Multiplexing of fiber Bragg grating sensors using subcarrier intensity modulation

We report the theory and experimental demonstration of two multiplexing schemes for addressing fiber grating sensor arrays consisting of multiple branches. In the first scheme, light in each branch is intensity modulated at different subcarrier frequencies and signals from different branches are separated in frequency domain by using bandpass filters. In the second scheme, the modulation frequency in each branch can be the same and signal separation is performed in time domain by using an electronic switch after photodetection.