Terahertz Time Domain Spectroscopy of Phonon-Polariton in Ferroelectric Bismuth Titanate.

This paper reports the first application of the terahertz time domain spectroscopy to phonon polariton dispersion. In order to determine polariton-dispersion of a high-quality ferroelectric bismuth titanate crystal plate, the phase delay was determined minutely as a function of THz radiation frequency in the region between 3 cm -1 and 100 cm -1 . The polarization dependence of polariton dispersion was clearly observed on the c-plate only by switching the polarization of an incident beam from E//a to E//b. The observed polariton dispersion relations are consistently explained by the calculation using Kurosawa's formula. [ABSTRACT FROM AUTHOR]