Intensity-type vibration sensor based on multiple subchannels sensing scheme

A novel intensity-type vibration sensor using multiple phase-shifted fiber Bragg grating (MPS-FBG) pair is proposed to improve vibration sensitivity of a system interrogated by broadband source. The enhanced vibration sensitivity compared to normal FBG is accomplished by the increased of total intensity change produced by multiple subchannels operation. Significant vibration sensitivity enhancement has been achieved compared to the normal FBG in experiment (e.g. nearly 20 dB using 17 phase shifted FBG), which agrees with the theoretical expectation. The improved sensitivity of the proposed scheme would be highly desirable for cost effective wavelength multiplexed vibration sensing system based on single broadband source.