Improved spectral tag method for FBG sensor multiplexing with equally spaced spectral codes and simulated annealing algorithm

We propose a multiplexing scheme for an FBG sensor system on the basis of wavelength division multiplexing (WDM). Each double grating sensor is assigned with a unique spectral tag of two different Bragg wavelengths. The simulated annealing algorithm was employed for the demultiplexing procedure of identifying spectral peaks in the measured reflection spectrum of the FBG sensor system. The peak detection accuracy was as good as 0.6 pm for overlapped spectral peaks in the simulated reflection spectrum. An array of four FBG strain sensors was tested experimentally and the maximum measurement error was 9.1 ¿¿.