Lossy Magnetic Fluid-Encapsulated Optical Fiber Magnetometer: Nickel Substitution Effects

A simple and compact highly sensitive optical fiber magnetometer is proposed and experimentally established using nickel substituted magnetic fluids as the sensing nano-materials. The as-prepared samples of nickel substituted magnetic fluids were characterized by using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) for structural evaluation and vibration sample magnetometer (VSM) for assessing the magnetic properties. The synthesizing soft-magnetic composition by suitable doping of nickel into the magnetic fluid applied as the cladding of the polymer optical fiber. A desirable high sensitivity the structure manifested to the action of magnetic field in the measured transmission power. The comparative sensing experiments were implemented with incorporating different compositions of magnetic-fluid formulated as Ni
_x
Fe
_3-x
O
₄
for x=0, 0.1, 0.3, 0.5 suspended in kerosene. The obtained results demonstrated an enhanced magneto induced tunability of the refractive index in the sensing region and this leads to the exhibition of a stronger variation of output intensity loss or recording a higher sensitivity. The magnetic field sensitivities of -0.123 (μ W/mT) and -0.07 (μ W/mT) were achieved in the range of 2.5-50 mT and 60-125 mT, respectively, with linearity more than 99.3% for sample containing x=0.3 nickel.