Multi-point interrogation of FBG sensors using cascaded flexible wavelength-division Sagnac loop filters.

A simple optical signal demodulation technique is demonstrated for multi-point interrogation of fiber Bragg grating sensors. The wavelength-division responses of polarization-maintaining fiber Sagnac loop filters are flexibly controlled to interrogate the simultaneous optical intensity changes from the independent wavelength shifts of multiple fiber Bragg grating sensors. Experimental performance is also demonstrated to show the simultaneous detection of the separated FBG sensing signals by individual photo detectors.