Optical fiber and optical fiber cable having a first jacket layer and a second jacket layer and a coefficient of thermal expansion selecting method

摘要

An improved optical fiber is described. The optical fiber comprises: a fiber glass structure; a first jacket layer made of a soft curable resin and directly covering the external surface of said fiber glass structure; and a second jacket layer made of a rigid curable resin and covering the external surface of said fiber glass structure through said first jacket layer. The mechanical factors of said fiber glass structure, the mechanical factors of said first jacket layer and the mechanical factors of said second jacket layer are selected in order that the Young's modulus of said first jacket layer is larger than the average tensile stress (&sgr;_r+&sgr;_&thgr;+&sgr;_z)/3 as applied to said first jacket layer 5 while the resin temperature of UV curable resins largely falls from the temperature when the rigid UV curable resin starts hardening to the temperature when the hardening is finished.