High-index optical wave-guides were prepared by using a simple proton-exchange process. The wave-guides were characterized optically, and the refractive index was found to vary with the depth of the wave-guide. The variation in refractive index exhibited a graded index profile, with the maximum surface index change being found at a wavelength of 0.633. From these proton-exchange data, it was deduced that the H diffusivity (figure 6) could be described by:

D (2/h) = 2.35 x 108exp[-75.63(kJ/mol)/RT]

C.Y.Shen, S.T.Wang: Japanese Journal of Applied Physics, 1996, 35[2-10B], L1333-5