Underwater Magnetic field and temperature sensing with a Michelson-like interferometer of core-offset and FBG

A magnetic field and temperature sensing structure is proposed and investigated experimentally of which the structure is analogous to a Michelson-like interferometer. It is consisting of a core-offset and fiber Bragg grating (FBG) immersed into magnetic fluid (MF), where a large core-offset (around 8μm) and re-coupling cladding modes to the core are excited by the downstream FBG. As the area of the cladding modes indicates the mode intensity, together with and FBG wavelength interrogations, the sensitivities of magnetic field and temperature sensing can be of -0.3427 /mT and 7.34 pm/°C for magnetic field and temperature changes, respectively. The structure is of low-cost, easy-fabrication and applicable flexibility in multi-parameter sensing if a variety of other sensitive materials utilization.