Study On A New Demodulation Method Of Maher-zendl Interferometer

With the development of science,optical fiber sensor is more and more widely used in people's life.Fiber optic mach-zehnder interferometer(MZI)is a kind of functional fiber optic sensor,which has the advantages of simple structure,stable mechanical performance and high accuracy with measurement,playing an important role in the field of modern sensing.The optical signal interfered after passing two 1x2 couplers,and the measured signal would cause the phase changing of the interferometric signal.After the optical signal is converted into an electrical signal which is easy to be observed and measured,the phase difference between the two is compared through the detection,amplification and modulation of the electrical signal,and the size of the signal to be measured is obtained.Therefore,how to demodulate to measured accurately and efficiently has been one of the core problem of MZI.In this paper,I analyzed and studied,the phase demodulation method of MZI,and designed a simple,accurate and efficient demodulation system.In terms of the content distribution,this paper first analyzes the traditional method of the mach-zehnder interferometer and the principle of the traditional fiber optic phase modulation and demodulation,compares the advantages and disadvantages of various methods,and proposes the overall scheme of the system.Then the design scheme is constructed in detail,the characteristics and requirements of each module are put forwarded,the reasons for choosing chips and circuit designing are analyzed in the selection of components,and the specific circuit diagram of circuit design is given.Finally,on the basis of module selection,a phase sensing demodulation system based on balanced m-z interferometer is built,and the phase demodulation experiment is carried out.The experiment shows that,in an normal operating conditions,when the optical signal of 1310 nm wavelength is interfered in m-z interferometer,the phase change of the interference signal is approximately linear with the size of the interfered signal,and the phase detector needs 0.0131429v(about 13.1mv)for every 1° move,which is consistent with the result of theoretical analysis.It indicates that it is feasible to monitor,demonstrate and demodulate the interference signal by this demodulation method,and the desired accuracy can be achieved.The method has high precision and good stability,so that the phase detection work can accurately detect the phase change without the period limit,and the detection range is easy to control,only related to the coherence length.This has certain positive significance for the development of optical fiber research in the future.