Complex Phonon-Polariton Dispersion of Congruent Lithium Niobate Studied by THz Time-Domain Spectroscopy.

Complex polariton dispersion relations were determined in the congruent lithium niobate crystal using the latest terahertz time domain spectroscopy. We measured the power and phase transmission spectra by the coherent THz radiation. The complex dispersion relations of phonon polariton frequency and damping have been investigated simply by rotating the polarization plane of an incident beam. These dispersive properties have been consistently reproduced by the damped harmonic oscillator model related to the lowest frequency infrared active modes. [ABSTRACT FROM AUTHOR]