Imaging of Energy Transduction in Ferroelectric-based Phononic Systems

The energy transduction between electromagnetic waves and elastic waves plays a key role in modern information technology. Due to the much smaller speed of sound than speed of light in solids, the scattering, diffraction, and localization of GHz acoustic phonons all take place in the mesoscopic length scale, which is challenging for spatially resolved studies. In this work, we demonstrate the imaging of electroacoustic energy transduction in ferroelectric domains by microwave impedance microscopy. Finite-element modeling is used to simulate the excitation of elastic waves and the dissipation of electrical power. In sharp contrast to the standing-wave patterns due to wave reflection from hard boundaries, the interference-like fringes with one-wavelength periodicity are the consequence of sign reversal of the piezoelectric coefficients in opposite domains. Combining the local imaging of energy transduction and numerical simulation, our approach may open up a new area to spatially resolve the field distribution in phonon-polariton systems.