Optimization Of The Optical Fiber Acoustic Emission Detection System

In the field of acoustic emission testing, optical fiber sensing technology was a lot ofattention for its unique advantages, especially in a variety of single-mode fiber interferometer.With further researching,“Polarization-induced fading” and “Phase shift-caused fading”phenomenon limits the optical fiber acoustic emission sensor to their further application.Therefore, we must find some techniques of dynamic compensation technology forpolarization fading and phase shift to improve system sensitivity.After introducing the basics of polarized light theory, the output intensity formula of thesingle-mode fiber Mach-Zehnder interferometer was overturned when the birefrigent effectexists, and we gave an analysis of its impact parameter based on MATLAB. The polarizationmodulation mechanism, reasons of polarization instability in the single-mode fiber and sometechniques of dynamic compensation technology were introduced also. Afterwards, the outputintensity formula of the single-mode fiber Mach-Zehnder interferometer was overturned whenignoring polarization, and gave an analysis of its impact parameter based on SIMULINK. Theprinciple of orthogonal bias, phase modulation mechanism, the DC phase-tracking detectionmethod and the principle of phase compensation based on PZT were introduced briefly. Inorder to improve the sensitivity and stability of the fiber-optic acoustic emission sensingsystem, some key issues are described, such as the choice of the light, interferometer andpolarization control structure. We used an automatic mechanical device for polarization fadingbased on optical fiber twist in our experiments, and gave detailed instructions of the circuitcalled PZT phase compensation when a small signal was detected. At the end of the paper,four experimental programs are designed which are manual or automatic polarization control,and manual or automatic phase compensation. The results showed that the systemperformance is optimized.