Fiber-optic magnetic field sensor using magnetic fluid as the cladding

A kind of fiber-optic magnetic field sensor is proposed. The sensing structure is composed of singlemode-multimode-singlemode fiber structure cascaded with core-offset fusion splicing between singlemode fibers. The sensing principle is based on the cladding mode interference. Experimental results indicate that, the magnetic field sensing sensitivities of 65.9 pm/Oe and 0.1185 dB/Oe are obtained for wavelength interrogation and intensity interrogation, respectively. The corresponding measurement range of magnetic field strength is 30-110 Oe. The response of temperature is also investigated. The corresponding temperature sensitivities for the interference dip around 1594 nm is obtained to be −42 pm/°C and −0.124 dB/°C.