Optimisation of signal-to-noise ratio in an optical current measurement system using different detection schemes

The comparative performance of two alternative detection schemes used in an optical current measurement system are simulated and theoretically analyzed. An appropriate experimental arrangement is constructed to measure and compare the signal-to-noise (S/N) ratio obtained for these two detection schemes under conditions of the same level of noise being induced. Both simulated and experimental results show that the sensitivity and the signal-to-noise ratio of an optical current measurement system varies with the changing of the detection scheme and the cross-polarisation angle between the polariser and analyser, The highest sensitivity and the largest signal-to-noise ratio are obtained when using differential detection and a 45° cross-polarisation angle. These positive results suggest that such systems may find wider application in current sensing