Polarization-maintaining mechanism of a birefringence-reduced plastic optical fiber fabricated using poly(methyl methacrylate/benzyl methacrylate) copolymer

In order to propose a multimode polarization-maintaining fiber in a large core diameter, polarization-maintaining graded-index plastic optical fiber (PMGIPOF) was fabricated using a birefringence-reduced copolymer of poly(methyl methacrylate/benzyl methacrylate). Successful reduction of orientational birefringence in the PMGIPOF was verified using polarized optical microscopy. The extinction ratio measured from the PMGIPOF was significantly higher than the value obtained for the step-index (SI) POF (14.3 and 0.5 dB for 1 m, respectively). Photoelastic birefringence in the PMGIPOF was studied using fiber macrobending. Retardation induced by the macrobending was observed in a manner of high regularity in the PMGIPOF, where as the other types of POFs did not show such regularity. Furthermore, the polarization-maintaining property of the PMGIPOF was effective at maximum 10 m propagation.