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Laser-interferometric analysis of surface acoustic wave resonators

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Knuuttila, Jouni
dc.date.accessioned 2012-02-17T07:03:18Z
dc.date.available 2012-02-17T07:03:18Z
dc.date.issued 2005-06-03
dc.identifier.isbn 951-22-7699-2
dc.identifier.issn 1459-7268
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/2579
dc.description.abstract The 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.format.extent 45, [app]
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Helsinki University of Technology en
dc.publisher Teknillinen korkeakoulu fi
dc.relation.ispartofseries Helsinki University of Technology publications in engineering physics. A en
dc.relation.ispartofseries Teknillisen korkeakoulun teknillisen fysiikan julkaisuja. A fi
dc.relation.ispartofseries 838 en
dc.relation.haspart J. 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.haspart J. 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.haspart J. 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.haspart T. 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.haspart J. 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.haspart J. 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.haspart J. 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.subject.other Physics en
dc.title Laser-interferometric analysis of surface acoustic wave resonators en
dc.type G5 Artikkeliväitöskirja fi
dc.description.version reviewed en
dc.contributor.department Department of Engineering Physics and Mathematics en
dc.contributor.department Teknillisen fysiikan ja matematiikan osasto fi
dc.subject.keyword leaky surface acoustic waves en
dc.subject.keyword bulk acoustic waves en
dc.subject.keyword LSAW resonator en
dc.subject.keyword laser interferometry en
dc.subject.keyword acoustic losses en
dc.identifier.urn urn:nbn:fi:tkk-005339
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en
dc.contributor.lab Materials Physics Laboratory en
dc.contributor.lab Materiaalifysiikan laboratorio fi
local.aalto.digifolder Aalto_68518
local.aalto.digiauth ask


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