High sensitivity magnetic field sensor based on a Mach-Zehnder interferometer and magnetic fluid

An intensity modulation optical fiber magnetic field sensor based on MZI and magnetic fluid is proposed and demonstrated. The MZI is composed of a no core fiber-thin core fiber-no core fiber (NTN) structure and the cladding of thin core fiber is etched by hydrofluoric acid. The fiber structure is immersed in magnetic fluid. The sensitivity of the etched device is 5.3 times that of the non-etched device. The maximum sensitivity of magnetic field intensity achieved in our experiment as high as 0.563 dB/Oe. Meanwhile, the fringe visibility achieved 30.78 dB. This device has the advantages of convenient manufacture, small volume and high sensitivity. It has application potential in the field of magnetic field sensing.