The Fiber-Wireless Sensor System for Temperature Monitoring Using Sagnac-Loop Interferometer

Abstract

In this paper the proposal of fiber-wireless monitoring network with power-modulated Sagnac loop based temperature sensor setup is presented. The temperature fiber optic sensor consists of polarization-maintaining fiber (PMF) in a Sagnac loop. Due to known properties of Sagnac-loop sensors, the shift of interferometer spectrum is observed in a function of temperature. In this case, the idea is to use a short length of PMF within Sagnac-loop, which implies wide separation of interferometer dips. As a result of such an approach, the various spectral characteristics are observed for different temperatures. This is equivalent to different detected optical power at the output of proposed sensor. Instead of usage of high-cost and complex spectral analysis devices, the presented novel fiber optic sensor setup operates on mapping optical power (output voltage) to given ambient temperature. The experimental measurement was performed for temperature in a range of 21 – 50 °C. Additionally, the proposal of fiber-wireless sensor system based on integration of fiber optic sensor with ZigBee transmission.