| Abstract: | The selection of the coatings/polymers used to fabricate optical fibers has been shown to be very important in determining their optical, mechanical, and connectorization performance. Material properties such as refractive index, optical transmission, and thermal coefficient of linear expansion are critical for coatings functioning as cladding materials. Coating adhesion to the glass surface, water absorption and water vapor permeation, as well as the ability to passivate the glass surface, have strong affects on the strength and fatigue behavior of fibers. Hard, thin, adhesive primary coatings are beneficial in making connectorization easier and more reliable. Many of the preferred properties for the fiber coating are different from those preferred for electrical wire, not only because light must be transmitted rather than electricity, but also because of the brittle nature of the silica substrate and the coupling between physical displacements and light transmission within the guiding material (microbend effects). The selection of cable materials is quite similar to that employed in the electrical wire and cable field. Much more attention must be given to cable design than for the latter. Designs/applications requiring tight jacketed or filled cables put special constraints on the selection of materials for the optical cables, which are more restrictive than for electrical cables. |
