RAMAN-STUDY OF CSKTIOPO4 WAVE-GUIDES

Planar waveguides were produced by K+-Cs+ exchange of Z-cut KTiOPO4 si ngle domain crystals. The analysis of the refractive index profile has shown an exponential Cs+ distribution in the exchanged layers. By exc iting different waveguide modes, Raman spectra were obtained from guid e depths with varying Cs doping. Significant changes have been observe d between Raman spectra of Cs:KTiOPO4 and those of pure KTiOPO4 only i n the region of external vibrations while the internal modes, due to v ibrations of the TiO6 and PO4 groups, are practically the same. The ba nds corresponding to the external vibrations were found to be strongly influenced by the substitution indicating strong disorder in the latt ice, and possibly a structural phase transition. Furthermore, Raman sp ectroscopy proves to be an alternative technique for determining varia tion in Cs composition.