Study of a novel demodulation method for FBG sensor

A novel demodulation method for Fiber Bragg Grating (FBG) sensor based on matching grating demodulation is proposed. It is means using several fiber gratings to cascade, and programming to make the computer automatically select different wavelengths. So that it can expand demodulation range based on high sensitivity. The photoelectric detector (PD) makes the reflected light intensity which form FBG change into voltage. And the voltage is amplified to 0 similar to 5v by amplifying circuit. Then through the data collection box, voltage sent to computer for data acquiring. Real-time analysis data and display the variable of center wavelength for sensing FBG. Because the same type of sensing FBG and demodulation FBG, they have the same temperature drift, so it can control the influence of environmental temperature. Therefore, this system can successfully solve the temperature/strain cross-sensitivity issue. The experimental results show that it is feasible to demodulate wavelength using the cascaded FBG. And the experimental measuring wavelength error is less than 0.009 nm, the measuring micro-strain error is less than 7.5 mu epsilon.