Design of tightly jacketed double-coated optical fibers to minimize thermally induced delamination of polymeric coatings

To maintain its mechanical strength, the glass fiber of optical fibers is c oated by polymeric materials during the fabrication process. However, when the thermally induced sheer stress at the interface of the glass fiber and primary coating is larger than its adhesive stress, the polymeric coatings will be delaminated from the glass fiber, and the optical fiber will lose i ts mechanical strength. The design of tightly jacketed double-coated optica l fibers to minimize the thermally induced delamination of polymeric coatin gs is investigated. To minimize the coating's delamination, the thermally i nduced shear stress at the interface of the glass fiber and primary coating should be reduced. The method to minimize such a shear stress is to select suitable polymeric coatings as follows. The thickness and Poisson's ratio of the primary coating should be increased. On the other hand, Young's modu lus of the primary coating, the thickness, Young's modulus and thermal expa nsion coefficient of the secondary coating, and Young's modulus and thermal expansion coefficient of the jacket should be decreased. Finally, the opti mal design of commercialized tightly jacketed double-coated optical fibers to minimize the thermally induced coating's delamination is also discussed. (C) 1999 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(9 9)01909-1].