Thermal stresses in metal-coated optical fibers

Abstract

The thermal stresses in metal-coated optical fibers are analyzed. Several thermal stresses are important in a metal-coated optical fiber. First, the interfacial radial stress would produce microbending loss. Secondly, the thermally induced axial force in the glass fiber would induce buckling of the fiber and also results in an increase of bending loss. Thirdly, when the interfacial shear stress is larger than its shear strength, the metal coating would be delaminated from the glass fiber. Finally, when the normal stress in the metal coating is larger than its tensile strength, the metal coating would be broken. These thermal stresses could be minimized by appropriately selecting physical properties of the metal coating and its thickness. To minimize these thermal stresses, the Young’s modulus, thermal expansion coefficient, and Poisson’s ratio of the metal coating should be decreased. On the other hand, the thickness of the metal coating has an optimal value. Based on the strength consideration, an optimal design of the metal-coated optical fiber also is considered.