INDEX PROFILE CONTROL USING LI+ FOR NA+ EXCHANGE IN ALUMINOSILICATE GLASSES

Two new techniques for altering the gradient-index profile shape are presented using ion exchange of Li+ for Na+ in an aluminosilicate glass. By varying the alkali concentration in the base glass and salt melt, the functional form of the index profile is modified to range in shape from convex to concave. The success of these techniques is attributed to the unusual characteristics of the initial system, which are shown to be caused by a nonlinear dependence of refractive index on dopant concentration. © 1990 Optical Society of America.