Abstract: Temperature and magnetic field are the two factors which will affect the magnetic fluid refractive index through theoretical analysis. A method with independent sensing probes based on the principle of Fresnel reflection was presented. Experimental measurements were carried out to investigate the relation between the magnetic field intensity and temperature dependent refractive index of the magnetic fluid. The results showed that， for a given concentration of the magnetic fluid， the effect of temperature on nMF was relatively insignificant with a sensitivity of -802×10-5℃-1 under zero magnetic field intensity. When there was an external magnetic field(parallel to the propagation direction of light)， the nMF would increase with the increase of the magnetic field intensity at constant temperature. The repeatable performance of this device was also proved to be perfect. The tunable refractive index characteristics of magnetic fluid could be used as the theoretical basement for filling into the photonic crystal fiber(grating)to achieve a magnetic field and temperature sensing.

Key words: magnetic fluid, refractive index, Fresnel reflection, tunable characteristics, temperature and magnetic field sensing