Plastic Optical Fiber Sensor for Humidity Measurement Based on Losses Induced in the Transition Region of a Bended Fiber

摘要

This document presents a humidity sensor using hydrogels deposited on the surface of the side-polished core of an U-shape curved plastic optical fiber (POF). With the aim to increase the sensitivity of the sensor, the polished side has been performed in the transition region of the bended fiber. The angle of the side-polishing, in relation to the plane of the section of the fiber, corresponds to the critical angle of a straight fiber. The comparison between a polishing with lateral symmetry, i.e. at the center of the curvature, and a polished side in the transition region shows a decrease in the losses of up to 2 dB using a POF cable.