Estudo de sensor de campo magnético baseado em fibra óptica com rede de Bragg e Filme Fino de Terfenol-D

Abstract

Magnetic field measurement has many application from military area, as detection of airplanes, ships and tanks, to electrical generator and transmission system as electric current sensing. Sensors based on optical fiber with thin film technology become great options to this application, once they are electromagnetic imunes, small dimensions and intrinsically electrically insulated. The goal of this work is the production of a magnetic field sensor based on an optical fiber with a Bragg grating inscribed and coated with a Terfenol-D magnetostrictive thin film. When an external magnetic field is applied, the magnetostrictive thin film presents a strain that will be transmitted to the optical fiber. The strain will be detected by the displacement of the wavelength reflected by the Bragg grating. The developed sensor presents a sensitivity of 0.075 pm/mT with operational range of 50 to 150 mT for a field perpendicular to the fiber optical longitudinal axis. In addition to the sensor characterization, a thorough characterization of the thin film was performed, including chemical composition, structure and magneto-optical properties. The final system response was analysed in view of these informations. We also verified the influence of the characterization setup in the sensor response.