Photorefractive properties of tetragonal potassium tantalate-niobate crystals

Abstract

Diffraction efficiencies, decay time constants and gain coefficients of two nominally pure KTN crystals are investigated for different spatial frequencies and externally applied fields. The experimental results can be described by a model which assumes one kind of photorefractive centers and takes into account electron-hole competition and space charge field limitations due to the available trap density. Especially the last effect considerably decreases light-induced refractive index changes of the crystals, in spite of very large electrooptic coefficients. © 1993.