The effect of fabrication parameters on the cleaving of microstructured polymer optical fibers

A key step towards the commercialization of microstructured polymer optical fibers is the ability to cleave and splice them. The cleaving of polymer optical fiber (whether by cutting or fracture) depends upon the mechanical properties of the material. These in turn depend on the conditions under which the fiber is drawn from the preform. The relationship between fiber draw conditions, mechanical properties of the drawn fiber and the ability to cut the heated fiber with a hot razor blade has been investigated for PMMA fibers of varying hole structure. Differential scanning calorimetry measurements indicate that the type of PMMA used exhibits two 'relaxations' with inflexion points at 115±3oC and 80±2oC respectively, independent of draw conditions. The first of these is in the range expected for the α-relaxation. The origin of the second is unknown. Dynamic mechanical analysis of fiber samples indicates that the temperature dependence of the elastic and loss moduli of the fiber vary significantly with draw conditions. The end-face produced by cutting with a razor blade also varies with draw conditions. Fiber drawn under high tension splinters during cutting and fiber drawn under low tension undergoes ductile deformation and fracture. However for intermediate draw conditions the fiber can be cleanly cut with a razor blade at a temperature of 80±10oC.

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