Extremal transmission and beating effect of acoustic waves in two-dimensional sonic crystals.

The extremal transmission of the acoustic wave near the Dirac point in two-dimensional (2D) sonic crystals, being inversely proportional to the thickness of sample, has been demonstrated experimentally for the first time. Some unusual beating effects have been observed experimentally, when the acoustic pulse transports through the 2D sonic crystal slabs. Such phenomena are completely different from the oscillations of the wave in a slab or cavity originating from the interface reflection or the Fabry-Perot effect. They can be regarded as an acoustic analogue effect to Zitterbewegung of the relativistic electron. The physical origination for the phenomenon has been analyzed.