Recent Advances in Furnace CVD Preform Fabrication Process

摘要

Modified chemical vapor deposition process is versatile and convenient for fabrication of optical fiber core preforms. For telecom fiber fabrication, which is characterized by large preform size and low production cost, traditional MCVD process, using oxyhydrogen torch as a heat source shows several disadvantages. Core preform size is limited by the heat transfer process through the deposition tube wall, homogeneity of deposited layers both in longitudinal and axial direction influences the overall yield and fabrication of low water peak fiber is demanding. We have looked for an alternative heat source both for deposition and collapse processes in MCVD preform fabrication, adopting the use of inductive graphite furnace, of the type similar to fiber drawing furnace. We present the results of our preliminary testing and comparison between MCVD process using traditional oxyhydrogen torches and furnace. It has been shown that use of a furnace in MCVD process can offer several advantages, permitting fabrication of large and homogenous preforms with increased productivity, thus making it more competitive and economically feasible.