An All-Fiber Optic Current Sensor Based on Ferrofluids and Multimode Interference

In this paper, an all-fiber optical current sensor based on ferrofluids and a singlemode-multimode-singlemode structure (SMS) with a piece of no-core fiber as the multimode section was proposed and experimentally investigated. The transmittance of the SMS that is sealed in a capillary with ferrofluids is highly sensitive to the surrounding magnetic field. Because the strength of the magnetic field is proportional to the current in the electric line, so the current can be measured. A demonstration sensor was fabricated and experimentally characterized. A sensitivity of 2.12 dB/A was achieved.