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Title: Lamb Wave Focusing Transducer for Efficient Coupling to Wavelength-Scale Structures in Thin Piezoelectric Films

Abstract

This study describes the theoretical and experimental investigation of interdigitated transducers (IDTs) capable of producing focused acoustical beams in thin film piezo-electric materials. A mathematical formalism describing focused acoustical beams, Lamb beams, is presented and related to their optical counterparts in two- and three-dimensions. A novel Fourier domain transducer design methodology was developed and utilized to produce near diffraction limited focused beams with in a thin film AlN membrane. The properties of the acoustic beam formed by the transducer were studied by means of Doppler vibrometry implemented with a scanning confocal balanced homodyne interferometer. Fourier domain modal analysis confirmed that 85% of the acoustical power was delivered to the targeted focused beam which was constituted from the lowest order symmetric mode, while 2% was delivered unintentionally to the beam formed from the anti-symmetric mode, and the remaining power was isotropically scattered. The transmission properties of the acoustic beams as they interact with devices with wavelength scale features were also studied, demonstrating minimal insertion loss for devices in which a subwavelength, pinhole apertures was included.

Authors:
ORCiD logo [1];  [2];  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Defense Advanced Research Project Agency, Arlington, VA (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1452667
Report Number(s):
SAND-2018-2363J
Journal ID: ISSN 1057-7157; 661166
Grant/Contract Number:  
AC04-94AL85000
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Microelectromechanical Systems
Additional Journal Information:
Journal Name: Journal of Microelectromechanical Systems; Journal ID: ISSN 1057-7157
Publisher:
IEEE
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Aluminum nitride; acoustic focusing; Lamb wave transducers; Doppler vibrometry

Citation Formats

Siddiqui, Aleem, Olsson, Roy H., and Eichenfield, Matt. Lamb Wave Focusing Transducer for Efficient Coupling to Wavelength-Scale Structures in Thin Piezoelectric Films. United States: N. p., 2018. Web. doi:10.1109/JMEMS.2018.2865855.
Siddiqui, Aleem, Olsson, Roy H., & Eichenfield, Matt. Lamb Wave Focusing Transducer for Efficient Coupling to Wavelength-Scale Structures in Thin Piezoelectric Films. United States. doi:10.1109/JMEMS.2018.2865855.
Siddiqui, Aleem, Olsson, Roy H., and Eichenfield, Matt. Thu . "Lamb Wave Focusing Transducer for Efficient Coupling to Wavelength-Scale Structures in Thin Piezoelectric Films". United States. doi:10.1109/JMEMS.2018.2865855. https://www.osti.gov/servlets/purl/1452667.
@article{osti_1452667,
title = {Lamb Wave Focusing Transducer for Efficient Coupling to Wavelength-Scale Structures in Thin Piezoelectric Films},
author = {Siddiqui, Aleem and Olsson, Roy H. and Eichenfield, Matt},
abstractNote = {This study describes the theoretical and experimental investigation of interdigitated transducers (IDTs) capable of producing focused acoustical beams in thin film piezo-electric materials. A mathematical formalism describing focused acoustical beams, Lamb beams, is presented and related to their optical counterparts in two- and three-dimensions. A novel Fourier domain transducer design methodology was developed and utilized to produce near diffraction limited focused beams with in a thin film AlN membrane. The properties of the acoustic beam formed by the transducer were studied by means of Doppler vibrometry implemented with a scanning confocal balanced homodyne interferometer. Fourier domain modal analysis confirmed that 85% of the acoustical power was delivered to the targeted focused beam which was constituted from the lowest order symmetric mode, while 2% was delivered unintentionally to the beam formed from the anti-symmetric mode, and the remaining power was isotropically scattered. The transmission properties of the acoustic beams as they interact with devices with wavelength scale features were also studied, demonstrating minimal insertion loss for devices in which a subwavelength, pinhole apertures was included.},
doi = {10.1109/JMEMS.2018.2865855},
journal = {Journal of Microelectromechanical Systems},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {9}
}

Journal Article:
Free Publicly Available Full Text
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Cited by: 2 works
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Figures / Tables:

Figure 1 Figure 1: Illustration of the typical problem encountered with large transducers trying to excite wavelength-scale structures. The wave produced by the send transducer suffers an insertion loss at the waveguide input of approximately the ratio of the width of the waveguide to the width of the transducer. Intercepting the wavemore » immediately at the waveguide output produces a second, symmetric insertion loss. If the transducer is offset from the waveguide output (as shown), diffraction expands the beam but causes wave front curvature that will tend to average the received signal to zero.« less

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