Generation of broadband surface acoustic waves using a dual temporal-spatial chirp method

Area of Science:

• Materials Science
• Acoustics
• Physics

Background:

• Surface Acoustic Wave (SAW) generation is crucial for non-destructive testing.
• Conventional impulse excitation for wideband SAW generation is limited by low output amplitudes due to piezoelectric crystal breakdown voltage.
• Optimizing SAW generation is key for accurate characterization of coatings and thin layers.

Purpose of the Study:

• To optimize wideband surface acoustic wave (SAW) generation for non-destructive characterization of coatings and thin layers.
• To overcome the amplitude limitations of impulse excitation in SAW devices.
• To investigate a novel dual temporal-spatial chirp excitation method.

Main Methods:

• Utilized a spatial chirp-based interdigital transducer for SAW generation.
• Compared impulse temporal excitation (Dirac-type pulse) with temporal chirp excitation.
• Investigated the dual temporal-spatial chirp method in the 20 to 125 MHz frequency range.

Main Results:

• Impulse excitation resulted in limited SAW output amplitudes due to breakdown voltage.
• Temporal chirp excitation, matched to the spatial chirp transducer, circumvented these limitations.
• The dual temporal-spatial chirp method achieved higher SAW displacement amplitudes at a lower excitation voltage compared to impulse excitation.

Conclusions:

• The dual temporal-spatial chirp method offers a more efficient approach for wideband SAW generation.
• This technique enhances SAW displacement amplitudes, enabling improved non-destructive testing of thin layers and coatings.
• The findings provide a pathway for more sensitive and reliable material characterization using SAW devices.