Research On The FBG Sensor Used In Detecting The Underwater Sound Signal

Along with fiber optic industry rising promptly in our country and with the improving of technology in production, fiber optic grating(FBG) had become one of the most successful optic passive device. The FBG sensor has a series of prominent superiority , and it meets the advancing of performance arm and equipment working in water of navy. So it is very important to use FBG in detecting the sound signal in water. This work begins under such background.FBG sensing mechanism is presented exhaustively, the advantage and disadvantage of a few demodulation scheme in common use is introduced. Based on the analyzing of sensing mechanism, we make deep research on how to stabilize the work point phase of the M-Z fiber optic interferometric in order to detect the echo wavelength shift of the FBG. Therefore, the scheme is brought forward and the simulating is completed on computer, it is proved that the scheme is correct.At last, we design a scheme to demodulate the wavelength modulation by using optical circulator and Michelson interferometric with Faraday rotator mirror. The signal fading induced by random fluctuations in the states of olarization (SOPs) of the interferometric beam and random excursion of the work point of interferometric is overcome, and the SNR of signal is improved. Based on it, we probe to put forward a time-devision multiplexing FBG sensor array. The detecting scheme by using interferometric we brought forward posses innovate significance in domestic fiber optic hydrophone research area at present, and it have more practical value.