Key Technologies Research On Optical Performance Monitoring In Few-Mode Fiber Communication Systems

At present,a new round of global scientific and technological revolution and industrial transformation with information technology is booming,and information network infrastructure construction has become its top priority.As the core of information network infrastructure,the mode-division-multiplexing optical fiber communication system possess an irreplaceable importance.In this paper,we present a new method of inter-mode dispersion monitoring in the few mode fiber link and an overall monitoring scheme of optical performance in the reconfigurable all-optical multi-granularity optical network.Firstly,a nonlinear phenomenon in the few-mode fiber,namely the four-wave mixing effect,is theoretically analyzed.The few-mode nonlinear Schr?dinger equations with two spatial modes are derived,different forms of multi-mode non-linear Schr?dinger equation(MM-NLSE)for two is derived,along with up to types of wave/mode distributions and their corresponding phase matching conditions.Inspired by the principle of inter-mode four-wave mixing,an inter-mode dispersion monitoring method is proposed,which can monitor the inter-mode dispersion of the few-mode fiber link,which is real-time,simple and reliable.The 16 QAM few-mode fiber transmission system was designed by the simulation software Optisystem 7.0,and the simulation results of the dispersion monitoring system were analyzed for the few-mode fiber link.Secondly,for the MG-OXC can sample the specified single optical wavelength channel easily,we propose a method for overall monitoring of the performance of digital optical communication signals in mode-division-multiplexing multi-granularity traffic switching all-optical network directly.By configuring an eye diagram test unit or an eye diagram test instrument on the all-optical network optical node,the performance the power,signal-to-noise ratio,time jittering,and degree of nonlinear crosstalk degradation of the WDM optical wavelength channel can be monitored comprehensively.The method is transparent to signal protocol and bit rates and is able to distinguish between different optical impairments.This paper focuses on the above two key technical issues concerning the transmission chain of few-mode fiber,and provides technical support for the large-scale application of MG-OXC system based on few-mode fiber.