Preliminary Study on the Stability of High-resolution π-phase Shift FBG Ocean Temperature Sensor

Abstract

Abstract Fiber Bragg gratings are widely used in sensing fields, but few studies about their stability have been reported. A high-resolution π-phase shift FBG (π-FBG) ocean temperature sensor is experimentally demonstrated by using a linearized optical frequency sweeping interrogation system. A gas absorption line from H13C14N (HCN) gas was used to calibrate the laser frequency in real-time, providing long-term stability of the demodulation system. The temperature coefficient of π-FBG is ~14pm/°C, the temperature-resolution is as high as 0.001 °C and the response time is 49.45ms. In order to study the stability of the π-FBG probe, it is placed in a Gallium point bottle with a constant temperature point. Over the course of 4 hours of continuous testing, the probe exhibited a linear drift of approximately 0.09°C.