| In recent years,along with the rapid development of multimedia business,network business and broadband integrated services digital network,all Optical communication has become a target for the development of Optical communication.To improve the capacity and transmission performance of optical communication system successively,there has put forward the concept of OCDMA(Optical Code Division Multiple Access).This thesis operated the research and simulation analysis for the coherent OCDMA system mainly.Firstly this thesis investigated present situation and the development of optical communication and several mainstream multiplexing and addressing technology.Then the thesis analyzed and compared properties of OWDM(Optical Wavelength Division Multiplexing),OTDM(Optical Time Division Multiplexing)and OCDMA.The research status of OCDMA system experiments and codec technology was also summarized.Thesis analyzed the theory of the coherent OCDMA coding/decoding system.Through the simulation software OptiSystem,the thesis built three kinds of systems such as the one-dimensional OCDMA system based on optical fiber delay line or optical fiber Bragg grating and the twodimensional OCDMA system based on the above two.After that,thesis operated the experimental research simulation for these three systems and implement the data transmission of two users at 4Gbit/s.Experimental results show that bit error rate of one-dimensional system is lower,but user capacity of the two-dimensional system is greater and the confidentiality is higher.To improve the performance of the system,this thesis discussed the effect of optical fiber grating reflection spectrum width and selection of wavelength to the performance of incoherent OCDMA system.On the basis of the result of discussion,this thesis designed the tunable optical fiber Bragg grating applicable to two-dimensional incoherent OCDMA system with the software OptiGrating using the temperature characteristic of optical fiber Bragg grating. |
