Yasuo Nakajima , Hiroki Tanaka , Kouji Mochizuki , Kazuyuki Fuse , Yoshihiro Arashitani , Takuya Nishimoto , Atsuyoshi Seno and Mitsunori Okada
Abstract
In general, optical fibers are coated with UV-curable resins--a soft primary coating and a hard secondary coating--to protect the glass. Under UV radiation curing heat is produced and it is known that, since the coefficient of thermal expansion (CTE) of the primary coating is greater than that of the secondary coating, a negative hydrostatic pressure is produced in the primary coating during the cooling process, resulting in a force acting to delaminate the primary coating from the glass. To achieve long-term reliability of optical fibers it is necessary to analyze the thermal strain and thermal stress that arise in the coatings of the fiber, and accordingly, in this work, we discuss methods for measuring the CTEs of the coatings and the modulus of elasticity of the secondary coating during the drawing process.
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