Dynamics of IR absorption caused by hydroxyl groups and its effect on refractive index evolution in UV-exposed, hydrogen-loaded GeO/sub 2/-doped fibers

Summary form only given. The use of room-temperature hydrogen loading as a means of sensitising GeO/sub 2/-doped silica glasses for UV exposure is an attractive technique for inducing large refractive index changes in optical fibers. We investigate the simultaneous photoinduced generation of Ge/Si-OH groups and refractive index changes during UV exposure of hydrogen-loaded, GeO/sub 2/-doped fibers. The UV-induced index change was measured directly using a technique that employs an unbalanced Mach-Zehnder interferometer and its growth dynamics was related with the increase in the Ge/Si-OH concentration. The measured increase in fiber core refractive index at 1525 nm is obtained as a function of the exposure time. Based on our experimental observations, we report a strong correlation between the evolution of the UV-induced index change and the growth dynamics of the total OH concentration.