Miniature Temperature-Independent Curvature Sensor Based on a Phase-Shifted Long-Period Fiber Grating Using Deep Tapering

A miniature temperature-independent curvature sensor was proposed and prepared by using a phase-shifted long-period fiber grating (LPG) fabricated from deeply tapered conventional single-mode fibers (SMFs). As a typical example, a sensor made from a phase-shifted deeply tapered long-period grating (PS-DTLPG) with a length of 3.4 mm and a maximum curvature sensitivity of 12.05 nm/m(-1) was successfully demonstrated. The proposed curvature sensor is temperature-independent and has features of high sensitivity, high reliability, miniature size, and low cost, which could have potential applications in structural health monitoring, especially for the medical industry and shape reconstruction.