Abstract

Continuum models are developed which describe the optical as well as the acoustic displacements in polar media, including corrections to the harmonic approximation. These lead to simple phonon modes in locally isotropic media, and confirm a previously conjectured dispersion relation. They are used to study phonon lifetimes and the effects of heterostructure confinement. It is found that the lifetime of confined LO phonons decaying into delocalized acoustic phonons is substantially independent of size of the confining region.

© 1989 Optical Society of America