Investigation On Transmission Characteristics Of Polarization-Division-Multiplexed Differential Quadrature Phase-shifted Keying Signals

As the emergence and spread of many new technologies, such as the mobile Internet, FTTH and the Internet of Things, the existing optical transport networks can not meet the expanding information needs. Nowadays, 100Gbps and above single-channel high speed, large capacity and long-distance optical transmission system has become the trend of future development. However, the traditional OOK modulation format is limited by its own characteristics, and cannot meet the needs of future high speed transport systems. In this context, kinds of advanced modulation formats arise, and have attracted the attention of researchers all around the world. Among all these advanced modulation formats, the polarization-division-multiplexed differential quadrature phase-shifted keying (PDM-DQPSK) has now become the most potential modulation format in the next generation optical transport systems due to its own many advantages.On the basis of reading lots of relevant literature, the theory, simulation and experimental research of the PDM-DQPSK modulation format have been carried out. And the main content is listed as follows:(1) Combined with the latest literature, the research progress of the PDM-DQPSK is reviewed. And the basic theory of optical modulation techniques and polarized light are described. The generation and demodulation of the PDM-DQPSK signals are highlighted. And different representation methods of state of polarization are compared here.(2) The impact of polarization mode dispersion and polarization dependent loss on the PDM signals are studied and analyzed theoretically. And the randomness of the signals'polarization is increased by the PMD effect, meanwhile, the polarization orthogonality is destroyed by the PDL effect. Both of them can increase the difficulty of polarization demultiplexing.(3) Based on VPI software, the transmission characteristics of both time aligned and interleaved PDM-DQPSK signals are researched under the separate and simultaneous impact of different transmission impairments such as chromatic dispersion, PMD and nonlinear effects. Both single- and multiple-channel are studied. And results show that the time-interleaved signals fit for long distance transmission more better due to its high tolerance of nonlinear effects. On the basis of these simulations, the link parameters of single-channel PDM-DQPSK transmission system such as CD and nonlinear effect are optimal designed. And the system performance is greatly improved.(4) Finally, the transmission characteristics of both time aligned and interleaved PDM-DPSK signals is researched experimentally. And the relationship between the RF spectrum of polarization demultiplexed signals and the demultiplexed results is verified experimentally. The result provides a basis for polarization tracking technology.