A seri es of GR IN glass rods have been developed in Li2O-Na2O-Al2O3-TiO2-S
iO2 systems. Negative radial refractive index profiles were generated by ex
changing Na+ for Li+ ions in these glass rods. It has been observed that Ti
O2 plays a vital role in increase in the profile depth and maximum change i
n the refractive index because of its ambivalent nature. Change in the refr
active index can be further increased by increasing the concentration of ex
changing cation in the base glass. (C) 1998 Kluwer Academic Publishers.