonance profile is localized and concentrated on the analyte to achieve an ultra-high sensitive refractive index sensor. Also, the effect of structural parameters on the transmission spectrum is investigated by sweeping them. Taking into account the obtained notable specifications such as ultra-high sensitivity and simplicity of the design and fabrication process, the presented structure can be employed in optical integrated circuits , particularly in high sensitivity sensors. • A novel plasmonic structure for detection of refractive index is proposed. • The designed topology is based on an elliptical resonator coupled to a straight MIM waveguide through a silicon layer. • A high FOM value of 282.5, a high sensitivity value of 550 nm/RIU, and a small FWHM value of 1.947 nm are obtained. • In addition to using a high-Q factor resonator, the resonance profile is localized on the analyte to achieve a high FOM. • The proposed structure benefits from simplicity in the design and fabrication process.

Efficient magnetic-coupling excitation of LSSPs on high-Q multilayer planar-circular-grating resonators.

Recently, ultrathin localized spoof surface plasmon (LSSP) resonators are found to have intrinsic defects of relatively low quality factors (Q-factors) because of unavoidable material and radiation losses. In this paper, multilayer structures of planar-circular-grating resonators and their magnetic-coupling schemes are proposed to achieve effective excitation of high-Q LSSPs modes. By adopting the multilayer structures with air between the layers, the power dissipation effected by both material and radiation losses is significantly suppressed. Experimental results show that the Q-factors could reach more than 200 and the excitation efficiencies could reach more than 90%. Numerical simulations show the distribution of the electromagnetic field and illustrate the principle of magnetic coupling. Besides, the Q-factors of resonators with different structural parameters were measured and analyzed. This study aims to provide some inspirations on planar gyro-devices and to improve the performance of existing applications, such as sensors and filters.

Influence of the Surface Roughness of a Silicon Disk Resonator on Its Q-Factor

This article presents a silicon disk resonator of the whispering-gallery-mode (WGM) type. The calculated Q-factor of the silicon WGM resonator was 107. Two methods of studying the surface roughness of a silicon WGM resonator with a nonlinear profile by means of Helios 650 scanning electron microscope and Bruker atomic force microscope (AFM) are presented. The results obtained by the two methods agreed well with each other. A comparison of the surface roughness values of WGM resonators manufactured using different technological approaches is presented. Based on the obtained data, a preliminary estimated Q-factor calculation of the resonators was performed, which was refined by numerical calculation using the finite-difference time-domain (FDTD) method. The effect of the surface roughness of the resonator on its Q-factor was found. Reducing the surface roughness of the resonator from 30 nm to 1–2 nm led to an increase in its Q-factor from 104 to 107.

Low loss dielectric measurements in the frequency range 1–70 MHz by using a vector network analyser

The resonance of a coil inductor and a parallel-electrode capacitor can be used to determine the permittivity and loss angle of sheets of material at RF frequencies. By using high-stability instrumentation to measure resonant frequency and Q-factor, the loss angle of very low-loss materials can be determined with a resolution of below 10 microradians. In the 1970s much work went into developing Q-meter-based systems, based on series resonance, which were typically used for measuring the loss angle of polymers such as polyethylene. These systems were also used for measuring ceramics used as RF windows in prototype fusion reactors. This paper describes how one of these systems was updated to replace the now obsolete Q-meter with a vector network analyser (VNA), using parallel resonance. A second aspect to the work is calculation of the fringing (edge) capacitance between the electrodes, which are unguarded, by using MIT FastCap software. This enables measurements obtained by the equivalent-thickness method to be corrected for the effects of fringing capacitance. Measurements using an unmodified Q-meter system, a VNA-based system, and two other techniques are compared for polyethylene, fused silica, macor and alumina specimens. Good agreement is obtained. The measurements are presented with comprehensive evaluations of uncertainty.

Noise Floor Reduction in Frequency Delta-Sigma Modulation Microphone Sensors.

Frequency delta-sigma modulator (FDSM) employing a variable frequency oscillator is a novel replacement of the classical delta-sigma modulators. This is advantageous for application to sensors, because an ADC can be intrinsically integrated with the sensors. We have already proposed to use this technique to various sensors. However, the signal-to-noise ratio was significantly degraded by noise floor, in the previous papers. In this paper, we have investigated the origin of the noise floor in the FDSM microphone sensors as a promising example. It was demonstrated that improving the phase noise of the oscillator can drastically reduce the noise floor. For this reduction we improved the Q-factor of the cavity resonator, and the design of the oscillator circuit. With these improvements, the phase noise, and, hence, the noise floor, were improved by approximately 40 dB. In addition, we obtained an SNR of 57 dB for 114 dBSPL sound input with 96 kHz bandwidth, which corresponds to the dynamic range of 87 dB for maximum 140 dBSPL. A much larger dynamic range of around 120 dB is expected by increasing the sampling rate and decreasing the Al diaphragm thickness. These results also indicate the promise of the FDSM to varieties of physical sensors.

Germanium-on-silicon waveguides for long-wave integrated photonics: ring resonance and thermo-optics.

Germanium-on-silicon (GOS) represents the leading platform for foundry-based long-wave infrared photonic integrated circuits (LWIR PICs), due to its CMOS compatibility and absence of oxides. We describe ring resonance (Q-factors between 2×103 and 1×104) and thermo-optic tunability in germanium-on-silicon waveguides throughout the long-wave-infrared. The ring resonances are characterized by Q-factors and couplings that agree with measurements of propagation loss (as low as 6 dB/cm) and simulations and are enabled by broadband edge coupling (12dB/facet over a 3 dB bandwidth of over 4 microns). We demonstrate the furthest into the infrared that ring resonators have been measured and show the potential of this platform for photonic integration and waveguide spectroscopy at wavelengths from 7 microns to beyond 11 microns.

A 264-GHz, 2.3-dBm Push–Push Transformer-Based Hartley Oscillator

A high-power subterahertz (THz) push-push oscillator topology is proposed. Adopting Hartley oscillator topology with transformer as its resonator, the proposed oscillator reduces the effective parasitic capacitance of transistors; therefore, a larger size transistor can be adopted, which increases the output power while still maintaining the same oscillation frequency. The adoption of the transformer also improves the LC resonator's Q-factor, further improving the output power and dc-to-RF efficiency. Implemented in 65-nm CMOS technology, the measured output power of the proposed single oscillator is 2.3 dBm at 264 GHz with 2.76% dc-to-RF efficiency and -96.8 dBc/Hz of the phase noise at a 10-MHz offset.

Simulation and Analysis of Microring Electric Field Sensor Based on a Lithium Niobate-on-Insulator

With the increasing sensitivity and accuracy of contemporary high-performance electronic information systems to electromagnetic energy, they are also very vulnerable to be damaged by high-energy electromagnetic fields. In this work, an all-dielectric electromagnetic field sensor is proposed based on a microring resonator structure. The sensor is designed to work at 35 GHz RF field using a lithium niobate-on-insulator (LNOI) material system. The 2.5-D variational finite difference time domain (varFDTD) and finite difference eigenmode (FDE) methods are utilized to analyze the single-mode condition, bending loss, as well as the transmission loss to achieve optimized waveguide dimensions. In order to obtain higher sensitivity, the quality factor (Q-factor) of the microring resonator is optimized to be 106 with the total ring circumference of 3766.59 μm. The lithium niobate layer is adopted in z-cut direction to utilize TM mode in the proposed all-dielectric electric field sensor, and with the help of the periodically poled lithium niobate (PPLN) technology, the electro-optic (EO) tunability of the device is enhanced to 48 pm·μm/V.

Extremely high Q-factor terahertz metasurface using reconstructive coherent mode resonance.

High Q-factor resonance has a pivotal role in wide applications for manipulating electromagnetic waves. However, high Q-factor resonance, especially in the terahertz (THz) regime, has been a challenge faced by plasmonic metamaterials due to the inherent ohmic and radiation losses. Here, we theoretically present a unique metasurface scheme to produce extremely high Q-factor Fano resonance of the reconstructive coherent mode in the THz regime. The THz metasurface is composed of periodically arranged vertical symmetric split ring resonators (SRRs), which can produce perfect reconstructive coherent coupling effect in the sense that dipole radiation is destructively suppressed. Under the polarized electric field perpendicular to SRR gap, the surface currents are out of phase for an individual SRR, leading to the cancellation of net dipole moment. The reconstructive coherent mode resonance can occur between each SRR and its neighboring SRRs, accompanied by destructive interference of the scattered fields of each SRR. This is due to the coupling between the localized resonance of individual particles and the Rayleigh anomaly of the array. The proposed metasurface can significantly suppress far-field radiation and perform an extremely high Q-factor beyond 104 level with large modulation depth in the THz region, which pushes the advancement of THz high Q-factor resonance. The extremely high Q-factor of reconstructive coherent mode is tunable by adjusting the geometry parameters. The design strategy is useful to develop ultra-sensitive sensors, narrow-band filters and strong interaction of field-matter in the THz regime.

Tunable high-Q resonator by general impedance converter.

A tunable high-Q resonator is performed in the schematics of the General Impedance Converter (GIC). In the framework of frequency dependent open-loop gain of operational amplifiers, a general formula of the frequency dependence of the impedance of GIC is derived. The explicit formulas for the resonance frequency and Q-factor include as an immanent parameter the crossover frequency of the operational amplifier. Voltage measurements of GIC with a lock-in amplifier perfectly agree with the derived formulas.

A Low-Complexity Time-Domain Method for a Fast and Accurate Measurement of Q-Factor and Resonant Frequency of RF and Microwave Resonators

A new time-domain technique for an accurate and fast measurement of the resonant frequency and Q-factor of resonators is presented. In this technique, the phase slope with respect to frequency of a resonator is characterized and used to specify its Q-factor and resonant frequency. To measure the phase slope, a slow-rate linear chirp signal is generated and passed through the resonator under test. The output signal is amplified and subsequently divided into two equal parts which are delayed by different amounts. Due to the linear time-frequency relationship of the chirp signal, the instantaneous frequencies of the two delayed signals are slightly different at any given time, and their phase difference can determine the resonator's phase slope. Detailed analysis of the proposed approach is presented and its accuracy is verified through simulations and measurements. Based on the measured results, the proposed approach characterizes the resonant frequency and Q-factor by less than 0.6% and 4% error, respectively.

Method for measuring the Q-factor of miniature open dielectric resonators at ultrahigh frequencies

A simple algorithm for reliably determining the Q-factor of an open dielectric resonator made of a material with a tgδ less than 0.0001 in the shielded region is presented, based on measuring the parameters of an electromagnetically coupled system of bulk metal and open dielectric resonators. The analytical substantiation of the considered method for determining the Q-factor of an open dielectric resonator in electrodynamic and electrotechnical representations is carried out. The variants of the influence of the metal volume on the effective Q-factor of an open dielectric resonator depending on its electrophysical characteristics are considered. The factors affecting the effective Q-factor of an open dielectric resonator obtained using this measurement method are evaluated, and the range of expected measurement errors is shown. The advantage of the method for determining the Q-factor of an open dielectric resonator is the high accuracy of the obtained analytical ratios for determining the Q-factor, the absence of increased requirements for the accuracy of the measurement sections and the quality of the internal surfaces of the metal resonator, the simplicity of the measurement process, based on the use of ordinary equipment and element base.

High-Q Fano Resonance in Subwavelength Stub-Wall-Coupled MDM Waveguide Structure and Its Terahertz Sensing Application

Waveguide structures effectively controlling and guiding terahertz (THz) waves can achieve interesting resonance effects when combined with resonators. At present, achieving high quality factor (Q-factor) resonance in THz resonator-coupled waveguide structure is still a critical consideration to expand its practical application. Here, a high Q-factor Fano resonance based on a metal-dielectric-metal (MDM) waveguide consisting of a stub resonator and a metal wall with an aperture in the center is investigated theoretically and numerically in the THz region. The results show that the sharp and asymmetric Fano resonance peak is induced by the destructive interference between the stub resonator and metal wall which act as a Fabry-Perot cavity. Q-factor is obviously improved about 60 times (3.72 to ~225) by introducing the metal wall into the stub-coupled MDM waveguide. Moreover, Fano resonance can be effectively tuned by varying different structure parameters. Owing to the high sensitivity of Fano resonance peak to dielectric surroundings, a large-range refractive index (RI) sensor based on the proposed structure with a high sensitivity of 96480 nm/RIU is obtained. The figure of merit (FOM) of 195 is greatly improved compared to other THz Fano-based RI sensors. These results provide possibilities for subwavelength MDM waveguide structure to apply for THz bio/chemical sensing, bandpass filters, and on-chip highly integrated plasmonic device.

Polymer Waveguides for Improved Sensitivity in Fiber Fabry-Perot Ultrasound Detectors

This paper presents a fabrication method and results from optical and acoustic characterization of a miniature fiber Fabry-Perot ultrasound detector. A high Q-factor was achieved by creating a self-aligned polymer waveguide within the resonator cavity to restrict diffraction losses. As a result of the improved optical Q-factor upon introduction of the waveguide, a high acoustic sensitivity was achieved. The device presented in this paper demonstrates an optical resonator Q-factor of >2000, and a Noise Equivalent Pressure of 350 Pa over a 25MHz bandwidth on a 125 μm fiber with a 9 μm waveguide. Sensitivity can be further improved significantly with the use of dielectric mirrors. The high sensitivity of these waveguided fiber Fabry-Perot ultrasound detectors makes them suitable for detection of both ultrasound and photoacoustic signals, while their small size makes this technology suitable for adoption in applications requiring small form factor, such as in interventional cardiology.

Magneto-Optical Control of Radiation in Photonic Crystal Structures via the Excitation of Surface Modes

It is shown that the intensity of magneto-optical effects is enhanced by structures containing photonic crystal layers and an iron garnet ferromagnetic dielectric as they support the excitation of quasi-surface Tamm modes at the boundary between the two. Such structures have high Q-factor resonances and can enhance the transverse magneto-optical Kerr effect. Up to 100% magneto-optical modulation can be achieved due to near-surface localization of the electromagnetic field.

Conductivity Extraction Using a 180 GHz Quasi-Optical Resonator for Conductive Thin Film Deposited on Conductive Substrate.

Measurement of electrical conductivity of conductive thin film deposited on a conductive substrate is important and challenging. An effective conductivity model was constructed for a bilayer structure to extract thin film conductivity from the measured Q-factor of a quasi-optical resonator. As a demonstration, aluminium films with thickness of 100 nm were evaporated on four silicon wafers whose conductivity ranges from ~101 to ~105 S/m (thus, the proposed method can be verified for a substrate with a wide range of conductivity). Measurement results at ~180 GHz show that average conductivities are 1.66 × 107 S/m (which agrees well with direct current measurements) with 6% standard deviation. The proposed method provides a contactless conductivity evaluation method for conductive thin film deposited on conductive substrate which cannot be achieved by the existing microwave resonant method.

High quality factor phase gradient metasurfaces.

Dielectric microcavities with quality factors (Q-factors) in the thousands to billions markedly enhance light-matter interactions, with applications spanning high-efficiency on-chip lasing, frequency comb generation and modulation and sensitive molecular detection. However, as the dimensions of dielectric cavities are reduced to subwavelength scales, their resonant modes begin to scatter light into many spatial channels. Such enhanced scattering is a powerful tool for light manipulation, but also leads to high radiative loss rates and commensurately low Q-factors, generally of order ten. Here, we describe and experimentally demonstrate a strategy for the generation of high Q-factor resonances in subwavelength-thick phase gradient metasurfaces. By including subtle structural perturbations in individual metasurface elements, resonances are created that weakly couple free-space light into otherwise bound and spatially localized modes. Our metasurface can achieve Q-factors >2,500 while beam steering light to particular directions. High-Q beam splitters are also demonstrated. With high-Q metasurfaces, the optical transfer function, near-field intensity and resonant line shape can all be rationally designed, providing a foundation for efficient, free-space-reconfigurable and nonlinear nanophotonics.