Research On Crosstalk Characteristics In Mesh-based Optical Networks-on-chip With WDM

With the promotion of nanotechnology and the silicon-based optical devices which are compatible with complementary metal oxide semiconductor technology,the number of integrated transistors on a single chip has increased sharply to billions and even more to achieve more powerful features.As a result,multiprocessor systems-on-chip(MPSo Cs)as a new trend appear in the commercial application markets,such as multimedia appliances,medical instruments,etc.In order to efficiently interconnect every processor and achieve high performance in MPSo Cs,optical networks-on-chip(ONo Cs)have attracted more and more attention for their strengths of lower crosstalk,lower latency and power dissipation compared to the traditional metal interconnects,and it eventually becomes the most promising candidate in MPSo Cs.In addition,with the rapid development of communication technology,the amount of communication data increases sharply,which leads to larger communication bandwidth and higher computing performance requirements.Although conventional ONo Cs with single wavelength transmission have a great improvement on communication bandwidth,it is still difficult to meet the bandwidth demand for ultra large-capacity high-speed transmission.The wavelength division multiplexing(WDM)technology can effectively improve the communication bandwidth through concurrent transmission of multiple optical signals in a single waveguide.As a result,some researchers have employed WDM technology in ONo Cs to meet the requirements of large scale communication between multiple cores.The study show that WDM-based ONo Cs is one of the key technologies in the next generation optical communication system and large data center for information exchange.Therefore,WDM-based ONo Cs have been pursued deeply by numerous scholars,and they have the potential to be widely used in MPSo Cs and optical communications.The WDM-based ONo Cs are virtually constructed by silicon-based photonic devices according to certain design criteria.However,due to the material properties of optical devices and its manufacturing process,WDM-based ONo Cs inevitably suffer from power loss and intrinsic crosstalk noise.Especially,crosstalk accumulation in ONo Cs is the key factor which restrics the network's performance improvement.Compared to the traditional ONo Cs with single wavelength transmission,WDM-based ONo Cs can be more susceptible to the influence of the crosstalk noise,especially the nonlinear noise generated by the nonlinear four-wave mixing(FWM)effect.The crosstalk accumulation in WDM-based ONo Cs can result in performance degradation,signal distortion,communication quality reduction,optical signal-to-noise ratio(OSNR)attention,and constrain the scalability of the WDM-based ONo Cs.Therefore,this paper focused on the crosstalk analysis and proposed a formal systematical analysis model in WDM-based mesh-based ONo Cs.We also have established a theoretical model and analysis system to provide a reliable theoretical basis and technical support for the next generation of on-chip optical communication system.The main contents of this paper are as follows:First of all,the related theories and techniques of WDM-based ONo Cs based on crosstalk characteristic were studied,including silicon waveguide and SOI microring resonator,optical WDM technology and nonlinear four-wave mixing(FWM)effect.We also have established an analysis model for FWM crosstalk noise in this part.Secondly,based on the working principle of silicon-based optical devices with WDM,a new on-chip switch element with multiple ports,low crosstalk and low loss was designed,the optical router and mesh-based ONo Cs with WDM were constructed respectively.We also have established a crosstalk characteristic analysis model in WDM-based mesh-based ONo Cs performing at device,router and network levels.The analysis model include insertion loss,crosstalk noise,OSNR and bit error rate(BER).Finally,we have exploited a simulation example which employed WDM-based optimized crossbar(WDM-Op.crossbar)optical router and WDM-based Crux(WDM-Crux)optical router in mesh-based ONo CS.We also systematically analyzed and compared the performance of mesh-based ONo Cs using those two optical routers,such as loss,crosstalk noise,OSNR and BER performance in in the worst case,and the corresponding simulation results are given in detail.Furthmore,we have set up a multichannel transmission system on-chip based on Optisystem simulation environment to demonstrate the feasibility of the proposed method in this paper.The simulation results show that both the conventional linear crosstalk noise and nonlinear FWM crosstalk noise are the critical elements for the performance improvement of WDM-based ONo Cs,the crosstalk noise constrain the scalability of the WDM-based ONo Cs.Besides,the optical devices and optical routers with good performance are the key factors for the optical interconnection network.For example,the input power is 1 m W in the worst case,when the size of mesh-based ONo Cs using WDM-Op.crossbar optical router is 4?4,the average power loss,average FWM noise power,average linear noise power and average OSNR are respectively-31.31 d Bm,-37.61 d Bm,-38.86 d Bm and 4.26 d B,and these values are-49.28 d Bm,-37.78 d Bm,-38.95 d Bm and-13.65 d B when the scale of network is 6?6.Obviously,with the network size from 4?4 to 6?6,the network's performance drops sharply.However,when the size of mesh-based ONo Cs using WDM-base Crux optical router is 4?4,the average OSNR in the worst case is 12.37 d B,which is 8.11 d B higher than those using WDM-based optimized crossbar optical router.And when the scale of network is 6?6,the average OSNR in the worst case is-1.37 d B,which is 12.28 d B higher than using WDM-based optimized crossbar optical router.