Multiplexing technique using photodetector arrays for quasi-distributed intensity variation optical fiber sensors system

Abstract

This paper presents the development and characterization of a multiplexing technique for quasi-distributed optical fiber sensors based on the intensity variation detection. The technique is based on an array of photodetectors coupled to the optical fiber, where each lateral section of the optical fiber is analyzed as a sensor along the optical fiber cable. In this case, the polymer optical fiber (POF) is used due to its higher diameter and higher flexibility, which leads not only to easier coupling between the photodetector and the fiber, but also higher sensitivity for mechanical parameters detection. The proposed technique is tested under two configurations. In the first one, two sensors are developed in a single POF cable for curvature detection along the optical fiber, where the results indicated the feasibility of using such sensors to detect the curvature position at 4 different regions along the POF with a root mean squared error (RMSE) as small as 0.49 cm. Then, a 4 sensor array is developed for simultaneous force and position detection along the optical fiber, where the results indicated relative errors below 5 % on the force amplitude and position detection. Therefore, the quasi-distributed intensity variation sensors can be readily used in shape reconstruction applications, which can be integrated not only in different flexible structure, but also in textiles for wearable sensors for health monitoring and biomechanics assessment.