Polariton Dispersion of Ferroelectric Super Lattices at Various Temperatures

Abstract

The variation of the optical parameters such as the static dielectric constant, high frequency dielectric constant, transverse optical phonon frequency and longitudinal optical phonon frequency are studied for the ferroelectric materials like LiNbO₃ and LiTaO₃ at various temperatures. Hence the behaviour of phonon polaritons at these temperatures is discussed. It is found that when the temperature increases the dispersion shifts to new values. The polaritonic gap, within which no electromagnetic radiation can pass through, is almost same at all the temperatures except at the transition region. It is extended to LiNbO₃/LiTaO₃ superlattices. The behaviour of various modes of the phonon polariton dispersion is investigated systematically.