High-modulus low-linear-expansion-coefficient loose-jacket optical fibers

Optical fibers loosely jacketed with high-modulus low-linear-expansion-coefficient polymers have been proposed, and the mechanical, thermal, and optical properties have been investigated. The loose-jacket tube is made of highly oriented polyoxymethylene (POM), which is produced by tensile-drawing the isotropic POM tube with dielectric heating. The oriented POM exhibits Young\´s moduli 20-40 GPa and linear expansion coefficients of the order of C^-1. Owing to the low linear expansion coefficients of the material, the oriented POM loose-jacket optical fiber has no low-temperature excess losses, which is due to fiber bends caused by thermal contraction of the loose tube, in the C temperature range.