An analytical model is developed to predict the temporal evolution of the lattice polarization in ferroelectric nanomembranes upon the excitation by a terahertz (THz) electromagnetic pulse of an arbitrary waveform and the concurrent transmission of the THz pulse in both linear and nonlinear regimes. It involves the use of the perturbation method to solve the equation of motion for the lattice polarization in both unclamped and strained ferroelectric nanomembranes within the framework of Landau-Ginzburg-Devonshire theory. The model is applicable to perovskite oxides such as ${\mathrm{BaTiO}}_3$ and ${\mathrm{SrTiO}}_3$, wurtzite ${\mathrm{Al}}_{1-x}{\mathrm{Sc}}_x\mathrm{N}$, and trigonal ${\mathrm{LiNbO}}_3$. Our analytical model provides a theoretical basis for determining the thermodynamic and kinetic parameters of ferroelectric materials through a THz transmission experiment. The calculation results also suggest an approach to reversing the chirality of a circularly polarized THz pulse by harnessing the resonant polarization-photon coupling in ferroelectrics. This capability of chirality reversal, along with the high tunability from a strain applied along any arbitrarily oriented in-plane axis, provides new opportunities for THz wave modulation without relying on complex metasurface designs.

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• Ferroelectricity
• Ferroelectrics
• Classical electromagnetism
• Electromagnetic wave theory
• Finite-difference time-domain method
• Landau-Ginzburg-Devonshire theory
• Phase-field modeling