Paralleled Structure-Based String-Type Fiber Bragg Grating Acceleration Sensor

This paper has presented a novel string-type fiber Bragg grating (FBG) acceleration sensor based on directly utilizing the transversal vibrational property of a tightly suspended optical fiber. This sensor mainly consists of a mass fixed on the middle of an optical fiber embedded with an FBG element and another optical fiber or metal beam in a parallel arrangement mode, which enables to enhance the impact resistance and resonant frequency of the sensor. Compared with existing FBG-based vibration sensors, the proposed sensor possesses an excellent repeatability using a simple structure, and avoids the FBG-pasting process and the associated limitations of chirping failure. The working principle of the proposed FBG vibration sensors with two different configurations has been built with considering the rotational interference of the mass. Static experiments have been completed to show that the sensitivity of the two configurations with paralleled optical fiber and metal beam is 193.6 and 3.275 pm/g, respectively. The paralleled metal beam-based vibration sensor has a working bandwidth of 12 similar to 250 Hz, much larger than that of 4 similar to 28 Hz for the paralleled string-type optical fiber configuration. The performance of the proposed acceleration sensor can be easily adjusted by arranging different types of the parallel structure and modifying their corresponding physical parameters to satisfy different vibration measurement requirements.