Raman scattering from phonon-polaritons in GaN

Bulk phonon-polaritons in wurtzite GaN have been studied. Polarized Raman spectra have been measured using forward Raman-scattering geometry with annular apertures. Theoretical calculations have been carried out on the dispersion relation and Raman-scattering efficiency of the bulk phonon-polaritons. These were used to assign the observed signals to those from the bulk phonon-polaritons, which are a mixture of the quasi-transverse-optical phonon and an electromagnetic wave. A brief discussion of the components of the Raman tensor is also given.