Research On Dispersion Management In High Speed Soliton Communication System

Optical Communication, which adopts light as its carrier and uses optical fiber as its medium, developed quickly during the past 30 years owing to the characteristic of large information capability, high transmission speed, perfect interference immunity and long relay distance, etc. The widening of pulse width that caused by fiber's dispersion had become a bottleneck for the further development of optical fiber communications. Consequently, dispersion compensation technology became a hot issue. As a special wavelet packet, soliton can maintain its velocity, shape and amplitude during its transmission. Applying these merits to optical communications, and after 30 years'theoretical and experimental research, the conceptions and theories of soliton communication have gradually been formed. Meanwhile, soliton communication technology develops continually because of the improvement of understanding and of the blossom of new technology. During research it has been found that in practical communication environment, there are several obstacles that prevent soliton communication becoming applicable. As an improved technology which appeared in the middle 90s, dispersion management soliton technology is of a great practical potential, and has become one of the most important problem in optical fiber communication field.This dissertation expounds the basic concept of dispersion management (DM) soliton in detail, and studies its application in soliton communications. In view of the barriers of soliton communications in actual communication environment, this paper analyzes the control effects of DM on soliton communications. At first, the general status quo of soliton communication domestic and foreign is expounded in detail. In this foundation the commercialization of soliton communication is discussed in sequence. The transmission of normal pulse in fiber is reviewed and analyzed, including the effects of loss, dispersion and nonlinear on pulse. It has been testified that dispersion mainly broadens the width of the pulse and nonlinear mainly broaden the band-width and self-steepening. In addition, the effect of high order dispersion, high order nonlinear effect, collision between the adjacent solitons and the invite of EDFA is also analyzed. The high order dispersion brings dispersion wave and single sideband vibration, and cause error code. The high order nonlinear effect, such as Raman Effect, can cause self frequency shift. In OTDM system, the collision, which always alters amplitude and position of the pulse, mainly happens between adjacent solitons. The noise introduced by erbium doped fiber amplifier (EDFA) can ultimately cause timing jitter. All the above show that soliton communication must be governed with control technology. Slit Step Fourier is invited to solve the NLSE to get the numerical result. Meanwhile, the evolution equations of the amplitude,central location and frequency can be got with variational method. By the two different methods, this paper proves that the behavior of soliton in practical communication environment can be well controlled by using dispersion management, and the disadvantage of collision between can be alleviated. Comparing with normal soliton communication, it has been testified that high order dispersion can be restrained by using dispersion management method. Thanks to Optisystem, a well known optical simulation tool, this paper analyzes the configuration of dispersion management map. The result is that the best configuration map is the so called symmetry compensation map, under which it gets the clearest eye diagram. In addition, this paper also has a discuss on the three typical dispersion management mode, and based on the above, a novel dispersion management map is brought forward. The simulation shows that the new map performs well in high speed and long distance communication. The shape of pulse and the eye diagram persist well after 4000km. At last, from the point of practical design of dispersion management system, the idiographic design process and method are summarized, and it will helps a lot to the practical engineering application.