Enhanced FBG strain sensing multiplexing capacity using combination of intensity and wavelength dual-coding technique

A novel concept for interrogating a fiber Bragg grating sensor array using intensity and wavelength dual-coded multiplexing (IWDM) is proposed and evaluated. In comparison with conventional wavelength-division-multiplexed sensor systems, IWDM allows the number of sensing gratings in an array to be doubled without sacrificing dynamic range and without additional cost or complexity of interrogation. A practical strain sensing system based on IWDM and using specifically produced gratings with a dual-peaked spectral response has been demonstrated with 50-Hz interrogation rate and 1 /spl mu//spl epsiv/ resolution.