Roughening of Pristine Silica Glass Surface

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9616313 Tomozawa The most popular explanation of mechanical fatigue in glasses is the slow growth of a surface crack promoted by the stress corrosion reaction of glass with water or water vapor. It has been reported, however, that silica glass optical fibers can be made flaw-free and that these pristine glasses can also exhibit mechanical fatigue. Recent observations by atomic force microscopy (AFM) of glass fiber surfaces showed that the initial strength degradation of optical fibers is due to surface roughening rather than crack propagation. Thus it is necessary to understand the mechanism and kinetics of surface roughening of pristine glass surface in order to predict the fatigue life time of optical fiber correctly. The initial stage of the surface roughening kinetics of silica glass with or without stress will be investigated using an atomic force microscope and will be compared with the theory for the surface roughness development such as the noise-induced roughening theory and the stress-induced roughening theory. %%% The long term mechanical stability of silica glass optical fiber is an important concern in optical communications. Life time prediction of optical fibers requires the understanding of the mechanism of mechanical fatigue. In spite of extensive investigations, the mechanism remains unclear. Recent observations by atomic force microscopy (AFM) of glass fiber surfaces showed that the initial strength degradation of optical fibers is due to surface roughening rather than crack propagation. Thus it is necessary to understand the mechanism and kinetics of surface roughening of pristine glass surface in order to predict the fatigue life time of optical fiber correctly. The initial stage of the surface roughening kinetics of silica glass will be investigated and will be compared with the theory for the surface roughness development. ***