Analysis on the Influence of SLD's Optical Power on the Performance of Fiber Optic Current Transformer

As one of the core components of fiber optic current transformer (FOCT), the optical source has a crucial influence on the performance of FOCT. Super luminescent Diode (SLD) is an ideal optical source for FOCT because of its high output power, low coherence and wide spectrum. However, in the long-term operation process, the output optical power attenuation of SLD is inevitable. Based on the first-order system model of FOCT with closed-loop control, the influence model of SLD's output optical power on the key performance of FOCT is established. The influence of optical power attenuation on the measurement error, measurement bandwidth, output signal-to-noise ratio (SNR) and step response of FOCT is simulated and analyzed. The simulation results show that the optical power attenuation of SLD is the main influence factor the phase error of FOCT, and the central wavelength drift caused by optical power attenuation is the key influence factor the FOCT ratio error. In order to meet the technical requirements of current transformer level 0.2, the optical power attenuation of SLD should not exceed 10%. The simulation analysis results have guiding significance for putting forward a reasonable method to stabilize the output optical power of SLD and improving the long-term reliable operation performance of FOCT.