Simultaneous measurement of temperature and bend by using an eccentric core fiber Bragg grating cascaded with a Fabry-Perot cavity

Abstract

A simultaneous temperature and bend sensor based on an eccentric core fiber Bragg grating (ECFBG) cascaded with a Fabry-Perot cavity is presented and demonstrated. The hybrid structure is composed of a piece of hollow core fiber, which is sandwiched in between a piece of multimode fiber and an ECFBG. The curvature sensitivities of the ECFBG at the two opposite most sensitive directions are 52.2 pm/m⁻¹ and −51.7 pm/m⁻¹ respectively, and those of the FPI are 58.6pm/m⁻¹ and −61.4 pm/m⁻¹, respectively. The temperature sensitivities of the two parts are very different. The temperature sensitivity of the ECFBG is 10.3 pm/°c, and that of the FPI is as low as 0.7 pm/°c.