Study And Realization Of2.5G Long-span Repeaterless SP&DP Coherent Optical Communication System

With the rapid development of Internet service including video conference as well as mediastreaming and the resulting explosive amount of internet traffic has posed pressure to existingoptical backbone infrastructure. Optical transmission cables usually pass through harshenvironmental conditions in large amount of applications. Therefore the maintenance of relaystation would be quite difficult. Optical transmission system with longer span distance and lessrelay stations is of great importance. There has been an ever-increasing interest of bothacademic and industrial on ultra-long distance transmission systems beyond400km. Theultra-long span repeaterless optical transmission system has been a great promote of moderninformation society.A polarization division multiplexed quadrature phase shift keying (PDM-QPSK) basedcoherent repeaterless optical communication system is proposed and studied both theoreticallyand experimentally. Compared with traditional IM/DD technique, the high detectionsensitivity of coherent detection method is well favorable on long-span repeaterlesstransmission system in which the Signal noise ratio (SNR) of optical light is rather limit after aextremely long transmission. Thus the transmission span can be increased utilizing coherentdetection method.In this thesis, the performance of2.5Gbps long-span repeaterless PDM-QPSK coherentoptical transmission system is studied and realized on an FPGA platform. At first, theperformance of the system is evaluated and the algorithms employed is studied and optimizedthoroughly based on the off-line platform. Then all the algorithms for the system is optimizedand implemented on an FPGA platform. At last, the coherent repeaterless optical transmissionsystem is analyzed theoretically for a higher capacity and longer transmission span.