Currently optical fibers are drawn from preforms that require complicated processing steps and repeated batch-type handling. This increases the cost of the ultimate fiber because preform cost often represents more than 50% of the fiber cost. Additionally, since the preform rod has a specific volume, the length of the fiber that can be drawn is limited. This increases the number of optical couplers and amplifiers needed to achieve a very long signal path from the relatively short segments drawn. This also adds potential variability in optical performance and an increased probability of mechanically weak points in the fiber system. Both these aspects further increase the system cost. These problems can be reduced by developing a novel process in which glass precursor coatings are formed on a continuously moving filamentary core of material which becomes a part of the ultimately formed optical fiber. Optimizing the process to yield strong, low loss optical fibers of ultra long length should significantly lower the cost of optical fiber systems for various military and commercial applications for communications. The sol-gel process also provides the opportunity to develop specialty fibers/sensors for environmental and other applications with improved reliability and reduced cost. The proposed Phase II study involves further refinement and development of a commercially viable process for applying sol-gel glass coatings to silica core filaments and vitrifying the coatings into high quality optical fibers, comparable in mechanical and optical properties with fibers obtained by the current preform method. A rad-hard all silica optical fiber is expected to be one product of Phase II studies. Optimization begun in Phase II should yield ultra long length optical fibers with uniform, high quality optical and mechanical properties.
Benefits: The development of ultra long, high quality fibers will greatly reduce the cost of optical fiber systems and improve system reliability by reducing the need for coupling shorterlengths. The sol-gel process also holds promise to produce fibers with specialty claddings useful as distributed sensors and as rad-hard fibers. The commercial potential of these latter products may b
