Optical Properties Of Low Loss Fluoride Glass-Cladded Fibers

Recent improvements in preform processing and fiber drawing techniques have resulted in glass-cladded fluoride glass fibers having losses under 10 dB/km. Multicomponent zirconium fluoride glass was used, and care was taken to reduce impurities such as transition metals and water. The reduction of scattering centers was also a major concern. Preforms were made using the rotational casting approach, which resulted in glass-cladded preforms having no observable core-clad defects. The preforms were coated with teflon, and drawn into fibers using an r.f. induction furnace. The optical attenuation of the fibers was measured in the infrared region. The minimum loss occurred around 2.5 microns. The fiber scattering loss was also measured. A variety of lasers were used for this measurement, including an infrared color-center laser to obtain scattering data directly in the infrared region.