Incident-power-dependent refractive index of ferrofluid in magnetic field measured with a fiber optic probe

Abstract Using the Fresnel reflection geometry and a fiber optic probe, a strong effect of interrogating light intensity on an effective refractive index of ferrofluid placed in magnetic field was observed and measured. With a moderate level of light power from 0.5 mW to 135 mW, an effective refractive index of kerosene-based ferrofluid was increasing with rising of light power by more than 4% at the same strength of magnetic field. It is important to note, no such dependence was observed without magnetic field applied. Also, influence of light power on dynamics of optical response on magnetic field impulse was observed.