Magneto-elastic-optical coupling of Terfenol-D based optical fiber magnetic field sensors

A magneto-elastic-optical coupling model for Terfenol-D based single-mode optical fibers is proposed, in which the nonlinear magneto-elastic coupling characteristics of Terfenol-D is taken into consideration. The field-dependent material constants for magnetic coating is predicted and in good agreement with experimental results. The coupling effects of external stimuli (e.g. magnetic field and stress) on magneto-optic (MO) coupling coefficient of optical fibers are investigated for the first time. The results show that the relative phase change is enhanced by changing the thickness or Poisson's ratio of constituent materials. More importantly, appropriate applied tensile/compressive stress can control the value of optimal bias field as well as enhance MO coupling coefficient of optical fibers under different magnetic fields. This research provides a method to evaluate and improve magnetic performance of the optical fiber magnetic field sensors consisting of giant magnetostrictive materials.