USING FIBER BRAGG GRATINGS WITHIN OPTICAL FIBER SENSORS TO DETECT MAGNETIC FIELDS FOR THE DEVELOPMENT OF SMART STRUCTURES

A magneto-optic coupling for smart structure sensors is trying to be achieved by using Fiber Bragg Gratings (FBGs) within optical fibers. Fiber Bragg Gratings are one type of optic fiber sensors that have been mounted onto structures in order to obtain stress/strain data allowing structural health monitoring in real time. These Bragg Gratings are essentially “walls” that are printed onto the core of the optical fibers by passing ultraviolet light onto the fiber during manufacturing. When a signal is sent through the fiber, a resonating wavelength bounces back (Bragg Wavelength, λ_B) from these gratings. If a load is applied along the axis of the fiber, it suffers an axial stress and thus an axial strain, which can be detected by noting linear shifts in the resonant Bragg Wavelength. By creating an optic fiber that consists of a glass doped with ferromagnetic nanoparticles, a direct interaction between the magnetized nanoparticles and the light passing through the fiber can be observed under the presence of nearby magnetic fields. This allows the sensor to have a dual-functionality: monitor the overall structural health in which the sensor is mounted and detect nearby magnetic signatures for strategic maneuvering. Applications for this type of sensor can range from civilian automobiles to military aircrafts.