Focusing of sound in a 3D phononic crystal.
We present a combined experimental and theoretical study of phonon focusing phenomena in a pass band above the complete band gap in a 3D phononic crystal. Wave propagation was found to depend dramatically on both frequency and incident direction. This propagation anisotropy leads to very large negative refraction, which can be used to focus a diverging ultrasonic beam into a narrow focal spot with a large focal depth. The experimental field patterns are well explained using a Fourier imaging technique, based on the 3D equifrequency surfaces calculated from multiple scattering theory.
Yang
Suxia
S
Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
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J H
JH
Liu
Zhengyou
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Cowan
M L
ML
Chan
C T
CT
Sheng
Ping
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