Optical Performance Monitoring Of Multi-level And Multi-dimensional Signals

With the rapid development of modern society, people’s increasing demands for information. As optical fiber communication has a ultra-high transmission rate, it has become a major channel for information transmission backbone. Gradually toward the next-generation optical network dynamically reconfigurable transparent network transformation, network structure more complex wisdom. After building a large capacity and high efficiency of the transport network, optical network monitoring and management has become a key issue. At the same time, in order to improve the stability of the optical transmission system, the multi-dimensional multi-level modulation format is applied to a growing number of which optical transmission system. Therefore, optical performance monitoring for multi-level multi-dimensional modulation formats (OPM) attracted people’s attention.Based on the above background, the paper focuses on optical performance monitoring of multi-level and multi-dimensional signal modulation format and launched a study, the main works are as follows:Firstly, the current status of the development of optical networks, from the analysis of the needs of the optical network, analyzes the significance of the OPM, and on the scope of OPM, the implementation of an introduction. Analysis of the optical transmission process by injury, and the causes of these injuries and their impact on the system. And from the time domain to the frequency domain analysis of the current perspective of existing optical performance monitoring technology classification and presentation.Secondly, analysis of the current existing modulation formats, including modulation principle, the transmission performance. Analysis Optical 16QAM modulation and coherent demodulation in detail, and the using OptiSystem commercial simulation software, build based on I/Q modulated square type and based De-MZM star type optical 16QAM signals coherent optical transmission systems, transmission rate of 100Gb/s.Finally, considering the pros and cons of each method, we propose optical 16QAM signal performance monitoring technology based on an asynchronous delay-tap sampling technique (DTS). Using OptiSystem built signal modulation system and combination of MATLAB to test and verify DTS optical performance monitoring technology. Simulation results show that the method for square and star 16QAM signal has a relatively good monitoring results. While monitoring a star 16QAM signal, according to changes in the phase diagram defines OSNR factor and dispersion factor, the optical signal to noise ratio in the range of 10～35dB to have a better monitoring results; For dispersion, monitoring range of 0～150s/nm. In monitoring the square 16QAM signal OSNR monitoring can be realized within 13～33dB range, dispersion monitoring within 0～128ps/nm range. And validated for square 16QAM signal OSNR monitor the impact of the dispersion, the simulation results show that the impact of the dispersion factor OSNR mainly in increased base of the slope is not affected; dispersion for OSNR the impact of the greater dispersion value, the lower the OSNR monitor sensitivity.