Application of simultaneous strain and temperature measurement technique using polarization maintaining fiber Bragg grating for distributed sensing based on OFDR

Abstract

We have developed fiber-optic distributed sensors based on optical frequency domain reflectometry (OFDR). This sensing system utilizes long-length fiber Bragg gratings (FBGs) and is able to measure strain or temperature distributions with the high spatial resolution along FBGs. In this paper we inscribe a long-length FBG into Polarization-maintaining AND Absorption-reducing fiber (PANDA-FBG) for simultaneous strain and temperature measurements. Applying PANDA-FBG to OFDR system, we perform both simultaneous measurements and distributed sensing with a single PANDA-FBG. In experiments we bonded the PANDA-FBG on a stainless beam and applied several steps of temperature changes and four-point bending loads. We performed simultaneous measurements over the local area of the beam. Based on the results, we compensated the temperature changes and calculated the strain distribution along the whole part of the beam. The experimental results showed the applicability of this method.