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 of
8 \times 10^{-5}
A . m
^-1
(
\sim10^{-16}
Oe), and a linear dynamic range of 10
⁵
are demonstrated.