Reconfigurable locally resonant surface acoustic demultiplexing behavior in ZnO-based phononic crystal

We present the design and numerical investigation of a reconfigurable and miniature locally resonant surface acoustic wave demultiplexer based on a ZnO pillar phononic crystal, for the first time. Hollow cylinder line defects are used as waveguides, due to their good structural controllability over the local resonant waveguiding frequency and bandwidth. Two local resonant surface acoustic waveguides are designed and simulated as the output channels of the demultiplexer, and the shear-horizontal wave transmission spectra are calculated for each channel individually. The designed radio frequency demultiplexing output channels support frequencies of 4.14GHz and 4.28GHz, with respective bandwidths of 40MHz and 60MHz, while their spatial separation is just about 800nm. In order to achieve a reconfigurable output characteristic, the effect of acoustoelectric interaction in piezoelectric semiconductors is numerically simulated in this study. The acoustoelectric interaction causes an additional stiffness in ZnO that can be released by adding extra charge carriers, i.e., increasing conductivity, thus changing the effective elasticity of the ZnO structures and the guiding frequencies of the output channels. Two output frequencies show red shifts of about 100MHz and 150MHz by extremely increasing the conductivity of ZnO structures from 0.01S/m to 100S/m.