Fiber Bragg Grating Sensor with a Simple Demodulation Method

Principle, structure design, and experimental setup of a fiber Bragg grating (FBG) sensor with a simple signal detection method for demodulation of resonance wavelength shift of the FBG are introduced, which uses a cascade self-demodulated fiber Bragg grating pair attached respectively on the upper and lower surface of a pendulum-type cantilever element instead of a twice reflection FBG pair structure for both parameter sensing and wavelength shift signal demodulating. In addition, crosssensitivity effect of FBG-based sensor automatically solved due to a differential signal process method. With this demodulation method, current, and vibration measurement experiments are carried out. Experimental results indicate that current measurement error of ±1mA can be obtained within the whole range from 0 to 400mA, vibration measurement are also obtained based on the present experiment setup. Keywordsfiber Bragg grating sensor; current measurement; gravity pendulum; electromagnetic force