The Research Of An Optical Fiber Spectrum Intensity Modulation Direct Detection Transmission System

Time-Lens has drawn significant research interesting for many years owing to its wideapplications; especially all optical time-frequency real time Fourier transforms.The principle of the time-frequency real time Fourier transforms with the space-lens isgiven at the beginning. By comparison, the principle of the time-frequency Fouriertransforms with the time-lens can be obtained. There are two kinds of structures toimplement the time-frequency Fourier transforms, the―dispersive medium+phasemodulator+dispersive medium (D-PM-D)‖structure and the―phase modulator+dispersivemedium+phase modulator (PM-D-PM)‖structure. Considering advantages at thetransmission speed in high speed optical communication systems, the second structure isapplied in this thesis. Then, LiNbO3phase modulators, which can be used to implement thetime-lens, and dispersive mediums are applied to construct two kinds of optical fiberspectrum transmission systems. One is to use the time-frequency Fourier transformsstructure both at the transmitter and the receiver. The other is only at the receiver. The bestsystem parameters of different situations can be obtained according to the simulation resultsby VPI（VPItransmissionMaker）simulation software. And the BER performance of theIM-DD (Intensity Modulation Direct Detection) system with time-frequency Fouriertransforms structure is much better than the traditional IM-DD system at40Gb/s and100Gb/s.Furthermore, a―Pulse Reverse‖(which means the order of the pulse sequence isreversed) method based on the time-frequency Fourier transforms structure is presented. Thismethod can be applied in all optical logic fields and all optical information processing.At last, a novel coding method is presented to reduce the peak power of the optical pulesin optical fiber spectrum transmission systems. According to theoretical calculations andsimulations, conclusions can be drawn that the novel coding method is able to reduce thepeek power as well as the impact of the optical fiber’s nonlinear effect. It can also improvethe system performance.