Research On Format Conversion Based On Non-linear Effect Of Optical Fiber

Electronic communication equipment cannot meet people's needs on speed and bandwidth well because of its restrictions on the input power and logic conversion rate,so researchers have launched the research of optical communication.The format converter is an important communication device in optical communication.Non-return-to-zero codes are suitable for short-range WDM systems because of their short transmission distance and high dispersion tolerance.Return-to-Zero is often used in TDM because of good non-linear tolerance.So,the conversion between NRZ and RZ can realize the communication between WDM and TDM system.In this thesis,four-wave mixing is the core nonlinear effect.Using MATLAB simulation software to achieve the NRZ to RZ format conversion.The main content and results are as follows:(1)Through analyzing optical transmission equation and coupling equation,this thesis focused on the core theory of format conversion which named degenerate FWM.According to this principle,the principle of format conversion is introduced.(2)This thesis designed a photoelectric format conversion device.The simulation experiment can realize the format conversion from optical NRZ to electric RZ.Simultaneously,this thesis used MATLAB to simulate the time domain of the format conversion,frequency domain of the format conversion and eye diagram of the format conversion,and proved the scheme format conversion successfully.The influence of the input pump light power on the RZ signal generated by the format conversion and the influence of the input clock pulse width on the RZ signal generated by the format conversion are analyzed.As well as the simulation is realized after exchange of input pump and NRZ signal position.The results show,input pump and NRZ signal position cannot influence format conversion.The power of the two RZ signals obtained under the electric field will increase when the input pump power increasing.At the same time,the time width of the obtained two RZ signals will increase as the input clock width increases.The entire format conversion device can be run with little input power.The entire conversion rate is 40 Gb/s.(3)This thesis designed an all-optical format conversion scheme based on M-Z interferometer.We completed the simulation from the NRZ to the RZ format conversion simulation in all-optical surroundings successfully.Using the same discussion and analysis as the photoelectric format conversion,a similar conclusion is obtained.Unlike the one above,we can get three RZ signals.In addition,this thesis analyses the impact of XPM and SPM on the conversion process.The research shows that XPM and SPM will cause the incomplete interference,affecting the format conversion.This thesis verified the conversion from 40 Gb/s NRZ to 3*40 Gb/s RZ.(4)This thesis designed an all-optical format conversion scheme based on Sagnac ring.The same analytical method as the M-Z interferometer was used.Compared with M-Z scheme,the scheme has different results.Format conversion cannot be achieved when exchanging the position of the pump and NRZ codes.The interference incomplete phenomenon cannot exist and the format conversion quality is very well.The entire conversion rate is 40 Gb/s.(5)Compared the three format conversion schemes designed in this thesis...