An all-fiber current sensor based on magnetic fluid clad microfiber knot resonator

A novel optical current sensor based on microfiber knot resonator (MKR) with magnetic fluid (MF) as cladding is proposed and demonstrated in this paper. The operating principles, package technique and mounting method of the proposed sensor are introduced in detail. Moreover, the performances of the proposed sensor are demonstrated experimentally by detecting sinusoidal current with 50Hz and pulse current signals with rising time of 2.5μs respectively. The results have shown that the relationship between the sensor responding and the applied current intensity is approximately linear and the minimal detectable current is 10 Amps with SNR (Signal-to-noise ratio) as 3.