INFLUENCE OF IMPURITY IRON IONS ON NONLIN EAR COLORATION OF ALKALI-SILICATE GLASSES

A study was made of the role of iron impurity ions in the formation an d dissociation of colour centres in alkali-silicate glasses in the cou rse of multiphoton absorption of laser radiation. An increase in the c oncentration of Fe2O3 enhanced the residual absorption by stable hole colour centres and reduced considerably the lifetime of unstable elect ron colour centres. Repeated irradiation of glasses containing a small amount of the impurity increased the residual absorption, whereas the induced absorption (measured immediately after the action of a radiat ion pulse) did not change from one pulse to the next and was governed solely by the radiation power density. An increase in the Fe2O3 concen tration destroyed this effect.