An acoustic power divider with uniform phase and compressibility-near-zero effective material properties

Abstract

Materials with properties which can be described by a near-zero index have received much attention in the fields of microwave electromagnetics, optics, and acoustics, due to their extraordinary capabilities in wave manipulation. It was recently demonstrated, theoretically and experimentally, that acoustic media can support near-zero-index propagation, in which the effective compressibility of a waveguide channel approaches zero. In principle, this allows the complete tunneling of acoustic waves with nearly infinite wavelength (or equivalently, uniform phase). In this work, we show that these concepts can be extended to realize a novel acoustic power divider, which permits the tunneling of acoustic power to an arbitrary number of output ports, where the phase shift with respect to the input signal can be selected to be either 0 or 180 degrees. Analytical and numerical models which describe the behavior of the power divider, are presented. We conclude with an analysis that describes the limitations and trade-offs that occur due to losses as the device size is scaled.