A simple fiber-optic current sensor using a long-period fiber grating inscribed on a polarization-maintaining fiber as a sensor demodulator

We propose a simple fiber-optic current sensor based on the Faraday rotation effect, which firstly utilizes a fiber-compatible polarization analyzer as a sensor demodulator. The fiber polarization analyzer (demodulator) was fabricated by inscribing a long-period fiber grating on a polarization-maintaining fiber. The manufactured fiber polarization analyzer has the polarization extinction ratio of more than 25 dB at the fixed wavelength of 1522.5 nm. Current sensing up to 600 A rms was demonstrated in a simple and cost-effective way, showing a good linearity.