Waveguiding in two-dimensional piezoelectric phononic crystal plates (original) (raw)
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Absolute band gaps and waveguiding in free standing and supported phononic crystal slabs
Photonics and Nanostructures - Fundamentals and Applications, 2008
Using the finite element method (FEM), we investigate the existence of absolute band gaps and localized modes associated with a guide in thin films of phononic crystals. Two different structures based on two-dimensional (2D) phononic crystals are considered, namely a free standing plate and a plate deposited on a silicon substrate. The 2D phononic crystal is constituted by a square array of cylindrical holes drilled in an active piezoelectric PZT5A matrix. We demonstrate the existence of absolute band gap in the band structure of the phononic crystal plate and, then, the possibility of guided modes inside a linear defect created by removing one row of air holes. In the case of the supported plate, we show the existence of an absolute forbidden band in the plate modes when the thickness of the substrate significantly exceeds the plate thickness. #
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 crystals operating in the gigahertz range with extremely wide band gaps
Applied Physics Letters, 2010
Phononic crystals have numerous potential applications including use as filters and oscillators in communications systems and as acoustic isolators for resonant sensors such as gyroscopes. These applications are based on the ability of phononic crystals to exhibit elastic band gaps, frequency bands where the propagation of acoustic waves is forbidden. Here, we focus on solid-solid phononic crystals ͑solid inclusions in a solid matrix͒, since they typically exhibit wider band gaps than those observed with air-solid phononic crystals ͑air inclusions in a solid matrix͒. We present a micromachined solid-solid phononic crystal operating at 1.4 GHz center frequency with an ultrawide 800 MHz band gap.
Study of an Hybridization Gap in a One Dimensional Piezoelectric Phononic Crystal
Physics Procedia, 2015
A one dimensional Phononic Crystals (PC) composed of a periodic stack including piezoelectric plates is studied. When the size of the pattern is a multiple of the wavelength, Bragg gaps appear based on interference mechanisms. In addition to this property, it is shown in this paper that the use of active piezoelectric plates allows opening hybridization gaps. These gaps are due to a coupling of an electrical resonance with the propagation of the acoustic waves. The electrical resonance is obtained by connecting inductances on the piezoelectric plates. Both experimental and analytical studies are conducted in this paper in order to study this phenomenon. Peer-review under responsibility of the Scientific Committee of 2015 ICU Metz.
In this paper, locally resonant single side column plate phononic crystals are studied. Based on the finite element method, the material properties of the scatterer and the effect of the plate shape on the band gap characteristics of the locally resonant single side column plate phononic crystals are calculated and analyzed by use of the multi-physics software COMSOL. Based on the analysis on the effects of the density, the elastic modulus, the poisson ratio and the shape of the scatterer, it is shown that the density, the elastic modulus and the shape of the scatterer can obviously affect the band gaps of phononiccrystals .
Wave band gaps in two-dimensional piezoelectric/piezomagnetic phononic crystals
International Journal of Solids and Structures
In this paper, the elastic wave propagation in phononic crystals with piezoelectric and piezomagnetic inclusions is investigated taking the magneto-electro-elastic coupling into account. The electric and magnetic fields are approximated as quasi-static. The band structures of three kinds of piezoelectric/piezomagnetic phononic crystals-CoFe 2 O 4 /quartz, BaTiO 3 /CoFe 2 O 4 and BaTiO 3-CoFe 2 O 4 /polymer periodic composites are calculated using the plane-wave expansion method. The piezoelectric and piezomagnetic effects on the band structures are analyzed. The numerical results show that in CoFe 2 O 4 /quartz structures, only one narrow band gap exists along the C-X direction for the coupling of xy-mode and z-mode for the filling fraction f being 0.4; while in BaTiO 3 /CoFe 2 O 4 composites, only one narrow band gap exists along the C-X direction forxy-mode and no band gap exists for z-mode as the filling friction f is 0.5. Moreover, for the new type of magneto-electroelastic phononic crystal-BaTiO 3-CoFe 2 O 4 /polymer periodic composite, the band gap characteristics are more superior in the whole considered frequency regions due to the big contrast of the material properties in the two constituents and the effects of the piezoelectricity and piezomagneticity on the band gap structures are remarkable.
Complete band gaps of phononic crystal plates with square rods
Ultrasonics, 2012
Much of previous work has been devoted in studying complete band gaps for bulk phononic crystal (PC). In this paper, we theoretically investigate the existence and widths of these gaps for PC plates. We focus our attention on steel rods of square cross sectional area embedded in epoxy matrix. The equations for calculating the dispersion relation for square rods in a square or a triangular lattice have been derived. Our analysis is based on super cell plane wave expansion (SC-PWE) method. The influence of inclusions filling factor and plate thickness on the existence and width of the phononic band gaps has been discussed. Our calculations show that there is a certain filling factor (f = 0.55) below which arrangement of square rods in a triangular lattice is superior to the arrangement in a square lattice. A comparison between square and circular cross sectional rods reveals that the former has superior normalized gap width than the latter in case of a square lattice. This situation is switched in case of a triangular lattice. Moreover, a maximum normalized gap width of 0.7 can be achieved for PC plate of square rods embedded in a square lattice and having height 90% of the lattice constant.
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.
Two-dimensional phononic crystal slab defect mode micromechanical resonators
Proceedings of Spie the International Society For Optical Engineering, 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 complimentary-metal- 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.