Theory of terahertz pulse transmission through ferroelectric nanomembranes

TL;DR

This paper presents an analytical model for predicting how ferroelectric nanomembranes respond to terahertz pulses, enabling insights into their polarization dynamics and potential for THz wave modulation.

Contribution

It introduces a novel analytical framework based on Landau-Ginzburg-Devonshire theory for modeling THz pulse transmission in ferroelectric nanomembranes, including nonlinear effects.

Findings

Model predicts polarization evolution under THz excitation.

Reveals potential for chirality reversal of circularly polarized THz pulses.

Suggests strain-tunable THz wave modulation capabilities.

Abstract

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 the linear and the 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 BaTiO3 and SrTiO3, wurtzite Al1-xScxN, and trigonal LiNbO3. Our analytical model provides a theoretical basis for determining the thermodynamic and kinetic parameters of ferroelectric materials through 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.