Transverse birefringence in polymer optical fibre introduced in drawing process

Abstract

In this work, we investigated the transverse birefringence in PMMA-based polymer optical fiber introduced in the drawing process. We proposed a sime theoretical model that attributes the induced transverse birefringence to three major factors: quenching effect, molecular alignment, and thermal expansion mismatch. Various experiments have been designed and performed to ascertain and identify the individual contribution of the three factors. In our experiments, polymer optical fibers are drawn under varying conditions and end their transverse birefringence is measured using the interferometric microscope method. These experiments have determined the respective contributions of the three factors and produced important findings agreeable to our theoretical model: the birefringence increases with the drawing speed ratio; the quenching-induced birefringence has profile of parabolic shape which can be removed by annealing; the profile of birefringence due to thermal expansion mismatch has an abrupt change at the core-cladding interface; and the birefringence induced by molecular alignment is constant across the fiber, and the magnitude is small.