OPTICAL FIBER CORE

摘要

Provided is an optical fiber core which is resistant to increase in transmission loss even when in high humidity or when submerged in water. A colored optical fiber core (22) is formed by applying a colored layer to an optical fiber wire (14) made from glass optical fiber coated with at least two coating layers which are a flexible layer and a rigid layer. The thermal expansion coefficient ratio between the coating layer of the optical fiber wire (14) before the colored layer is applied and the coating layer of the colored optical fiber core (22) after the colored layer is applied is at least 0.87. In addition, an optical fiber tape core (32) is formed by planarly arranging a plurality of colored optical fiber cores (22) and collectively covering the colored optical fiber cores (22) with tape resin. The thermal expansion coefficient ratio between the coating layer of the optical fiber wire before the colored layer is applied and the coating layer of the colored optical fiber core (22) after the colored layer is applied is at least 0.90.