Research On Chromatic Dispersion Estimation Algorithm In High Speed Optical Fiber Communication System

With the rapid development of video live,mobile Internet,big data and Internet of things,the data traffic in the network presents the characteristics of continuous growth and the optical fiber communication is also developing towards the ultra-high speed,ultra-long distance and ultra-large capacity.Therefore,the physical damage introduced by the optical signal in the transmission process is becoming more and more serious to the degradation of the optical fiber communication system performance.In order to ensure the stable and reliable operation of optical communication system,the optical performance monitoring(OPM)of the transmission link must be carried out in order to grasp the operating state of the system in real time.With the increase of the speed of the optical fiber communication system,the CD tolerance decreases sharply.Therefore,it is particularly important to monitor the dispersion in optical fiber link quickly and accurately.In this paper,the basic principle of coherent optical communication,the physical damage of optical fiber links and optical performance monitoring technology are analyzed theoretically.On this basis,the CD estimation algorithm in high-speed optical fiber communication system is deeply studied.The main research contents and results are as follows:1.Firstly,the mechanism of CD effect on optical communication system is deduced theoretically.The research status and development direction of CD estimation algorithm are investigated and the typical CD estimation algorithms are analyzed.2.The CD estimation algorithm based on auto-correlation function of signal power waveform is deeply analyzed,and the relationship between the autocorrelation function and the CD of optical fiber link is deduced theoretically.The simulation platform of the coherent optical transmission system is built,and the performance of the CD estimation algorithm is analyzed for different modulation formats and different noises.On this basis,an accurate CD estimation algorithm based on Chirp Z transform is proposed,and the algorithm is analyzed theoretically and verified by simulation.3.The CD estimation algorithm based on heterodyne detection is proposed,the relationship between the heterodyne detection signal and the accumulated CD of optical fiber link is derived theoretically.The simulation system of coherent optical communication with different modulation formats is built to verify the feasibility of the proposed algorithm.Simulation results show that the CD estimation algorithm based on heterodyne detection has high estimation accuracy.In addition,it has good robustness to amplifier spontaneous emission noise,laser phase noise and nonlinear effect of optical fiber.