OPTICAL FIBER WITH PRIMARY COATING LAYER AND SECONDARY COATING LAYER, OPTICAL FIBER CABLE AND THEIR MANUFACTURING METHODS

摘要

PROBLEM TO BE SOLVED: To reduce a transmission loss of an optical fiber 1 caused by minute curving of fiberglass 3 by stabilizing the supporting condition of the fiberglass 3 with a primary coating layer 5.

SOLUTION: The optical fiber is comprised of the fiberglass, the primary coating layer composed of a soft curing resin directly covering the periphery of the fiberglass, and a secondary coating layer composed of a hard curing resin indirectly covering the periphery of the fiberglass through the primary coating layer. The Young's modulus of the soft curing resin is very lower than that of the hard curing resin; and the relational expression between the linear expansion coefficientα1of the soft curing resin and the linear expansion coefficientα2of the hard curing resin is denoted by the formula (wherein the fiberglass radius is R0; the outside radius of the primary coating layer is R1; the Poisson's ratio of the soft curing resin isν1; the Poisson's ratio of the hard curing resin isν2; and the temperature variation of the curing resins between during hardening and at the end of hardening isΔT).

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