Analysis of the channel crosstalk in multiplexing system of the fiber laser sensors

Abstract

Due to the limit of the channel isolation in the TDM system or the WDM system, the crosstalk usually exists between the fiber laser sensors in the multiplexing system. In this paper, the relationship between the channel crosstalk and the channel isolation is investigated. By means of studying on the phase generated carrier (PGC) demodulation and the passive homodyne demodulation based on the 3×3 coupler, which are usually used in the fiber laser sensor system, the crosstalk between two channels were discussed separately. The output mathematic models of the demodulation system were analyzed, when the sensing channel including the leak laser from the other channel. The mathematic models were set up used for theoretical analyses of the non-coherent crosstalk between two channels in the system, and the mathematic models show that the channel crosstalk between the two channels have relation to the power of the leak laser and have a slowly varying random factor which represents an environmentally induced variation. The acoustic sensing experiment shows that the models are suitable to calculate the crosstalk between two channels of the fiber laser sensor in the multiplexing system. In the acoustic sensing experiment, the channel crosstalk of the experiment is -18.7 dB, and the channel crosstalk should be -19.36 dB according to the mathematic models.