High frequency current sensing using optical fiber micro-wire

Fiber-optic current sensors exploiting the Faraday effect have attracted a great deal of interest due to their wide dynamic range, robustness and remote sensing capability. Recently a new approach to current sensing using optical fiber micro-wire (OFM) with 5 µm diameter in the configuration of a micro-coil (MC) has been proposed and successfully demonstrated [1]. It featured high compactness, robustness, configurability and excellent confinement of light and was able to demonstrate its ability to sense currents with a 1 µs rise time. In this paper we present a major improvement in the current sensing bandwidth, demonstrating a capability to detect a fast current pulse with pulse width (full width at half maximum: FWHM) of 6.7 ns.