A Long Period Grating Sensor Based on Microtaper Eccentric Core Fiber

A long period fiber grating (LPFG) sensor based on microtaper eccentric core fiber (MTECF) for curvature/liquid-level sensing is proposed and demonstrated. The microtaper modulates the refractive index of the cladding and core of the fiber periodically, and forms a LPFG based on the eccentric fiber. Because the eccentric core of the fiber is off the axis of the fiber, bend and liquid-level measurements cause strong changes in the coupling energy between the cladding and the core, which makes the MTECF structure be suitable for liquid-level and vector curvature measurements. Experimental results show that the bending sensitivities of the sensor are 15.35 and –14.76 nm/m−1 at the bending directions of 0° and 180°, respectively, and the liquid-level sensitivity is 6580pm/mm. The temperature crosstalk of bend and liquid level are 0.012 m−1/°C and 0.0028 mm/°C, respectively.