TEMPERATURE-INDEPENDENT STRAIN SENSOR SYSTEM USING A TILTED FIBER BRAGG GRATING DEMODULATOR

We experimentally demonstrate a new approach for the demodulation of a fiber Bragg grating (FBG) strain sensor by combining a tilted FBG dem odulator with a temperature-independent property and a dual head FBG s ensor with a temperature-discriminating property. This technique guara ntees a stable measurement independent of temperature perturbation at both sides of sensor and demodulator without any additional temperatur e-isolation or temperature-referencing process and has the minimum res olvable strain of 10 mu strain. The ranges of operating temperature at the sensor and at the demodulator which guarantee a dynamic range of 1800 mu strain corresponding to the wavelength difference 2.2 nm betwe en two notches of the tilted FBG spectrum are from room temperature to 180 degrees C and 140 degrees C, respectively.