Europhys. Lett., 76 (3), pp. 422-428 (2006)
DOI: 10.1209/epl/i2006-10277-3

Coherent backscattering of ultrasound without a source

E. Larose, O. I. Lobkis and R. L. Weaver

Department of Theoretical and Applied Mechanics, University of Illinois Urbana, IL 61801, USA

eric.larose@ujf-grenoble.fr

received 29 May 2006; accepted in final form 5 September 2006
published online 22 September 2006

Abstract
Coherent backscattering is due to constructive interferences of reciprocal paths and leads to an enhancement of the intensity of a multiply scattered field near its source. To observe this enhancement an array of receivers is conventionally placed close to the source. Our approach here is different. In a first experiment, we recover the coherent backscattering effect (CBE) within an array of sources and a distant receiver using time correlation of diffuse fields. The enhancement cone has an excellent spatial resolution. The dynamics of the enhancement factor is studied in a second experiment using correlation of thermal phonons at the same ultrasonic frequencies, without any active source.

PACS
43.20.+g - General linear acoustics.
43.35.+d - Ultrasonics, quantum acoustics, and physical effects of sound.
43.40.+s - Structural acoustics and vibration.

© EDP Sciences 2006