Sensitivity-enhanced FBG demodulation system with multi-sideband filtering method

A multi-sideband filtering demodulation scheme with enhanced high sensitivity was proposed to demodulate weak fiber Bragg grating signals, and a novel data processing method was employed to reduce the influence of the background noise. The relationship of the sensing sensitivity, number of sidebands, and their slope coefficients were researched theoretically, numerically, and experimentally. The results showed that the sensing sensitivity was in proportion to the number of the sidebands and their slope coefficients. The power sensitivities for single and double CWDMs demodulating FBG in the experimental system were 6.960 dB/nm and 15.187 dB/nm, respectively, which were in agreement with the theoretical results. In addition, the data processing method we used to obtain the optical power was experimentally proven to be better than the method of directly measuring the optical power because it reduces the background noise.