Processing 100% Silica Optical Fiber Waveguides Using Sol-Gel Technology

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 is removed or 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 should provide the opportunity to develop specialty fibers/sensors for environmental and other applications with improved reliability and reduced cost. The proposed Phase I study involves a thorough investigation of state-of-the-art processing for applying sol-gel glass coatings to host 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. These results will be used as the starting point for the further development and optimization studies in Phase II to arrive at a reliable process to yield ultra long length optical fibers with uniform, high quality optical and mechanical properties.