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.