Two-channel ultrasonic switch based on two-dimensional fluid/fluid phononic crystals with composite lattices

We report the design procedure for an ultrasonic two-channel thermo-switch composed of two line-defect waveguides coupled through four similar composite lattices all based on a two-dimensional fluid/fluid phononic crystal platform. The phononic crystal platform consists of a periodic array of infinitely long rods of ethyl nonafluorobutyl ether embedded in mercury background. The difference in the sound velocity and mass density provides a narrow-pass band in the resonant mode spectrum of composite lattice, required for the coupling functionality. Moreover, the temperature dependence of the elastic constants of utilized fluids have also enabled the switching of the presented structure. We show that the addition of an appropriate scatterer at the center of structure can reduce the scattering loss and enhance the confinement and wave propagation efficiency. To the best of our knowledge, this is for the first time that a 2 × 2 ultrasonic switch has been proposed in two-dimensional fluid/fluid phononic crystals with composite lattice. (paper)