Ultrasonic subwavelength phase conjugated mirror with a layer of bubbles.
A single layer of gas bubbles in a yield-stress fluid is experimentally shown to behave as a phase-conjugated (PC) mirror with a thickness 250 times smaller than the wavelength (0.14mm-diameter bubbles for phase-conjugation at 40kHz). A high amplitude pump wave at frequency 80kHz interacts with a lower amplitude probe wave centered at 40kHz. A PC-reflection coefficient of 0.15 is obtained for a 50kPa pump. A perturbative second-order theory is shown to quantitatively describe the experimental observations.
Laboratoire Matière et Systèmes Complexes, Universitè Paris-Diderot, CNRS (UMR 7057), Paris, France. Electronic address: olivier.lombard@univ-amu.fr.
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Lombard
Institut Langevin, ESPCI ParisTech, CNRS (UMR 7587), PSL Research University, Paris, France.
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Barrière
Laboratoire Matière et Systèmes Complexes, Universitè Paris-Diderot, CNRS (UMR 7057), Paris, France.
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Leroy
Bubbly medium; Nonlinear acoustics; Phase conjugation