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 scatte ring and infrared absorption. Furthermore, these glasses are drawn int o fibers to examine the stability against crystallization in the fiber drawing process. All glasses exhibit Light scattering intensity highe r than that of silica glass. Fluorophosphate glasses are crystallized during fiber drawing. The present evaluation reveals that silicate gla ss, C7, is suited for loci-loss fibers. The intrinsic minimum attenuat ion is predicted to be 0.8 dB/km at 1.2 mu m, which is somewhat larger than that of silica glass. In addition, the estimations for density a nd concentration fluctuations indicate that concentration fluctuation dominates the light scattering in multicomponent optical glass.