Strengthening of Optical Fibers by Molecular Stuffing

Even though glass has high intrinsic strength, it is a brittle material which suffers strength degradation due to static fatigue. Stringent control of preform preparation, drawing conditions and immediate coating with protective materials may limit the initial flaw population in glass fibers, but no coating or pretreatment can completely prevent strength degradation under tensile loading conditions. If the fiber surface is under compression, however, one can guarantee the preservation of the initial tensile strength for static loads less than the compression and can greatly increase the time to failure for larger loads. This paper discusses one preform fabrication technique, “Molecular Stuffing” which is especially suited to producing optical fibers having high residual surface compression. The basic aspects of molecular stuffing are discussed with particular emphasis on its applicability to strengthening.