ULTRAVIOLET PHOTOLYTIC-INDUCED CHANGES IN OPTICAL FIBERS - THE THERMAL-EXPANSION COEFFICIENT

We show that recent experimental results of Wong et al. [Opt. Lett. 17 , 1773 (1992)] on the effect of UV photolytic processing on the birefr ingence of elliptical-core fibers arise from a 15-30% reduction of the coefficient of thermal expansion of the germanosilicate core. An expl anation based on reconfiguration of the glass network to minimize the stress energy during UV processing is proposed.