Fiber grating sensor array interrogation with time-delayed sampling of a wavelength-scanned fiber laser

A novel method for fiber Bragg grating (FBG) sensor array interrogation based on a wavelength-scanned fiber laser is presented. The wavelength of the scanning fiber laser is monitored by time-delayed sampling and assigned to return peaks as Bragg wavelengths of the sensor gratings. From experiments with an array of four FBG sensors, the scheme showed the same measurement results using different wavelength scanning waveforms, which verified that this scheme demodulated the sensor signals linearly, regardless of nonlinearities in the wavelength-tuning mechanism. Overall, ∼20 pm of measurement accuracy was obtained which could have been greatly enhanced with faster phase modulation.