Analytical Model and Dynamical Phase-Field Simulation of Terahertz Transmission Across Ferroelectrics

We theoretically investigate the steady-state transmission of continuousterahertz (THz) wave across a freestanding ferroelectric slab. Based on theLandau-Ginzburg-Devonshire theory of ferroelectrics and the coupled equationsof motion for polarization and electromagnetic (EM) waves, we derive theanalytical expressions of the frequency- and thickness-dependent dielectricsusceptibility and transmission coefficient at the thin slab limit in theharmonic excitation regime. When the slab thickness is much smaller than theTHz wavelength in the ferroelectric, the analytical predictions agree well withthe numerical simulations from a dynamical phase-field model that incorporatesthe coupled dynamics of strain, polarization, and EM wave in multiphasesystems. At larger thicknesses, the transmission is mainly determined by thefrequency-dependent attenuation of THz waves in the ferroelectric and theformation of a standing polarization/THz wave. Our results advance theunderstanding of the interaction between THz wave and ferroelectrics andsuggest the potential of exploiting ferroelectrics to achievelow-heat-dissipation, nonvolatile voltage modulation of THz transmission forhigh-data-rate wireless communication.