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 demodulator with a temperature-independent property and a dual head FBG sensor with a temperature-discriminating property. This technique guarantees a stable measurement independent of temperature perturbation at both sides of sensor and demodulator without any additional temperature-isolation or temperature-referencing process and has the minimum resolvable strain of 10 μstrain. The ranges of operating temperature at the sensor and at the demodulator which guarantee a dynamic range of 1800 μstrain corresponding to the wavelength difference 2.2 nm between two notches of the tilted FBG spectrum are from room temperature to 180/spl deg/C and 140/spl deg/C, respectively.