STUDY OF CRYSTALS IN MEDIUM-WAVELENGTH AND LONG-WAVELENGTH IR RANGES BY SURFACE-ELECTROMAGNETIC-WAVE SPECTROSCOPY

First observation of excitation of surface electromagnetic waves (SEW) is reported in the reststrahlen region in for biaxial crystal KTiOPO4 (KTP) using a tunable CO2 laser around 10 mu m, and for CaF2, BaF2, M gO (cubic crystals), and LiNbO3 (uniaxial crystal) in the far IR using with a free-electron laser. The parameters of SEW propagation in thes e crystals have been obtained by the interference method of SEW phase spectroscopy, and the possibility of determining the complex dielectri c permittivity of crystals from the SEW propagation parameters demonst rated in the range of SEW existence. (C) 1998 American Institute of Ph ysics.