Laser-interferometric analysis of surface acoustic wave resonators

dc.contributorAalto-yliopistofi
dc.contributorAalto Universityen
dc.contributor.authorKnuuttila, Jouni
dc.contributor.departmentDepartment of Engineering Physics and Mathematicsen
dc.contributor.departmentTeknillisen fysiikan ja matematiikan osastofi
dc.contributor.labMaterials Physics Laboratoryen
dc.contributor.labMateriaalifysiikan laboratoriofi
dc.date.accessioned2012-02-17T07:03:18Z
dc.date.available2012-02-17T07:03:18Z
dc.date.issued2005-06-03
dc.description.abstractThe research work described in this Thesis concentrates on studying surface acoustic wave (SAW) resonators, in particular resonators which utilize the leaky surface acoustic wave (LSAW) mode. Such resonators constitute building blocks for radio-frequency SAW bandpass filters, which are widely employed in modern cordless and cellular telecommunication systems. The number of radio frequency SAW filters produced presently exceeds 3 billion per year. The work is carried out with an optical Michelson laser interferometer developed at the Materials Physics Laboratory specifically for the purpose of studying SAW components. In the course of this work the interferometer was equipped with a high-speed photodetector and state-of-the-art detection electronics, enabling the measurement of surface vibrations at frequencies as high as 2 GHz with amplitudes on the order of a few picometers. Furthermore, the setup was equipped with high-precision motorized scanning stages and computer control in order to facilitate automatically performed two-dimensional scans with a large number of scanning points and measuring speeds up to 50 000 points per hour. The optical setup features a spatial resolution better than one micrometer, enabling measurement of surface waves with wavelengths down to 2 micrometers. The interferometer can be used for analysis of surface acoustic wave devices as well as for thin-film bulk acoustic wave resonators and radio-frequency microelectromechanical systems (RF-MEMS). Laser-interferometric measurements were performed on LSAW resonators and filters on rotated Y-cut lithium tantalate (LiTaO3). As a result, an unexpected acoustic field distribution was observed. Further measurements and simulations showed that the observed field distributions resulted from LSAWs escaping outside the resonator into the busbars. This acoustic loss mechanism can significantly degrade the performance of an LSAW filter. The obtained results have been acknowledged by SAW filter manufacturers in Japan and in Europe. In addition, measurements of bulk acoustic wave (BAW) radiation from LSAW resonators were carried out. Such radiation is inherent for LSAW resonators. Theoretical models and numerical simulations characterizing the phenomenon exist but very few direct measurements have been reported. Here, direct measurement results of BAW radiation fields generated by an LSAW resonator on LiTaO3 are reported revealing both fast shear and slow shear bulk waves. Furthermore, two coupling mechanisms, backscattering and direct excitation, were identified. Such information can be used in the development of more accurate simulation models.en
dc.description.versionrevieweden
dc.format.extent45, [app]
dc.format.mimetypeapplication/pdf
dc.identifier.isbn951-22-7699-2
dc.identifier.issn1459-7268
dc.identifier.urihttps://aaltodoc.aalto.fi/handle/123456789/2579
dc.identifier.urnurn:nbn:fi:tkk-005339
dc.language.isoenen
dc.publisherHelsinki University of Technologyen
dc.publisherTeknillinen korkeakoulufi
dc.relation.haspartJ. V. Knuuttila, P. T. Tikka, and M. M. Salomaa. 2000. Scanning Michelson interferometer for imaging surface acoustic wave fields. Optics Letters 25, pages 613-615. [article1.pdf] © 2000 Optical Society of America (OSA). By permission.
dc.relation.haspartJ. V. Knuuttila, P. T. Tikka, C. S. Hartmann, V. P. Plessky, and M. M. Salomaa. 1999. Anomalous asymmetric acoustic radiation in low-loss SAW filters. Electronics Letters 35, pages 1115-1116. [article2.pdf] © 1999 IEE. By permission.
dc.relation.haspartJ. Koskela, J. V. Knuuttila, P. T. Tikka, C. S. Hartmann, V. P. Plessky, and M. M. Salomaa. 1999. Mechanism for acoustic leakage in surface-acoustic wave resonators on rotated Y-cut lithium tantalate substrate. Applied Physics Letters 75, pages 2683-2685. [article3.pdf] © 1999 American Institute of Physics. By permission.
dc.relation.haspartT. Makkonen, S. Kondratiev, V. P. Plessky, T. Thorvaldsson, J. Koskela, J. V. Knuuttila, and M. M. Salomaa. 2001. Surface acoustic wave impedance element ISM duplexer: modeling and optical analysis. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 48, pages 652-665. [article4.pdf] © 2001 IEEE. By permission.
dc.relation.haspartJ. Koskela, J. V. Knuuttila, T. Makkonen, V. P. Plessky, and M. M. Salomaa. 2001. Acoustic loss mechanisms in leaky SAW resonators on lithium tantalate. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 48, pages 1517-1526. [article5.pdf] © 2001 IEEE. By permission.
dc.relation.haspartJ. V. Knuuttila, J. Saarinen, C. S. Hartmann, V. P. Plessky, and M. M. Salomaa. 2001. Measurement of BAW radiation from low-loss LSAW resonators. Electronics Letters 37, pages 1055-1056. [article6.pdf] © 2001 IEE. By permission.
dc.relation.haspartJ. V. Knuuttila, J. J. Vartiainen, J. Koskela, V. P. Plessky, C. S. Hartmann, and M. M. Salomaa. 2004. Bulk-acoustic waves radiated from low-loss surface-acoustic-wave resonators. Applied Physics Letters 84, pages 1579-1581. [article7.pdf] © 2004 American Institute of Physics. By permission.
dc.relation.ispartofseriesHelsinki University of Technology publications in engineering physics. Aen
dc.relation.ispartofseriesTeknillisen korkeakoulun teknillisen fysiikan julkaisuja. Afi
dc.relation.ispartofseries838en
dc.subject.keywordleaky surface acoustic wavesen
dc.subject.keywordbulk acoustic wavesen
dc.subject.keywordLSAW resonatoren
dc.subject.keywordlaser interferometryen
dc.subject.keywordacoustic lossesen
dc.subject.otherPhysicsen
dc.titleLaser-interferometric analysis of surface acoustic wave resonatorsen
dc.typeG5 Artikkeliväitöskirjafi
dc.type.dcmitypetexten
dc.type.ontasotVäitöskirja (artikkeli)fi
dc.type.ontasotDoctoral dissertation (article-based)en
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