Research On Eliminating Light Intensity Disturbance In The Fiber-Optic Sensor Based On PGC Demodulation Algorithms

Interferometric fiber optic sensor has many advantages over other types of sensors,such as high resolution,high sensitivity,high sensitivity,low cost,and anti-electromagnetic interference.Therefore,in recent years,the interferometric fiber optic sensor gets many attention,and it is widely used in many engineering applications,such as the safety monitoring of building structure,detection of oil pipeline leakage and intrusion detection.The phase generated carrier(PGC)modulation demodulation technology is the most widely used in interferometric fiber optic sensor.Compared with other types of demodulation technology,the method has good linearity,wide dynamic range,strong anti-interference ability,and avoiding the phase shift.However,the traditional PGC demodulation algorithm based on differential cross multiplication(PGC-DCM)is vulnerable to the influence of light intensity,so that the demodulation results are not stable when the output of the light source is unstable or the polarization fading in the optical fiber transmission.And the traditional demodulation algorithm based on Arctan(PGC-Arctan)can eliminate the influence of the intensity of the demodulation results.But it is related with the depth of modulation,and it is easy to produce harmonic distortion.Based on PGC modulation and demodulation technology,two kinds of PGC improved demodulation algorithm are proposed,which can effectively eliminate the influence of the intensity of the interference and improve the stability of the interference fiber optic sensing system,so it has a very good application value.The main contents of this paper are as following:Firstly,a PGC demodulation algorithm based on the reference compensation is proposed in the paper.In this algorithm,a reference signal is introduced to estimate the intensity disturbance,then the test signal is compensated by the variance reference signal.Then I simulating it with MATLAB software,and verify it correction.Secondly,a PGC algorithm using an asymmetric processing is used to eliminate the influence of light intensity disturbance.The improved algorithm can eliminate the influence of light intensity disturbance by using multiplying-over-square.The validity of the method is verified by MATLAB simulation.Thirdly,the improved algorithm is verified by the related experiments,and the two cascaded Mach-Zehnder interferometer is built.The first interferometer is used as a light intensity modulator,and the second interferometer is used to measure the signal.The output light intensity of the second interferometer is received and demodulated by the photoelectric detector,and the improved PGC demodulation algorithms is verified.