Viscosity of GeO/sub 2/-doped silica glasses

The viscosity of GeO/sub 2/-doped silica glasses is experimentally evaluated and found to be expressed as a function of the monoexponential form /spl eta//sub 0/ exp(/spl minus/A/spl Delta/e), where /spl eta//sub 0/ is the viscosity of pure silica glass, A is a positive constant, and /spl Delta/e is an equivalent relative-index difference that is introduced for a silica glass with nonuniform dopant distribution in its cross section. The constant A for GeO/sub 2/-doped silica glasses is found to be about 0.5, which is much smaller than that for fluorine-doped silica glasses and has almost no temperature dependence between 1400/spl deg/C and 2200/spl deg/C.<
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