The Research And Implementation Of PMD On-line Monitoring System

With the rapid development of high-speed and large capacity optical fiber communication system, polarization mode dispersion (PMD) has become one of main obstacles of the future high-speed optical fiber communication system. Polarization mode dispersion may become the ultimate limiting factor of the fiber transmission capacity. To solve this problem, this paper focused on the basic theory of polarization mode dispersion. Basing on this, we made a thorough research on measurement of polarization mode dispersion and on-line monitoring system. And then we proposed new measurement and monitoring programs of the PMD compensation.In this paper, we firstly made a presentation of the background, significance and research of polarization mode dispersion. After fully describing in its importance, we studied the basic theory of polarization mode dispersion, including birefringence, polarization mode coupling, statistical properties and so on. This made the theoretical foundation for the later research of measurement of polarization mode dispersion.The second part of this paper is the analysis and research of the PMD measurement methods and monitoring systems. We researched and discussed interferometry, Jones matrix and Miller matrix method, the fixed analyzer method, Poincare sphere method, pulse delay measurement method. Then we analyzed and summarized the advantages and disadvantages of these programs. After these, the paper focuses on the research of the on-line monitoring program. Comparing of the existing program, we know the PMD on-line monitoring program based on Stokes parameters is the most practical one. Then we made a comprehensive description to this program from three aspects, theoretical design, feasibility analysis and technical difficulties.Based on the various PMD measurement programs, this paper presented a very suitable site for online testing program, single-ended measurements. The advantages of this program are convenient field test, distributed measurements, providing the evolution of PMD and so on. It has good prospects for development.The last part of this paper is the research of PMD compensation using fiber Bragg grating. We used a innovative method of gluing the fiber grating to the thin aluminum, which has a larger thermal expansion coefficient. Then the fiber grating chirp was enhanced by the temperature control. And it would be converted to nonlinear birefringence chirped fiber grating. Through the study of its properties, we can prove the feasibility of this program. Finally, we made functions expansion based on this system. This novel dispersion compensator has two operating modes, tuning dispersion without central wavelength detuning and tuning central wavelength without dispersion detuning.