Low attenuation waveguide for leaky surface waves

A surface wave on a liquid/solid interface is well-known to radiate acoustic energy into the liquid and is therefore rapidly attenuated. In this work, we have been able to show by experiments and calculations that the proximity of another surface (layer 1 to layer 3 and layer 3 to layer 1) sustains the surface wave through long distances for layers of both plates and concentric tubes. In addition, even when the surface wave is reflected from a distant edge, the returning wave is sustained in the multi-layer system and can be easily detected. This is apparently one of the first observations of leaky surface waves traveling over large distances, in this case over a thousand wavelengths. The effect is modeled on the basis of a cooperative phenomenon between two interfaces separated by a water layer. The effect represents a valuable result in the wave propagation of acoustic surface waves and opens the door to many applications.