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, cross-sensitivity 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 plusmn1 mA can be obtained within the whole range from 0 to 400 mA, vibration measurement are also obtained based on the present experiment setup.