Design and Fabrication of Polymer Cross Fiber for Large-Core Single-Mode Operation

In this paper, we report the fabrication of a polymer segmented cladding fiber (SCF) that contains four high-index cladding segments, which is coined the ldquocross fiber.rdquo In particular, we highlight the difficulties experienced in the fabrication process. We find that severe shear stresses at the interface between segments can be created and, as a result, the preform tends to shatter resulting in the formation of air bubbles during fiber drawing. The problem becomes more serious as the number of segments increases. Because the single-mode performance of a SCF depends only weakly on the number of the high-index cladding segments, to minimize the fabrication difficulty, it is sufficient to use a SCF with four segments, namely, a cross fiber, for the realization of large-core single-mode operation.