Stress-induced absorption of a birefringence-reduced polymer optical fiber with doped core

A poly[(methyl methacrylate/2,2,2-trifluoroethyl methacrylate/benzyl methacrylate) = 52/42/6 (w/w/w)] copolymer was used to form the core of a polymer optical fiber (POF) with the purpose of fabricating a birefringence-reduced core (BRC). The fabricated POF showed almost no phase shift, regardless of the stress that was applied to the fiber. Therefore, it is possible to maintain the polarization in the POF core, which is an important factor for detection of the direction in which stress is applied to the POF. To detect the stress direction, the core of a BRC-POF was doped with dichroic dye. A doped BRC-POF that was fabricated using magenta dye showed variations in its output under operating conditions where the stress vector and the incident polarization formed different angular relationships. The results presented here are considered to be applicable to detailed structural monitoring using POFs.