Research On Efficient And Flexible Multiplexing Communication Technologies For 100gbit/s Passive Optical Network

Information transmission technology is developing rapidly in modern society.With the emergence of new generation broadband multimedia services such as ultra-high network-video conferencing,cloud computing/storage,and virtual reality applications,the bandwidth demand of access network is increasing by an order of magnitude on average every 5 years and is currently moving towards 100 Gbit/s capacity.Traditional time-division multiplexing(TDM)passive optical networks can not meet the needs of high-speed bandwidth.Wavelength division multiplexing(WDM)and space division multiplexing(SDM)technology are favored by domestic and foreign research institutions and operators due to their capable of high-speed transmission advantages.From the practical development of the existing 100Gbit/s passive optical network systems,there are still some key technical problems that need to be solved in the WDM and SDM,inclu ding integrated Add/Drop multiplexing module,design of flexible multi-wavelength source,optical network unit(ONU)colorless,and design and optimization of efficient and flexible system architecture.In this paper,some key technologies of WDM-SDM-PON systems are studied.The goal is to meet the requirements of future access network,realizing high-speed transmission,flexible wavelength management,efficient and integrated architecture.The details are discussed as follows:Due to the low integration of Add/Drop multiplexing module,a highefficiency integrated Add/Drop multiplexing method based on silicon photonic devices is proposed.At the same time,the issue that the traditional integrated device is sensitive to the polarization state of th e input light is solved.The characteristics of transmission and polarization-independent of silicon polarization diversity microring resonator are studied,and the wavelength division multiplexing experiment is demonstrated,successfully realizing the pol arization insensitive integrated Add/Drop multiplexing function.This method is beneficial to achieve efficient integration of WDM-SDM-PON systems.With the bulky size and difficult wavelength management caused by multiple laser sources in the optical line terminals(OLTs)side,a flexible and efficient optical frequency comb method based on electro-optical modulation and selfphase modulation is proposed.The experimental platform is demonstrated by using continuous laser,cascaded electro-optic modulator and dispersion-flattened highly nonlinear fiber.For the generated frequency comb,the center wavelength can be tuned from 1535 nm to 1564 nm,the frequency spa cing can be adjusted from 25 GHz to 40 GHz,and the 30 d B bandwidth is up to 164 nm.The frequency comb can be used to effectively reduce the amount of lasers and enable flexible wavelength management.The method is beneficial for simplifying the architect ure and improving the flexibility of wavelength configuration of WDM-SDM-PON systems.Due to the low spectral efficiency,limited transmission capacity and weak anti-Rayleigh backscattering noise in the current colorless ONU method,a highefficiency and flexible ONU colorless method based on low inter-core crosstalk characteristics of multi-core fiber is proposed.One of the core of the multi-core fiber is used as a dedicated channel,and the optical carrier from the OLT is transmitted to the ONU as a seed light source to realize a laserless,colorless ONU.All the wavelengths of the system are controlled by OLT,improving the flexibility of the optical network.The experimental research is carried out by using four lasers and low inter-core crosstalk seven-core fiber.The results show that the proposed method can effectively avoid Rayleigh backscattering noise,significantly increase the transmission capacity and improve the flexibility of wavelength configuration of WDM-SDM-PON systems.Finally,based on the above research work,a simple,flexible and efficient WDM-SDM-PON system scheme is proposed.By using narrow-band direct-tuning laser,Polar-D micro-ring resonator and multi-core fiber,the experimental platform of WDM-SDM-PON system is demonstrated,and 100Gbit/s high-speed transmission is successfully realized.Thanks to the spectrum shaping characteristic of the Polar-D micro-ring resonator,the extinction ratio of the signal is effectively enhanced.The system applies a simple intensity modulated and directly detection method,and the upstream and downstream signals are bidirectionally transmitted in a multi-core fiber,simplifying the structure and improving the optical network configuration.