A study of fiber Bragg grating as a temperature sensor

Abstract

Fiber Bragg gratings (FBGs) became one of the elegant sensor components for static and dynamic parameter measurement, for instances, temperature, strain and pressure. FBGs are based on the principle of Bragg reflection. Their Bragg wavelength shift is proportional to the temperature and strain variations which are experienced by gratings. In this study, a fiber Bragg grating sensor is proposed to detect the temperature on the surface of mechanical structures. In particular, we point out that the method is well suited for measuring very small temperature because they are able to withstand in a high temperature environments, where standard thermocouple methods are failed. The sensing principle is based on tracking of Bragg wavelength shifts caused by the temperature change. In this work, fiber grating is dipped into partially filled water breaker that place on a hotplate for the heating process. The Bragg wavelength shifts are observed using optical spectrum analyzer (OSA). The sensitivity of this sensor due to temperature variations is 0.0138 nm/°C almost equal to common FBG. The correlation of theoretical calculations and experimental results show the capability and feasibility of the purposed techniques. It will be useful for monitoring the flow allocation on production wells, fire detection, steel building, tunnels, leak detection and temperature monitoring of reactor vessels, flare stacks, power line. Therefore, it is expected that the fiber Bragg grating sensor, because of its uniqueness in many aspects and being at an affordable cost, has an excellent propect in temperature measurements.