Research of a double fiber Bragg gratings vibration sensor with temperature and cross axis insensitive

Abstract

A novel double fiber Bragg gratings (FBGs) vibration sensor with temperature and cross axis insensitive is developed. In order to eliminate the influences of the temperature drift, the symmetrical pull–push structure is adopted. The sensor head is based on two elastic material cylinders, into which two matching FBGs are embedded respectively, loaded with a seismic mass. Closed-form analytical formulas describing the resonant frequency and sensitivity of the FBG vibration sensor are provided which may be utilized to tailor the sensor performance to specific applications. The phase generation carrier (PGC) interrogation technique based on the unbalanced Michelson interferometer is studied. Experimental results of a prototype vibration sensor show that the acceleration sensitivity of the FBG vibration sensor reaches 450pm/g in the frequency range of 5–100Hz. The resonant frequency of the FBG vibration sensor is 210Hz. For a temperature change from 0°C to 50°C, the wavelength shift of the sensor is almost 0 without any temperature compensation schemes. The noise floor of the FBG vibration sensor is obviously improved and reaches −100dB/Hz1/2 over the range of 40–100Hz. The experimental results prove the good performance of the FBG vibration sensor.