A Model of Magneto—mechano—optical Transfer in Fibre—optic Magnetic Sensors with Magnetostrictive Films

摘要

Fibre—optic magnetic sensors with magnetostrictive films are used as all—fibre Mach—Zehnder interferometer to detect the optical phase shift, which is caused by the magnetostriction—induced strains transferred from the magnetostrictive film to the fibre. A theoretical model based on the plane strain approximation and uniform axial strain is developed to determine the magneto — mechano — optical transfer relations in this kind of sensors. The expression for the model is presented as well as relation of the phase shift in the fibre to the magnetic and elastic properties of the magnetostrictive film coated on the fibre. And from the model, the thickness of the film has significant influence on the phase shift.