OTDR-BASED TECHNIQUE FOR DETECTING SIGNALS OF FBG SENSORS IN THE WIDE SPECTRAL RANGE FOR MEASURING STRAIN AND TEMPERATURE

摘要

The paper presents a reflectometric technique for interrogation of multiple fiber Bragg grating (FBG) sensors based on conventional optical time domain reflectometery (OTDR). The method proposed rests on the differential measurement of FBGs' response to a short probing laser pulse. Implementation of differential measurement principle using several reference FBGs allowed us to eliminate the susceptibility of the system to intensity fluctuations as well as to increase the measurement range as compared to the previous developments. The experimental threshold sensitivity amounted to ~50 ustrain with the measurement range being defined by the number of reference FBGs and limited only by optical fiber tensile strength. Due to its simplicity, efficiency and usage of conventional OTDR equipment the proposed FBG interrogation technique can find a wide range of applications dealing with strain and temperature measurements.