Addressing fiber Bragg grating sensors with wavelength-swept pulse fiber laser and analog electrical switch

A pulse train with a wavelength dependent time sequence is generated in a fiber laser configuration, which contains a cascaded wavelength-division-multiplexing (WDM) fiber Bragg grating (FBG) array and a tunable F-P filter. By distributing pulses to corresponding channels with a 1 × N analog electrical switch, a novel FBG sensors interrogation technique with advantages of high signal-to-noise ratio (SNR) and high interrogation speed is experimentally demonstrated. Then, a FBG sensing system based on this interrogation technique and the mature unbalanced scanning Michelson interferometer (USMI) demodulation technique is realized. The system has shown a sensitivity of 1.610°/με, for the 1555 nm FBG, which agrees well with the theoretical value of 1.674°/με.

Research Highlights
► Cascaded WDM FBG array and an inter-ring F-P filter are used to realize a tunable pulse fiber laser.
► By distributing generated laser pulses, a FBG sensors interrogation technique is demonstrated.
► Apply the technique to 4 elements sensing system the interrogation frequency of 1 KHz is obtained.
► The same system showed a strain sensitivity of 1.610°/με, for the 1555 nm element.