Research On Optical Add/Drop Multiplexer Based On Fiber Grating

With the rapid development of optical communication networks,optical add/drop multiplexer(OADM)plays an important role in optical networks because of its polarization independence,low insertion loss,and low cost.Based on the research of fiber grating,two types of optical add/drop multiplexers are designed in this paper.One is based on fiber grating and circulator,and the OADM of three different structures of this type is simulated and studied.The results show that the OADM of the three structures has low loss,low crosstalk and good performance.The other is based on fiber grating,combined with mode division multiplexing(MDM)technology,an OAMD which is based on fiber grating mode division multiplexing is studied,which can realize the upload/download of dual-wavelength three-mode.The main tasks completed are as follows:(1)The basic principle and common structures of OADM are studied and analyzed.The development process,application and tuning technology of fiber grating are expounded.The theoretical analysis of fiber grating is carried out by using coupled mode method and transfer matrix method,and the spectral characteristics of fiber Bragg grating are studied and analyzed by Matlab.(2)Three kinds of tunable OADM based on fiber Bragg grating(FBG)and circulator are proposed,and the spectrum of each port is simulated by OptiSystem when the three structures are operating at full load and under full load.The first kind of OADM has a simple structure and low loss;the second kind of OADM has a complex structure,but greatly reduces the signal crosstalk,and the tuning process of fiber grating will not affect the spectrum at output;the structure of third OADM is simple,flexible,and controllable,and all the four upload/download ports can upload/download different wavelength signals.(3)Based on FBG and circulator,combined with MDM technology,a new type of OADM based on fiber grating mode division multiplexing is studied.Its upload/download capacity is six times that of single-wavelength single-mode OADM,which greatly improves the upload/download capability of OADM.