OPTICAL-DAMAGE OF W-DOPED KTIOPO4 NON-LINEAR SINGLE-CRYSTALS

A photochromic damage has been observed in W-doped KTP single crystals . The damage consists in the growth of a broad optical absorption in t he visible and near infrared. It has been determined that the excitati on spectrum of this damage is mainly confined in the ultraviolet regio n. A complete annealing of the damage may be obtained by heating at 25 0 degrees C or above. The origin of the damage has been mostly related with the presence of W4+ ions behaving as electron donors. Ti4+ ions trap electrons and the Ti3+ ions formed are responsible of the optical absorption observed.