Demodulation of a weak fiber Bragg grating array using a fiber delay line

We demonstrate the use of a fiber delay line (FDL) to demodulate a weak fiber Bragg grating (WFBG) array. The FDL is composed of a fiber-ring cavity, by which the delay time is matched with the interval length of the adjacent WFBGs. Two pulses reflected by the former WFBG with delay and a pulse reflected by the rear WFBG without delay overlap and interfere. The emitted sounds can be given by the interference signals of a 5-WFBG array with the FDL. Using the FDL, it is demonstrated that the simple structure can be used to demodulate the WFBG array.