Study On Optical Comb Filters Based On Birefringence

WDM has greatly promoted the development of optical communication. With theincreasing of the channel density in the DWDM system, a new type of optical component‘interleaver’has emerged.In this thesis, several typical realization technologies of interleaver are described andcompared. Based on the birefringence effect, a polarization-dependent birefringent-crystal-based interleaver and a polarization-independent interleaver using the high birefringent fiberSagnac interferometer are presented.The vector of polarized light is given. The Jones matrixes of several main opticalcomponents and transfer functions of the two different kinds of interleavers are developed.Choosing different structural parameters, a large number of simulations are done.The principle of the birefringent-crystal interleaver is analyzed theoretically. Astructureof interleaver with three cascaded birefringent plates is presented, and four functional partsare specifically designed. The parameters of three birefringent plates are given. The filtersperformance is compared with different number of crystal plate. Several problems in thecomponent design are analyzed. Analog birefringence structure is presented to solve theproblem of larger crystal size. The value of polarization dependent loss is calculated and amethod of temperature compensation is put forward.Two high-order HBF Sagnac interferometers (HBFSI) that have flat transmissionspectrum are proposed. Some factors which affected transmission performance of theHBFSI-based interleaver are discussed. Finally, some experiments are done based on thetheoretical research and simulation. The correctness of transmission functions andwavelength interval expressions is verified, and the flattop spectrum is got using thestructure of two-stage Lyot Sagnac interferometer.