Research On New Architecture Of Ultra High Speed And Ultra Large Capacity Optical Fiber Communication System

The architecture of ultra-high speed and ultra-large capacity optical fiber transmission system is the most basic and important engineering technology problem in optical fiber communication.The inevitable trend of transmission rate is to increase the single-wavelength rate to increase the transmission rate of single channel from 40 Gbit/s to 100 Gbit/s or even 1 Tbit/s.The industry needs new system architectures and technologies to achieve the revolutionary improvement of transmission performance and capacity.In view of the above problems,this thesis has carried out a series of theoretical and experimental studies on three main aspects of the new ultra-high speed and ultra-large capacity optical fiber communication system architecture: coherent optical ultra-large capacity optical fiber transmission system architecture,ultra-high speed IM-DD metro system architecture and ultra-large capacity coherent WDM-PON system architecture.How to improve the transmission capacity of single fiber is the most important problem in the coherent optical ultra-large capacity fiber transmission system.As the potential of single-mode fiber transmission capacity is about to be exhausted,in order to improve the transmission capacity,the key technologies of space division multiplexing optical fiber transmission system have become the focus of research in this field.In the aspect of ultra high-speed direct modulation and direct detection metropolitan area network system,with the development and commercialization of PAM-4 modulation format based optical module,how to use the new digital signal processing algorithm to optimize and improve the transmission and reception performance of PAM-4 signal has become a hot issue in academic research.In terms of the architecture of ultra-large capacity coherent WDM-PON system,the simplified coherent structure and the classical coherent structure have their own advantages.It is necessary to study the simplified coherent reception technology in WDM-PON architecture to promote the application of classical coherent reception technology in WDM-PON system.The main achievements and innovations of this thesis are as follows:(1)In view of the characteristics of the ultra-large capacity optical fiber transmission system architecture,DFT-S OFDM is used as the system modulation format to reduce the peak-to-average power ratio(PAPR)of the signal and the nonlinear effects in the optoelectric devices and optical fiber transmission system.Serial experimental demonstrations of ultra-large capacity coherent optical transmission system are realized based on DFT-S OFDM format.(2)In the field of ultra-large capacity space division multiplexing optical fiber transmission system,this thesis propose to use the correlated peak value of synchronous head to evaluate the mode coupling and mode dispersion in the few-mode fiber,which can be used to determine the cyclic prefix length of DFT-S OFDM signal in the few-mode fiber transmission system.In this thesis,the design parameters of several kinds of space division multiplexing fiber are given,and a series of space division multiplexing fiber are designed and fabricated based on these parameters.Based on these SDM fiber,the experiments of 200 Tbit/s DFT-S OFDM 32 QAM optical signal transmission system,560 Tbit/s coherent optical DFT-S OFDM 32 QAM optical signal transmission system and 1.068 Pbit/s coherent optical DFT-S OFDM 16 QAM optical signal transmission system were designed and demonstrated based on these SDM fiber.(3)Dual binary(DB)coded PAM-4 scheme is proposed to compress the frequency spectrum of PAM-4 signal,improve the spectral efficiency and reduce the limitation of dispersion and device bandwidth requirement on the system.A 12-km single-mode optical fiber transmission experiment based on single-channel 112Gbit/s DB-PAM-4 signal is designed and demonstrated.Only one ADC at 50GSa/s sampling rate is used at the receiver side,and the-3d B bandwidth of the system is only 20 GHz.At the PAM-4 signal receiver side,a nonlinear equalization algorithm based on simplified neural network is proposed to improve the performance of PAM-4 signal.An experiment of 4×50 Gbit/s PAM-4 signal over 80-km SSMF transmission based on the neural network algorithm is designed and demonstrated.The performance is improved by 2d B when compared with the common nonlinear equalization algorithm based on Volterra filter.(4)A simplified coherent detection structure is proposed to reduce the cost and complexity of coherent detection system.Then,based on the simplified coherent detection structure or the classical coherent structure,two ultra-large capacity UDWDM-PON system architectures are designed.The proposed coherent optical UDWDM-PON architectures are verified by experiments,which provide useful guidance for the application of coherent optical technology in optical access network.The related paper won the title of top scored paper in OFC2019.