| 摘要 |
PURPOSE:To prevent deteriorations in the transmission characteristics even when external force is applied, by disposing optical fiber in the longutidinal direction of the tube wall part of plastic pipes. CONSTITUTION:An optical fiber cord 11 is composed of a plastic pipe 14 and four optical fibers 12. The outer circumferences of the optical fibers 12 are coated with a primary coat 13 and disposed in an axial direction of a tube wall part 15 of the plastic pipe 14. Therefore, the tube wall part 15 of the plastic pipe 14 acts as the secondary cover of the optical fiber 12, and a clearance 16 is formed at the center of the cord 11. When lateral pressure P is applied to the optical fiver cord 11 composed in such way, the plastic pipe 14 itself makes an elastic deformation. Since, at this time, the lateral pressure P is absorbed by the deformation of the whole pipe 14, the ratio sigma/P of stress sigma produced in the optical fiber 12 to the lateral pressure P becomes almost 0. Therefore, deteriorations in the transmission characteristics can be prevented. |
