DocumentCode :
1218248
Title :
Phases of the SAW reflection and transmission coefficients for short reflectors on 128/spl deg/ LiNbO/sub 3/
Author :
Lehtonen, Saku ; Plessky, Victor P. ; Béreux, Natacha ; Salomaa, Martti M.
Author_Institution :
Mater. Phys. Lab., Helsinki Univ. of Technol., Finland
Volume :
51
Issue :
12
fYear :
2004
Firstpage :
1671
Lastpage :
1682
Abstract :
We study numerically the phase of surface acoustic waves reflected by or transmitted through short reflectors comprising only 1-3 aluminium electrodes on 128/spl deg/ YX-cut lithium niobate (LiNbO/sub 3/). The electrodes have a finite thickness, and they are either open-circuited or grounded. The center-to-center distance between adjacent electrodes d corresponds roughly either to half of the characteristic wavelength d/spl prop//spl lambda//sub 0//2 or to d/spl prop//spl lambda//sub 0/, for the reflectors operating at the fundamental and second harmonic modes, respectively. We use software based on the finite-element and boundary-element methods (FEM/BEM) for numerical experiments with a tailored test structure having 3 interdigital transducers (IDTs), simulating experimental conditions with an incident wave and reflected and transmitted surface acoustic wave (SAW). Using artificial enhancement of time resolution in conjunction with the fast Fourier transform (FFT) and time-gating, calculation of the Y-parameters in a relatively wide frequency range allows us to determine the phase of the reflection and transmission coefficients.
Keywords :
aluminium; boundary-elements methods; electrodes; fast Fourier transforms; finite element analysis; lithium compounds; surface acoustic wave devices; surface acoustic waves; Al; BEM; FEM; FFT; IDT; LiNbO/sub 3/; SAW; Y-parameters; YX cut lithium niobate; aluminium electrodes; boundary element methods; fast Fourier transform; finite element methods; fundamental harmonic modes; incident wave surface acoustic wave; interdigital transducers; reflected surface acoustic wave; second harmonic modes; short reflectors; surface acoustic waves reflection coefficients; surface acoustic waves transmission coefficients; tailored test structure; time gating calculation; transmitted surface acoustic wave; Acoustic reflection; Acoustic testing; Acoustic waves; Aluminum; Electrodes; Finite element methods; Lithium niobate; Rough surfaces; Surface acoustic waves; Surface roughness;
fLanguage :
English
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
Publisher :
ieee
ISSN :
0885-3010
Type :
jour
DOI :
10.1109/TUFFC.2004.1386684
Filename :
1386684
Link To Document :
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