Detection of DC and low-frequency AC magnetic fields using an all single-mode fibre magnetometer

A technique for the determination of weak DC and low-frequency AC magnetic fields using a single-mode-fibre magnetometer is described. The technique utilises the dependence between the AC responsitivity and bias field to detect small changes in the bias field. Detection sensitivities in the milli-gauss/metre region have been obtained using a bulk nickel magnetostrictive element with microgauss sensitivities predicted for certain types of metallic glass.