Drastic sensitivity enhancement of temperature sensing based on multimodal interference in polymer optical fibers

It has been reported that temperature sensors based on modal interference in perfluorinated graded-index polymer optical fibers show extremely high temperature sensitivity at room temperature. In this work, we confirm that the temperature sensitivity (absolute value) is significantly enhanced when the temperature increases toward similar to 70 degrees C, which is close to the glass-transition temperature of the core polymer. When the core diameter is 62.5 mu m, the sensitivity at 72 degrees C at 1300 nm is 202 nm/degrees C/m, which is approximately 26 times the value obtained at room temperature and >7000 times the highest value previously reported using a silica multimode fiber. (C) 2015 The Japan Society of Applied Physics