Effect Of The Spectral Width Of Optical Sources Upon The Output Of An Optical Current Sensor

Optical current sensors (OCSs) are the kind of devices that directly or indirectly realize the transformation or measurement of current in order to achieve the sensing of the current. The substitution of OCS for the current-transforming techniques based on electromagnetic induction is a revolutionary evolution in the techniques of current measurement and power line protection in the industry of power delivery. This paper focuses on the effect of spectral width of the optical source on the output of Bulk Glass Optical Current Sensor (BGOCS). The work is significant in both theory and engineering applications.The optical source employed in the BGOCS is a super luminescent diode (SLD), which is a broad-band optical source. Based on the technical document and the measured power spectral distribution, Gauss distribution model is employed to approximate the real source. Consequently, the amplitude distribution is also a Gauss distribution. SLD is a low coherent optical source, its total intensity equals to the summation or the integral of every wavelength intensity component. The wavelength accumulation theory is based on this principle. With the parameters varies within the range of our study, the simulation results compared with their corresponding monochromatic output show that: the wavelength accumulation effect upon the output is small; therefore, it is reasonable and feasible to employing the monochromatic model to deal with the BGOCS systems with broad-band source; the difference between the accumulation output and the monochromatic output decreases with the increase of the current to be measured in the total wavelength accumulation effect; the effect of the Verdet constant is the greatest, that of the Reflection-Induced-Retardance (RIR) is intermediate, that of the linear birefringence (LB) is the smallest.As the spectral width (Full width half maximum: FWHM) range from 6nm to 60nm, the simulation results show that the effect of the variation of the FWHM upon the output is small. When only the Verdet constant is considered, the output increased slowly with the increase of the FWHM. The simulation results are verified by the experiment.