Design And Research Of A Kind Of Dispersion Compensator Used In The WDM System

The technology of dispersion compensation is one of the crucial technologies in the realm of optical fiber communication. Because of the appearance of Erbium Doped Fiber Amplifier (EDFA), the problem of optical fiber loss has been solved basically. Then people's attention is more and more concentrating on the research of the optical fiber communication system which is limited by optical fiber dispersion instead of that which is limited by optical fiber loss. At the same time, because of the strongly competitive ability and characteristic predominance of Wavelength Division Multiplexing (WDM) technologies and "bottle neck" limitation of Time Division Multiplexing (TDM) technologies, people's interest is transferred from the TDM to the WDM. The WDM technologies are developing rapidly and are used widely. So how to settle the problem, in which dispersion is accumulated in WDM system, becomes a focus of study.hi accordance with the physical principle of dispersion generation, many kinds of technologies of dispersion compensation have been researched and expounded. For instance, dispersion compensation fiber technology, pre-chirpped technology, dispersion supported transmission technology, chirpped fiber grating technology, and so on. But the study of dispersion compensation technology in which the dispersion of the optical signal in every channel in the WDM system is compensated respectively is reported rarely.In this paper, on the basis of increasingly mature fabrication technologies of planar integrated waveguide and the optical fiber grating, we make use of not onlythe (de)multiplexing and wavelength router characteristic of Arrayed Waveguide Grating(AWG), but also the dispersion peculiarity of Uniform Fiber Bragg Grating(UFBG). Then a kind of dispersion compensator, which can compensate the dispersion of the optic signal in every channel in the WDM system respectively, is devised. The method makes the compensation efficiency maximum theoretically.In this article, at first, the dispersion conception and generation reason are explained, and the dispersion influences that are brought about in the analog and digital signal transmission in optical fiber communication are accounted for. Next, the dispersion theory of optical fiber is discussed in detail and several useful technologies of dispersion compensation are introduced. Then, after the structure and characteristic of AWG is described in brief, we put emphasis on the deduce of the dispersion equation of UFBGS in the vicinity of its reflection band gap(RBG) in light of coupling theory. In terms of this equation, the dispersion compensation of the optical signal in every channel in the WDM system, which has eight channels, is calculated and analyzed theoretically. During the course, some important parameters of UFBGS in the compensator are computed. Finally, the result manifests that it is necessary that the dispersion of the optical signal in every channel in the WDM system be compensated respectively. By use of the compensator, which is designed here, the dispersion efficiency can obtain very high value. The realistic possibility of fabricating this compensator is mentioned in this paper.