An intensity modulation based fiber-optic loop sensor for high sensitivity temperature measurement

The possibility of conducting high resolution temperature measurements using a power modulation based fiber-optic loop sensor (FOLS) is studied in this work. FOLS is an intensity modulation based sensor that is relatively inexpensive and easier to operate than frequency modulation based sensors. A sensing element is designed for temperature sensing while protecting FOLS from direct heat and possible thermal degradation over time. The resonance peaks present in the transmitted intensity signal are used to conduct high resolution temperature measurements. The measured temperature is found to closely match with the thermocouple measurements with an average difference of 2.53%. Also, the measurements are found to be repeatable. Theoretical and finite element results closely match with the experimental results by using FOLS along with designed actuator and present the possibility of developing the sensing elements for measuring temperature in the desired range and for use in a diverse range of environments. (C) 2019 Elsevier B.V. All rights reserved.