A Compact High Sensitivity Micro-Displacement Sensor Based on a Long-Period Fiber Grating with an Air-Cavity

a compact high sensitivity micro-displacement sensor based on a long-period fiber grating (LPG) with an air-cavity is proposed and experimentally demonstrated. The sensor head is obtained by composing an air-cavity with a LPG and a single mode fiber (SMF). The shift of the wavelength of the LPG is depended on the length of the air gap. The experimental results show that the sensitivity 0.2155nm/μm is achieved within the measurement range of 0 to 140μm at the initial air gap length of about 216μm.