A Novel Demodulation Method for the Sagnac Interferometric Fiber Current Sensor

The principle of all Fiber-Optical Current Transducer (AFOCT) was introduced. By analyzing the characteristic of photodetector's output signal, a novel demodulation scheme based on sine wave modulation was put forward, eliminating the effects induced by the change of light source power and modulation depth . The measurement principle, processing method, and the thought of related circuit were also discussed. The delay, caused by data processing, was reduced to less than 50μs, improving the response speed of the total system. The experimental data show that the correlation coefficient is up to 0.998714.