Fiber optic magnetic field sensor based on the TbDyFe rod

We present, and experimentally demonstrate, a fiber optic magnetic field sensor for the measurement of a weak alternating magnetic field, based on a TbDyFe rod. The fiber optic magnetic field sensor is constructed in a Michelson interferometer configuration, and the phase-generated carrier demodulation is used to obtain the time-varying phase shift induced by the applied magnetic field. A high sensitivity of up to 3.6×10^-2VμT^-1 (rms) with a resolution of 23pT/√Hz (rms) at 50Hz is achieved. Experimental results show that the sensor exhibits excellent linearity and reversibility.