Research On The Output Performance Of ALL-Fiber Mach-Zehnder Interferometer

Optical filter is an indispensable component in optical communication and photoelectron fields. It has been widely used in wavelength locking, wavelength multiplexer/demultiplexer, wavelength routers, dispersion compensators, and gain equalizers etc. With the increasing number of channels and decreasing channel spacing in wavelength division multiplexing (WDM) system, novel optical filters with excellent characteristics have become a leading trend presently. Particularly, the Mach-Zehnder Interferometers (MZIs) have attracted considerable attention in the WDM system, because of their excellent characteristics, such as simple structure, low insertion loss, multi-level series, comb and band-pass filtering etc.First, based on the Jones matrix theory, strict theoretical analysis is taken on the output characteristics of MZI. MATLAB simulation is taken to discuss the effect of the coupling ratio, the length of arms, and the index of refraction to the output characteristics of MZI. In order to improve the extinction ratio, a fiber reflector is added to the end of interferometer, and by this way, the MZI can get a high extinction ratio interferometer. After adding the reflector, the extinction ratio of it increases 21dB or so. When changing the fiber reflector for a fiber Bragg grating (FBG) the MZI become to a single channel switch. Secondly, the output of cascaded MZIs is studied and the influence of cascade to the interferometer is also analyzed. A new algorithm which is called GA is proposed to analyze the cascaded MZIs. A new Multi-channel filter is designed the frequency spacing of which is below 100GHz. Compared the new method to the ideal way and transfer matrix analysis method, the GA algorithm is close to the ideal way. Finally, a new OADM model based on MZI is designed and analyzed. In order to design the new OADM FBGs are added to the arms of MZI, the improved OADM is also designed. Whether the design is right or not the function of the new OADM is validated by the software Optiwave. The emulation shows that the design is perfect.The result of the research of the paper show that the cascaded MZIs and the optical components based on MZIs will be found many potential applications in the fields of WDM system.