Single-mode fibre-optic magnetometer with DC bias field stabilization

A sensitive dc field magnetometer, based on magnetostrictive straining of optical fibers is demonstrated, which utilizes active bias field stabilization to ensure that the magnetostrictive sensing element is maintained in a state of zero magnetization. This technique eliminates any problems arising due to magnetic hysteresis effects of the magnetostrictive material which affect the magnetometer output when operated in a conventional 'open-loop' mode. Detection sensitivities of the order of8 \times 10^{-5}A . m-1(\sim10^{-16}Oe), and a linear dynamic range of 105are demonstrated.