Magnetic field sensing via acoustic sensing fibers with submicron magnetostrictive cladding inclusions

Magnetic sensing optical fiber is a recently sought after technology able to withstand harsh environments, capable of distributive sensing, and readily adapted to different magnetic field strengths. A multi material optical fiber system utilizing magnetostrictive nanowires embedded in the fiber cladding was designed, tested, and characterized. The sensor takes advantage of fiber Bragg gratings and magnetostriction induced strain to sense changes in magnetic field amplitude. The distributed optical fiber sensor was shown to detect AC magnetic field strengths as low as 260 mu T while still being able to be fusion spliced despite containing ferromagnetic material inside the fiber. Experiments using nickel and galfenol nanowires contained within the optical fiber sensor were conducted to demonstrate different available sensing ranges for the fiber. The results showed good feasibility for an adaptable fiber design and easy integration to available optical sensing interrogation systems.