Study On Key Techniques Of High Speed Optical Time Division Multiplexing System

Optical time-division multiplexing (OTDM) and dense wavelength dividion multiplexing (DWDM) are two main technologies of increasing capacity of optical communication system. They can be used to achieve next generation high-speed and large-capicity optical communication networks. This dissertation is supported by the key projects of National Natural Science Fondation "Research on polarization mode dispersion (PMD) compensation and related infrastructure technologies in high speed optical communication systems " and National High-Tech Research and Development Program of China "Study on key technologies in 160Gbit/s OTDM transmission system using multi-fiber pump". In this dissertation, key technologies in OTDM system are investigated, i.e. novel optical modulation formats, ultra-short pulse source, optical time division multiplexer, dispersion, intra-channel nonlinear effects, clock recovery and demultiplexing. The main innovative achievements are listed as follows:(1) Robust narrow fiber bragg grating (NFBG) is fabricated by a kind of stress-tuable equipment, and lOGbit/s vestigial sideband return-zero (VSB-RZ) is obtained. The transmission of and RZ over 155km signal mode fiber (SMF) is accomplished in all-optical experimental WDM network. The results show that the VSB-RZ is feasible.(2) A theoretical model of OTDM based on low repetition rate pulse source is established. The influence of extinction ratio, optical signal to noise ratio of 10GHz pulse source and non-ideal performance of optial time division multiplexer on the 160Gbit/s OTDM signal is analyzed. This is helpful for the optimization and elevation of OTDM tramsimssion system.(3) The effects of dipersion, intra-channel cross phase modulation (IXPM) and intra-channel four-wave mixing (IFWM) on transmission performace of single 160Gbit/s signal are analyzed. The experiment of dispersion and dispersion slope compensation is accomplished.(4) Two methods for simultaneous demultiplexing and clock recovery are proposed:(a) demultiplexing and recovery feed-back loop formed by two tandem EAMs and lOGbit/s clock data recovery unit (CDRU); (b) demultiplexing and recovery feed-back loop formed by EAM,40 Gbit/s electrical time division demultiplexer and clock recovery model. Experimental results prove that these two methods can recover the clock signal successfully and the structures are simple and economic.(5) The experimental transmission system of 160Gbit/s OTDM over 100km is established, the power penalty is 3.5 dB when bit error rate is 10-9. The transmission experiments of 2×80Gbit/s and 2×160Gbit/s optical polarization/time division multiplexing are accomplished, the power penalty are 0.6 dB and 1.5dB when bit error rate is 10-6, respectively.