Simulation of Phonon-Polariton Generation and Propagation in Ferroelectric LiNbO3 Crystals

TL;DR

This paper models and simulates the generation and propagation of phonon-polaritons in ferroelectric LiNbO3 crystals using FDTD methods, revealing their dispersion relations and nonlinear generation mechanisms.

Contribution

It introduces a novel simulation approach combining FDTD with a harmonic oscillator model to study phonon-polaritons in LiNbO3, including nonlinear generation via ISRS.

Findings

Simulated phonon-polariton dispersion relation in LiNbO3.

Demonstrated phonon-polariton generation through impulsive stimulated Raman scattering.

Validated the model's ability to illustrate key features of phonon-polaritons.

Abstract

We simulate propagation of phonon-polaritons (admixtures of polar lattice vibrations and electromagnetic waves) in ferroelectric LiNbO3 with a model that consists of a spatially periodic array of harmonic oscillators coupled to THz electromagnetic waves through an electric dipole moment. We show that when this model is combined with the auxiliary differential equation method of finite difference time domain (FDTD) simulations, the salient features of phonon-polaritons may be illustrated. Further, we introduce second order nonlinear coupling to an optical field to demonstrate phonon-polariton generation by impulsive stimulated Raman scattering (ISRS). The phonon-polariton dispersion relation in bulk ferroelectric LiNbO3 is determined from simulation.