Characteristics of carbon coatings on optical fibers prepared by plasma enhanced chemical vapor deposition using different argon/methane ratios Original Research Article

The effect of argon/methane ratios on the characteristics of carbon coatings on optical fibers prepared by plasma enhanced chemical vapor deposition is investigated. The argon/methane ratios are selected at 0, 1, 2, 4, 6, and 8. Results show that if the argon/methane ratio increases from 0 to 4, the deposition process is mainly sustained by the Penning effect. The Penning effect enhances the dissociation of the hydrocarbon gas molecules. The carbon coating shifts to the graphite-like carbon and the surface of the carbon coating becomes smoother. As the argon/methane ratio increases from 4 to 8, etching becomes more important. The sp2 Cdouble bond; length as m-dashC bonding in the carbon coating transforms from order into disorder. Because the disordered sp2 Cdouble bond; length as m-dashC bonding increases, the surface of the carbon coating becomes rougher. When the argon/methane ratio is 4, the surface roughness of the carbon coating is a minimum, while the water contact angle of carbon coating is a maximum. At this argon/methane ratio, the carbon coating has the best ability to minimize low temperature induced delamination or microcracks, so is the best for the production of a hermetically sealed optical fiber coating.