Designing phononic crystal based tunable four-channel acoustic demultiplexer

Abstract

We propose a tunable four-channel acoustic demultiplexer, based on a fork-shaped phononic crystal (PnC) structure, having four output ports. A square lattice of cylindrical water inclusions in a mercury matrix, separate by ultra-thin elastically solid shells, characterizes the PnC platform. We used a plane wave expansion (PWE) method to calculate the PnC band diagram. There are four cylindrical resonant cavities of different inner radii, filled with the methyl nonafluorobutyl ether (MNE), placed in correspondence of the throat of each output port. Using the finite difference time domain (FDTD) numerical approach, we show that the proposed device can demultiplex a given broadband acoustic signal to four narrowband channels of ultra-high quality factors and interchannel cross talks less than −32 dB. Moreover, simulations show that the proposed device besides its demultiplexing functionality has the potential of sensing pressure and temperature and also the capability of determining the properties of the cavity fluid.