Complete bandgap SAW phononic resonant topologies (original) (raw)
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Complete bandgap SAW phononic resonators
2014 European Frequency and Time Forum (EFTF), 2014
2D composite grating building blocks with hexagonal symmetry are proposed as efficient reflectors and transducers in the design of surface acoustic wave (SAW) resonators. Design parameters ensuring complete bandgap characteristics are deduced by means of finite element analysis (FEA). SAW resonators employing phononic building blocks with complete bandgaps are designed, fabricated and tested. Further, the influence of the phononic grating over the spurious responses and the busbar quality are experimentally tested. All test structures are fabricated on 128 Y-X LiNbO 3 using low resolution optical lithography and standard metal deposition and etching routines.
Study of surface acoustic waves under periodic grating structures
Proceedings of the 7th WSEAS …, 2008
The propagation characteristics of the surface acoustic waves (SAW) propagating under the periodic metal grating on ST-cut quartz substrates were theoretically investigated in order to achieve more accurate design of the devices. The theoretical method used ...
A surface acoustic resonator with template-patterned interdigitated fingers
Sensors and Actuators A: Physical, 2016
Printed electronics techniques show promise as high-throughput, low-cost methods for fabricating micro-scale device features. In this work, we demonstrate a SAW resonator fabricated through a printing process. Silver nanoparticle ink is introduced to a vapor-permeable template that is patterned with the desired SAW resonator metallization. After the solvent in the ink evaporates, the nanoparticles within the patterned template tightly pack to form the device metallization. Interdigitated resonator electrodes with widths and spacing ranging from 500 nm to 1 m were patterned on lithium niobate, corresponding to center frequencies of 2.1-2.4 GHz. The maximum quality factor was 13. Limitations and potential process improvements are discussed to improve resonator quality factor in future work.
Advances in Applied Sciences, 2019
The emergence of acoustic metamaterials generated a lot of attention in the study of low-frequency vibration, noise control and reduction in engineering applications. As a result, the elastic wave bandgap characteristics of a two-dimensional microcavity local resonator structure for two soft rubber materials was investigated using finite element methods (FEM). The transmission spectrum of the displacement eigenmodes of the bandgap edges relating to the lowest bandgap was calculated. The results showed that the phononic crystal structure without a microcavity local resonator plate has bandgap characteristics of elastic wave propagation in the high-frequency range between 2200~2400Hz. However, with the introduction of microcavity resonator plates in the phononic crystal structure low-frequency bandgaps are obtained in the region of 0~198Hz and 0~200Hz respectively. The low-frequency bandgaps appeared as a result of the microcavity local resonator plate which increased the path length through which the wave is transmitted. The phononic crystal microcavity local resonator plate structure has varying transmission loss characteristics of-65dB,-85dB,-100dB and-150dB in the low-frequency range depending on the number of local resonator plates introduced into the cell structure and density of the cell structure. The study provided a good demonstration of wave propagation in artificially engineered materials with critical emphasis on the effects of local resonators in a microcavity structure.
Research on micro-sized acoustic bandgap structures
2010
Phononic crystals (or acoustic crystals) are the acoustic wave analogue of photonic crystals. Here a periodic array of scattering inclusions located in a homogeneous host material forbids certain ranges of acoustic frequencies from existence within the crystal, t hus creating what are known as acoustic (or phononic) bandgaps. The vast majority of phononic crystal devices reported prior to this LDRD were constructed by hand assembling scattering inclusions in a lossy viscoelastic medium, predominantly air, water or epoxy, resulting in large structures limited to frequencies below 1 MHz. Under this LDRD, phononic crystals and devices were scaled to very (VHF: 30-300 MHz) and ultra (UHF: 300-3000 MHz) high frequencies utilizing finite difference time domain (FDTD) mo deling, microfabrication and micromachining technologies. This LDRD developed key breakthroughs in the areas of micro-phononic crystals including physical origins of phononic crystals, advanced FDTD modeling and design techniques, material co nsiderations, microfabrication processes, characterization methods and device structures. Micro-phononic crystal devices realized in low-loss solid materials were emphasized in this work due to their potential applications in radio frequency co mmunications and acoustic imaging for medical ultrasound and nondestructive testing. The results of the advanced modeling, fabrication and integrated transducer designs were t hat this LDRD produced the 1 st measured phononic crystals and phononic crystal devices (waveguides) operating in the VHF (67 MHz) and UHF (937 MHz) frequency bands and est ablished Sandia as a world leader in the area of micro-phononic crystals.
From phononic crystals to SAW devices
We investigate the possibility of obtaining phononic crystals using materials commonly employed in device microfabrication. This study gathers the latest research on micro-phonon crystals, design techniques, material considerations, microfabrication processes, characterization methods and reported devices. Particularly are highlighted the advantages of these crystals in SAW device structures and theirs micro fabrication processes. We focus our attention to theoretical method of waves propagations in two-dimensional phononic crystals made of cylindrical holes drilled in an active piezoelectric matrix. First numerical results for the simulation of propagation of acoustic waves in a SAW device with phononic crystals are obtained by our work group. The present work provides evidences that these phononic crystals can be using in microdevices and increases the performances of SAW devices.
Evidence for complete surface wave band gap in a piezoelectric phononic crystal
Physical Review E, 2006
A complete surface acoustic wave band gap is found experimentally in a two-dimensional square-lattice piezoelectric phononic crystal etched in lithium niobate. Propagation in the phononic crystal is studied by direct generation and detection of surface waves using interdigital transducers. The complete band gap extends from 203 to 226 MHz, in good agreement with theoretical predictions. Near the upper edge of the complete band gap, it is observed that radiation to the bulk of the substrate dominates. This observation is explained by introducing the concept of the sound line.
Phononic crystal diffraction gratings
Journal of Applied Physics, 2012
When a phononic crystal is interrogated by an external source of acoustic waves, there is necessarily a phenomenon of diffraction occurring on the external enclosing surfaces. Indeed, these external surfaces are periodic and the resulting acoustic diffraction grating has a periodicity that depends on the orientation of the phononic crystal. This work presents a combined experimental and theoretical study on the diffraction of bulk ultrasonic waves on the external surfaces of a 2D phononic crystal that consists of a triangular lattice of steel rods in a water matrix. The results of transmission experiments are compared with theoretical band structures obtained with the finite-element method. Angular spectrograms (showing frequency as a function of angle) determined from diffraction experiments are then compared with finite-element simulations of diffraction occurring on the surfaces of the crystal. The experimental results show that the diffraction that occurs on its external surfaces is highly frequency-dependent and has a definite relation with the Bloch modes of the phononic crystal. In particular, a strong influence of the presence of bandgaps and deaf bands on the diffraction efficiency is found. This observation opens perspectives for the design of efficient phononic crystal diffraction gratings. V
Two-dimensional phononic crystal slab defect mode micromechanical resonators
Photonic and Phononic Crystal Materials and Devices IX, 2009
By creating line defects cavities in the structure of a phononic crystal (PC) made by etching a hexagonal (honeycomb) array of holes in a 15µm-thick slab of silicon, high-Q PC resonators are fabricated and tested using a complimentarymetal-oxide-semiconductor-compatible process. The radii of the holes are approximately 6.4µm and the spacing between nearest holes is 15µm. We show that the complete phononic band gap of the PC structure supports resonant modes with quality factors of more than 6000 at frequencies as high as 126MHz in the resonator structure. The very good confinement of acoustic energy is achieved by using only a few PC layers confining the cavity region. The calculated frequencies of resonance of the structure using finite element method are in a very good agreement with the experimental data. The performance of these PC resonator structures makes them excellent candidates for wireless communication and sensing applications.
Journal of Applied Physics, 2014
We study both theoretically and experimentally the interaction of surface elastic waves with 2D surface phononic crystal (PnC) on a piezoelectric substrate. A rigorous analysis based on 3D finite element method is conducted to calculate the band structure of the PnC and to analyze the transmission spectrum (module and phase). Interdigital transducers (IDTs) are considered for electrical excitation and detection, and absorbing boundary conditions are used to suppress wave's reflection from the edges. The PnCs are composed of an array of 20 Nickel cylindrical pillars arranged in a square lattice symmetry, and deposited on a LiNbO 3 substrate (128 Y cut-X propagating) between two dispersive IDTs. We investigate by means of band diagrams and transmission spectrum the opening band-gaps originating from pillars resonant modes and from Bragg band-gap. The physical parameters that influence and determine their appearance are also discussed. Experimental validation is achieved through electrical measurement of the transmission characteristics, including amplitude and phase. V