Multilayer transducer for highly efficient initiation of time-resolved Brillouin scattering

Structures made of a metallic film deposited on a substrate are conventionally used as opto-acoustic transducers for picosecond ultrasonic experiments where detection in the time domain of the Brillouin scattering in a transparent sample is sought. In this paper, we substitute the metallic film for...

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Bibliographic Details
Published in:Applied physics letters 2022-05, Vol.120 (21)
Main Authors: Bruno, François, Saint-Martin, Loïc, Thuau, Damien, Audoin, Bertrand
Format: Article
Language:English
Subjects:
Amplification
Applied physics
Composite structures
Engineering Sciences
Frequency shift
Gold
Lithium
Lithium fluoride
Mechanics
Multilayers
Scattering
Substrates
Temperature effects
Thickness
Transducers
Ultrasonic testing
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Summary:Structures made of a metallic film deposited on a substrate are conventionally used as opto-acoustic transducers for picosecond ultrasonic experiments where detection in the time domain of the Brillouin scattering in a transparent sample is sought. In this paper, we substitute the metallic film for a periodic stack of nanometric layers made of gold and lithium fluoride to increase the amplitude, at the Brillouin frequency shift, of the strain generated by the photo-thermal effect. A model is used to analyze the generated strain amplification with the volume fraction and with the total thickness of this structure and to evaluate the gain in terms of sample dynamic reflectivity changes. Amplification by a factor of 20 is measured when using the composite structure with respect to signals detected with a transducer made of a single gold layer.
ISSN:0003-6951
1077-3118
DOI:10.1063/5.0092113