Time reversal of ultrasound through a phononic crystal.

In this Letter, we experimentally investigate time reversal focusing through a phononic crystal consisting of a periodic square arrangement of steel rods in water. An acoustic pulse is transmitted through the medium, received at a transducer array, time reversed and backpropagated. Both spatial focusing and time compression are studied and compared with those obtained through an equivalent disordered medium. With the phononic crystal, we do not observe the "hyperfocusing effect" that is typical of time reversal through disordered samples.

[1]  J. Aragón,et al.  Quasiperiodic Bloch-like states in a surface-wave experiment. , 2002, Physical review letters.

[2]  Ultrasonic wedges for elastic wave bending and splitting without requiring a full band gap. , 2001, Physical review letters.

[3]  M. Fink,et al.  Time-reversal of ultrasonic fields. III. Theory of the closed time-reversal cavity , 1992, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[4]  Hongkai Zhao,et al.  Super-resolution in time-reversal acoustics. , 2002, The Journal of the Acoustical Society of America.

[5]  B. Djafari-Rouhani,et al.  Acoustic band structure of periodic elastic composites. , 1993, Physical review letters.

[6]  P A Deymier,et al.  Experimental and theoretical evidence for the existence of absolute acoustic band gaps in two-dimensional solid phononic crystals. , 2001, Physical review letters.

[7]  P. Sheng,et al.  Locally resonant sonic materials , 2000, Science.

[8]  M Fink,et al.  Random multiple scattering of ultrasound. II. Is time reversal a self-averaging process? , 2001, Physical review. E, Statistical, nonlinear, and soft matter physics.

[9]  P. Sheng,et al.  Focusing of sound in a 3D phononic crystal. , 2004, Physical review letters.

[10]  Economou,et al.  Classical wave propagation in periodic structures: Cermet versus network topology. , 1993, Physical review. B, Condensed matter.

[11]  Jean-Jacques Greffet,et al.  Reciprocity of evanescent electromagnetic waves , 1998 .