  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.
