The Study Of In-Band Optical Signal-To-Noise Ratio Monitoring Based On Polarization

With a wide range of popularity of the Internet in recent years, and a great demand of traffic load from application services, end users requires the transmission capacity to have an explosive growth. With the development of optical networks and related technologies, the optical network based transport networks become more complex, more intelligent, which increased the difficulty of optical network management.In order to have real-time quality control of the transmitted signal, make the appropriate adjustment of the entire optical network and let the whole optical network be manageable and controllable, optical performance monitoring technology came into being. Optical signal to noise ratio is one of the most basic parameters of optical signal, which is directly related to the terminal bit error ratio, and is not limited to the signal rate and modulation format etc., especially suits for dynamic reconfigurable optical networks, for all those reasons it is often used as one of the most important criteria during optical signal performance evaluation. The setup, optimization, warning, analysis of optical networks are related to OSNR as well.This paper is mainly about OSNR monitoring. The main work is as follows:1. Analysis and discussion of the advantages and disadvantages of the mainstream monitoring methods. Matlab simulation platforms are built For typical monitoring methods, such as linear interpolation method and polarization-nulling method, pointing out its monitoring range and monitoring accuracy, and effects of other physical damage such as polarization mode dispersion on the specific monitoring methods are also been analyzed.2. Proposed a novel OSNR monitoring method based on polarization interference, theoretical formula are derived and analyzed o prove the feasibility of this method, and a Matlab simulation platform is built to further validate the method. Simulation results of the monitoring method shows to guarantee the monitoring accuracy of+/-0.5dB the monitoring range is from9dB to34dB. What’s more, the method is testified to be transparent to both bit rate and modulation format, and independent of both polarization mode dispersion and chromatic dispersion, the tolerance of PDL is also analyzed;3. Proposed an OSNR monitoring method of distribution of signal Stokes parameters on Poincare sphere, by a Matlab simulation platform the relationship between real OSNR and the EVM distribution of signal Stokes parameters is showed, and the monitoring range at different monitoring accuracy is given, the impacts and tolerance of the signal rate, PMD, CD, etc. are also analyzed.