Experimental Study of Coupling Fiber-optic Vibration Sensor Based on Variational Theory

According to the character of fiber-optic coupler, its coupling output is sensitive to the variation of coupling region's length. A new kind of coupling fiber-optic vibration sensor is presented base on this principle. The theory of coupling single-mode fiber-optic sensor is analyzed. A prototype of fiber optic vibration detection system has been successfully built, including a sensor head, a low-cost control unit and a software package for signal processing with high resolution. The response of fiber-optic sensor and piezoelectric sensor to periodic vibration and shock is measured and the results of the coupling fiber-optic vibration sensor are closely in accordance with high precision piezoelectric sensor. The cross-axis anti-disturbance ability of the fiber-optic sensor is discussed in addition. Experimental results indicate that the coupling fiber-optic vibration sensor has favorable vibration detection capability; it can meet the requirement of vibration measurement.