Liang-Hsun Lai

Microbending losses in double-coated optical fibers caused by axial strain-induced creep deformation of polymeric coatings

The viscoelastic behavior of commercial UV-cured polymeric coatings of optical fibers is evaluated using dynamic mechanic analysis. The results indicate that relaxation of stresses and/or strains in these coatings occurs by creep deformation. The axial strain-induced viscoelastic stresses in optical fibers are derived from the exact viscoelastic behavior of the polymeric coatings. Compressive radial stress on the glass fiber produces microbending losses, and therefore, microbending losses in double-coated optical fibers that are caused by axial strain-induced creep deformation of polymeric coatings are investigated. These microbending losses can be minimized by suitably selecting the thickness and physical properties of the polymeric coatings, as follows. The radius, Poisson’s ratio, and strain ratio of the primary coating should be increased, but the Young’s modulus and relaxation time of the primary coating should be decreased. The radius, Young’s modulus, Poisson’s ratio, and strain ratio of the second...