Multi-level Phase Modulation Formats And Their Polarization Mode Dispersion Performance In High Speed Fiber-optics Communication System

Recently, fiber-optics communication system is upgrading towards high speed and large capacity. With the speed increcement of backbone network, chromatic dispersion, nonilearity and polarization mode dispersion of fiber can not be ignored any more. Kinds of new modulation formats are proposed. At the same time, compensation for polarization mode dispersion is essential in hig-speed system. Besides, with the development of PolMux system and coherent system, receivers require polarization stabilization device. New modulation formats, adaptive polarization mode dispersion compensator and a novel polarization stabilization scheme are analyzed in this paper. The research works in the dissertation are summarized as follows (innovative works are labled in bold):Modulation technology of optical signal is reviewed; Mach-Zehnder modulator which is extensively used in optical modulation is analyzed; characteristic of time and frequency domain for DQPSK modulation format is analyzed both via theoretical and simulation, including constellation, phase diagram, eyediagram and spectrum of different duty-cycle signals.The basic concept of polarization state of optical signal and polarization mode dispersion of fiber are reviewed; optical compensation method is discussed in detail.The principle of 8-DPSK modulation format is analyzed via theoretical and simulation, including constellation, phase diagram, eyediagram and spectrum of different duty-cycle signals; Moreover, the polarization mode dispersion compensation performance of 8-DPSK is studied.Novel modulation formats of dual-polarization DPSK and dual-polarization DQPSK are analyzed both via theoretical and simulation, including constellation, phase diagram, eyediagram and spectrum of different duty-cycle signals; performance of polarization mode dispersion (PMD) is analyzed by using Jones Martrix method; besides, dual-polarization DPSK sigal is obtained via experiment for the first time.The achievements of adaptive polarization mode dispersion compensator for DPSK and DQPSK sigals are verified via experiment; we obtain relationship between feedback signal DOP and main component of polarization mode dispersion DGD; DOP map of DQPSK signal is achieved.A novel polarization stabilization scheme is proposed, which can transform input signal into any desired output polarization state; performance of the polarization stabilizer is verified via experiment, with the center processing unit of computer and DSP system, separately.