Research On Suppression Techniques Of Chromatic Dispersion In High-speed Optical Fiber Communication Coherent Detection System

As the capacity of high-speed optical fiber communication system goes larger and the distance goes longer, the chromatic dispersion of optical links grows up to be one of important performance restriction factors in 40Gb/s and 100Gb/s above systems. The chromatic dispersion compensation and recovery technology based on coherent detection has also been a hot point in the optical communication research field. At the moment, chromatic dispersion compensation filter sulotion in electronic domain is mainly used in coherent detection system, which offers the advantages like larger amount of compensation, better compensation performance, flexible and efficient. While the design of constructure and length parameter of filter will determine compensation performance and application value, so chromatic dispersion compensation algorithms, filter constructure improvement and parameter optimization based on compensation principle are discussed in this paper which are summarized as follows:1. Transmission characteristic of optical links are reviewed; the influence of chromatic dispersion on signal is mainly analyzed, and transmission simulation model of chromatic dispersion and noise are built.2. Coherent receiver’s principle and impariments compensation algorith-ms unit’s constructure are introduced; a 40Gb/s homodyne coherent detection NRZ-DQPSK simulation system is set up, and measuring method of OSNR at receiver is also explained in this paper.3. Two kind of clock recovery algorithms is analyzed in detail, and the direct interpolation-resample method is used to recover experimental data of 25GBaud/s coherent detection PDM-NRZ-QPSK system effectively.4. The time domain FIR digital filter is designed and improved into even-symmetric form with lower complexity, and simulations of compensation performance are completed; the parameter-number of taps which affects filter design complexity is optimized further in order to achieve compromise in performance and complexity. In addition, the method and simulation of compensation in frequency domain are completed.