Resumen:
A coupled resonant acoustic waveguide (CRAW)in a phononic crystal (PnC)was engineered to
manipulate the propagation of ultrasonic waves within a conventional phononic bandgap for
wavelength division multiplexing. The PnC device included two, forked, distinct CRAW waveguide
channels that exhibited strong frequency and mode selectivity. Each branch was composed of cavities
of differing volumes, with each giving rise to deep and shallow‘impurity’states. These states were
utilized to select frequency windows where transmission along the channels was suppressed distinctly
for each channel. Though completely a linear system, the mode sensitivity of each CRAW waveguide
channel produced apparent nonlinear power dependence along each branch. Nonlinearity in the
system arises from the combination of the mode sensitivity of each CRAW channel and small
variations in the shape of the incident wavefront as a function of input power. The all-acoustic effect
was then leveraged to realize an ultrasonic, spatial signal modulator, and logic element operating at
398 and 450 kHz using input power.