Study On Supermode Characteristics Regulation Mechanism In Multicore Microstructure Fibers

With the continuous development of society,current communication technology is increasingly difficult to meet the growing demand for communication capacity.As a new generation of transmission media,optical fibers have a rapid development owing to their large communication capacity.Multicore microstructure fibers have a rapid development in recent years,because of their novel light-conducting mechanism and excellent properties of the fundamental supermode.Multicore microstructure fibers have widely used in the fiber communication system,fiber lasers,fiber devices and fiber sensing.In this paper,the issues of number of supermodes,dispersion and effective mode area,supermodes interference in multicore fibers are studied,respectively.Firstly,the research background and significance of multicore microstructure fibers are introduced.Simutaneously,the numerical simulation methods used in this thesis are briefly expounded.Secondly,the multi-pole method,finite element method and coupled mode theory are used to study the number of supermodes in multicore microstructure fibers.The coupling effect between the cores and the influence of the cladding on the number of supermodes were studied respectively.According to the coupling mode theory,the coupling matrix is used to study the number of supermodes.The equivalent cladding index is obtained by the effective refractive index method to study the coupling cut off situations of the higher order supermodes.Thirdly,based on the characteristics of the effective refractive index of the supermodes are modulated by mode coupling mechanism as well as the influences of the geometrical parameters on the mode area and dispersion,the multicore microstructure fibers with single supermode transmission,large mode area and flattened dispersion are studied.Finally,a dual-core single-polarized splitter based on supermode interference effect is designed.By using dual core filled liquid crystal and high geometric birefringence,the supermodes in one polarization direction are coupled with the fundamental space filling mode,and only the odd and even supermodes in the other polarization direction are obtained.There is a constant phase difference between the two supermodes,which leads to the interference effect.Therefore,the wavelengths at 1310 nm and 1550 nm can be splitted.