Optimization of the Spatial Configuration of Local Defects in Phononic Crystals for High Q Cavity

Defects can be introduced within a 2-D periodic lattice to realize phononic cavities or phononic crystal (PnC) waveguides at the ultrasonic frequency range. The arrangement of these defects within a PnC lattice results in the modification of the Q factor of the cavity or the waveguide. In this work, cavity defects within a PnC formed using cylindrical stainless steel scatterers in water have been modified to control the propagation and Q factor of acoustic waveguides realized through defect channels. The defect channel–based waveguides within the PnC were configured horizontally, vertically, and diagonally along the direction of the propagation of the acoustic waves. Numerical simulations supported by experimental demonstration indicate that the defect-based waveguide’s Q factor is improved by over 15 times for the diagonal configuration compared to the horizontal configuration. It also increases due to an increase in the scatterers’ radius, which was varied from 0.7 to 0.95 mm.

Download Full-text

Periodic Tubular Structures and Phononic Crystals towards High-Q Liquid Ultrasonic Inline Sensors for Pipes

Sensors ◽

10.3390/s21175982 ◽

2021 ◽

Vol 21 (17) ◽

pp. 5982

Author(s):

Nikolay Mukhin ◽

Ralf Lucklum

Keyword(s):

Mode Conversion ◽

Phononic Crystal ◽

Resonant Mode ◽

Phononic Crystals ◽

Acoustic Energy ◽

Wave Radiation ◽

Q Factor ◽

Tubular Structures ◽

High Q ◽

Ultrasound Sensor

The article focuses on a high-resolution ultrasound sensor for real-time monitoring of liquid analytes in cylindrical pipes, tubes, or capillaries. The development of such a sensor faces the challenges of acoustic energy losses, including dissipation at liquid/solid interface and acoustic wave radiation along the pipe. Furthermore, we consider acoustic resonant mode coupling and mode conversion. We show how the concept of phononic crystals can be applied to solve these problems and achieve the maximum theoretically possible Q-factor for resonant ultrasonic sensors. We propose an approach for excitation and measurement of an isolated radial resonant mode with minimal internal losses. The acoustic energy is effectively localized in a narrow probing area due to the introduction of periodically arranged sectioned rings around the tube. We present a sensor design concept, which optimizes the coupling between the tubular resonator and external piezoelectric transducers. We introduce a 2D-phononic crystal in the probing region for this purpose. The Q-factor of the proposed structures show the high prospects for phononic crystal pipe sensors.

Download Full-text

Q-Factor Enhancement of Thin-Film Piezoelectric-on-Silicon MEMS Resonator by Phononic Crystal-Reflector Composite Structure

Micromachines ◽

10.3390/mi11121130 ◽

2020 ◽

Vol 11 (12) ◽

pp. 1130

Author(s):

Jiacheng Liu ◽

Temesgen Bailie Workie ◽

Ting Wu ◽

Zhaohui Wu ◽

Keyuan Gong ◽

...

Keyword(s):

Thin Film ◽

Acoustic Wave ◽

Composite Structure ◽

Phononic Crystal ◽

Q Factor ◽

Leakage Loss ◽

One Dimensional ◽

High Q ◽

Mems Resonator ◽

Mems Resonators

Thin-film piezoelectric-on-silicon (TPoS) microelectromechanical (MEMS) resonators are required to have high Q-factor to offer satisfactory results in their application areas, such as oscillator, filter, and sensors. This paper proposed a phononic crystal (PnC)-reflector composite structure to improve the Q factor of TPoS resonators. A one-dimensional phononic crystal is designed and deployed on the tether aiming to suppress the acoustic leakage loss as the acoustic wave with frequency in the range of the PnC is not able to propagate through it, and a reflector is fixed on the anchoring boundaries to reflect the acoustic wave that lefts from the effect of the PnC. Several 10 MHz TPoS resonators are fabricated and tested from which the Q-factor of the proposed 10 MHz TPoS resonator which has PnC-reflector composite structure on the tether and anchoring boundaries achieved offers a loaded Q-factor of 4682 which is about a threefold improvement compared to that of the conventional resonator which is about 1570.

Download Full-text

GHz Heterogeneous Phononic Crystal Slab Resonators

Volume 13: Vibration, Acoustics and Wave Propagation ◽

10.1115/imece2015-52765 ◽

2015 ◽

Author(s):

Razi Dehghannasiri ◽

Reza Pourabolghasem ◽

Ali Asghar Eftekhar ◽

Ali Adibi

Keyword(s):

Wireless Communications ◽

High Frequency ◽

Phononic Crystal ◽

Smooth Transition ◽

Frequency Range ◽

High Q ◽

Guided Modes

In this paper, we present a new design for waveguide-based phononic crystal (PnC) resonators in pillar-based piezoelectric membranes at the GHz frequency range based on mode-gap waveguide termination. The mode confinement in these resonators is achieved by a smooth transition from a phononic waveguide to another phononic waveguide that does not support (and therefore reflects) the guided modes of the first waveguide over a certain frequency range. These resonators can be utilized for applications including wireless communications and sensing [1, 2] where high-Q and high-frequency resonators are highly desirable.

Download Full-text

Bandgaps characteristics of the periodical slit metal tubes with backstraps

International Journal of Modern Physics B ◽

10.1142/s0217979217501259 ◽

2017 ◽

Vol 31 (15) ◽

pp. 1750125 ◽

Cited By ~ 1

Author(s):

Kai Bao ◽

Tianning Chen ◽

Xiaopeng Wang ◽

Ailing Song ◽

Lele Wan

Keyword(s):

Acoustic Waves ◽

Mass Density ◽

Phononic Crystal ◽

Location Parameter ◽

Slit Width ◽

The Finite Element Method ◽

Frequency Range ◽

Transmission Coefficients ◽

Helmholtz Resonators ◽

Location Parameters

In this paper, a new two-dimensional (2D) phononic crystal structure composed of periodic slit metal tubes, in which the unit cell consists of straight or curved backstraps, is proposed, and the propagation characteristics of acoustic waves in this structure are theoretically investigated. Using the finite-element method, we calculate the dispersion relations and transmission coefficients of this structure. The results show that, in contrast to the only slit metal tubes, the periodic slit metal tubes with straight or curved backstraps are proved to display band gaps (BGs) at much lower frequency range. Meanwhile, the effect of the slit width of the backstraps on the BGs is investigated. The results show that the positions and widths of the BGs can be effectively modulated by the backstraps without changing the mass density or lattice constant of the material. The lowest frequency falls by about 200 Hz. Moreover, we investigated how the BGs are affected by the location parameter of the backstraps, finding that the acoustic BGs are sensitive to the location parameter of the backstraps. Numerical results show that BGs are significantly dependent upon the slit width and location parameters of the backstraps. The BGs are optimized because, the effect of the Helmholtz resonators of the slit tube is strengthened and changed when the location and slit width of the backstraps change. These results provide a good reference for optimizing BGs, generating filters and designing devices.

Download Full-text

Characterization of fractured low Q zones at the Buena Vista Hills reservoir, California

Geophysics ◽

10.1190/1.1500366 ◽

2002 ◽

Vol 67 (4) ◽

pp. 1061-1070 ◽

Cited By ~ 7

Author(s):

Jorge O. Parra ◽

Chris L. Hackert ◽

Pei‐Cheng Xu

Keyword(s):

Fluid Flow ◽

Acoustic Waves ◽

Dispersion Analysis ◽

Q Factor ◽

Frequency Range ◽

Fracture Permeability ◽

Buena Vista ◽

Flow Length ◽

Principal Axes ◽

Siliceous Shale

We show that attenuation of high‐resolution interwell seismic and acoustic waves based on velocity dispersion analysis relates to fluid‐flow effects in fractured and shale–sand sequence formations at the Buena Vista Hills reservoir, California. Fractured low quality factor (Q‐factor) zones in the Brown Shale and Antelope Shale reservoir intervals in the Monterrey Formation correlate with a system of fractures having permeabilities of 2.5 to 5 md. Vertical fractures oriented at azimuths from 0° to 30° are detected in the frequency range of 1 to 10 kHz. We establish that a poroelastic model based on the Biot/squirt‐flow (BISQ) mechanism can be used to relate the low Q‐factor zones in the Brown and Antelope Shales. Because the Brown Shale has no sands, we use it to evaluate a fracture system's response to attenuation. We adapt the BISQ mechanism to simulate fluid flow in fracture‐induced anisotropy, which provides flow properties parallel and perpendicular to fractures in the siliceous shale formations. The model assumes that the principal axes of the stiffness tensor are aligned with the axes of the permeability and squirt‐flow tensors. We simulate the fracture system by assuming that (1) a squirt‐flow length on the order of centimeters represents fluid flow in fractures and (2) a squirt‐flow length <1 mm represents flow in low‐permeability shales. Two types of fractures at the site are joint‐like tectonic fractures and sigmoidal vein fractures. Their fracture permeability (approximately 5 md) and squirt‐flow lengths (between 1 and 2 cm) predict a Q‐factor of about 20 that fits the observed Q‐factor in the Brown Shale. We find that fractures associated with squirt‐flow lengths ≥3 cm are sensitive to horizontal attenuation for a frequency range of 120 to 1000 Hz. In addition, the horizontal Q‐factor derived from sonic and crosswell data is about five times less than the vertical Q‐factor associated with waves originating from the earth's surface.

Download Full-text

High-Q-Factor Tunable Silica-Based Microring Resonators

Photonics ◽

10.3390/photonics8070256 ◽

2021 ◽

Vol 8 (7) ◽

pp. 256

Author(s):

Yue-Xin Yin ◽

Xiao-Pei Zhang ◽

Xiao-Jie Yin ◽

Yue Li ◽

Xin-Ru Xu ◽

...

Keyword(s):

Optical Communications ◽

Microring Resonator ◽

Microring Resonators ◽

Q Factor ◽

Notch Depth ◽

Critical Coupling ◽

Practical Application ◽

Coupling Condition ◽

High Q ◽

Racetrack Resonator

A high-Q-factor tunable silica-based microring resonator (MRR) is demonstrated. To meet the critical-coupling condition, a Mach–Zehnder interferometer (MZI) as the tunable coupler was integrated with a racetrack resonator. Then, 40 mW electronic power was applied on the microheater on the arm of MZI, and a maximal notch depth of about 13.84 dB and a loaded Q factor of 4.47 × 106 were obtained. The proposed MRR shows great potential in practical application for optical communications and integrated optics.

Download Full-text

Dielectric-loaded L-band filters for high-power space applications

International Journal of Microwave and Wireless Technologies ◽

10.1017/s1759078721000982 ◽

2021 ◽

pp. 1-11

Author(s):

Paolo Vallerotonda ◽

Fabrizio Cacciamani ◽

Luca Pelliccia ◽

Alessandro Cazzorla ◽

Davide Tiradossi ◽

...

Keyword(s):

High Power ◽

Dielectric Resonators ◽

Q Factor ◽

Rf Power ◽

Space Applications ◽

High Q ◽

Critical Issues ◽

L Band ◽

Multipactor Discharge ◽

Filter Response

Abstract The design and first experimental results of Tx and Rx L-band bandpass filters for a high-power satellite diplexer are presented in this paper. Designed in the framework of an ESA ARTES AT project, the filters are based on TM010 mode dielectric resonators. These resonators allow for better results in terms of volume occupation with respect to other dielectric resonators still maintaining high Q-factor values (>2000). Volume saving above 30% is achieved with respect to standard coaxial filters. The filter geometries and materials have been chosen in order to improve the power-handling and to cope with related critical issues for space applications (i.e. avoid any multipactor discharge in the operating RF power range and low-PIM response). Measurements of Tx filter show good correlation with the design in terms of central frequency, BW, and unloaded Q-factor (almost 3000). Measurements of Rx filter show a worse correlation with the design in terms of filter response shape. This is ascribed to size tolerances of one of the filter resonators. Multiple analyses are ongoing to remove this degradation in the final engineering model.

Download Full-text