Design of the interfacial shear strength between the glass fiber and primary coating in double-coated optical fibers

The design of the interfacial shear strength between the glass fiber and primary coating in double-coated optical fibers is investigated. An optical fiber with higher interfacial shear strength possesses a better ability to prevent the delamination of polymeric coatings, but it makes the strip of coating materials more difficult. Based on the consideration of the stripping ability and delamination of polymeric coatings, the optimal value of the interfacial sheer strength is dependent on the tensile strength of the glass fiber, the damping condition of the tensile force applied on the optical fiber, the fiber's length, and material's properties of polymeric coatings. In the real applications of optical fibers, the tensile strength of the glass fiber can be regarded as the allowable external load induced axial stress in the glass fiber which usually is a fraction of the proof-test setting value. The clamping condition of the optical fiber can be regarded that the tensile force is only applied on the both ends of the secondary coating. The fiber's length can be regarded as the minimum operating length, for example, 10 mm. A higher value of the interfacial shear strength is required for optical fibers with higher Young's modulus of the primary coating, lower Poisson's ratio of the primary coating, and lower radius and Young's modulus of the secondary coating. Finally, the limitation of the lateral load on the optical fibers to prevent the delamination of polymeric coatings is also discussed.