Optical Spectroscopy of Defects in Yttrium Orthovanadate (YVO4) Crystals

Yttrium orthovanadate (YVO4) is an insulating crystal used in several important and emerging optical technologies such as a solid-state laser host material and in fiber optic components for telecommunications. We are engaged in a study of the growth-related and radiation-related point defects that result in discoloration of commercial quality YVO4. These defects can reduce the usefulness of the material. Alternatively, these same defects may actually play a beneficial role in the use of YVO4 for other applications, such as the observed Anti-Stokes Luminescence (light which is converted to a higher energy due to a two-photon process in the crystal) which could make the YVO4 a candidate for blue lasers. It has been surmised [1] that some of these ``useful'' defects are related to oxygen vacancies in the crystal, so we are exploring the effects on defects after annealing the YVO4 in Oxygen and other gas atmospheres. [1] Anti-Stokes emission in undoped YVO4, W. Ryba-Romanowksi, S. Golab, P. Solarz, and G. Dominiak-Dzik, Applied Physics Letters, 80, 1183 (2002).