EXPLAINING THE OPTICAL FUSE

Experiments show that the characteristic periodic damage pattern that results from the optical fuse can be produced by purely thermal means by heating the fiber to temperatures in the 700-1000-degrees-C range in the absence of light. The nature of the damage region bubbles suggests local temperatures high enough to soften the fiber core. The additional energy required may be supplied by an exothermic mechanism. Consideration of activated interstitial diffusion of various potential oxidants in silica suggests that diffusion-limited reactions of unoxidized sites with O2 could be responsible.