Evaluation of Optical Glasses for Low-Loss Fibers: Optical Attenuation and Fiber Drawing Ability

Optical attenuation of commercial optical glasses with low refractive indices is evaluated on the basis of the measurements for light scattering and infrared absorption. Furthermore, these glasses are drawn into fibers to examine the stability against crystallization in the fiber drawing process. All glasses exhibit light scattering intensity higher than that of silica glass. Fluorophosphate glasses are crystallized during fiber drawing. The present evaluation reveals that silicate glass, C7, is suited for low-loss fibers. The intrinsic minimum attenuation is predicted to be 0.8 dB/km at 1.2 µm, which is somewhat larger than that of silica glass. In addition, the estimations for density and concentration fluctuations indicate that concentration fluctuation dominates the light scattering in multicomponent optical glass.