Analysis And Optimization Of Physical Characteristics Of Optical Networks-on-chip Based On The Minimum Loss Routing Algorithm

With the rapid development of technology and silicon-based photonic technology,the size of transistors is getting smaller and the number of transistors integrated on a single chip is increasing.With the increasing integration of circuits,multiprocessor systems-onchips(MPSo Cs)has emerged and received widespread attention.How to realize efficient interconnection between processing cores is the research focus of MPSo Cs.Network-onchip(No C)is a new communication method,which draws on the knowledge of distributed computing system and uses packet routing for on-chip communication.It overcomes the disadvantages of the traditional bus architecture of MPSo Cs,such as high power consumption and large area overhead.Therefore,No C became a major research hotspot.However,with the further study on No C,it gradually shows many shortcomings,such as large electromagnetic interference,high power loss,high crosstalk noise,large time delay and so on.Hence,the No C using metal interconnection has gradually failed to meet the needs of the rapid development of MPSo Cs.At this time,optical interconnection technology appeared in the public view.Compared with traditional electrical interconnection,optical interconnection has the advantages of lower loss,lower crosstalk,lower delay and higher bandwidth.With the continuous development of optical interconnection technology,optical networks-on-chips(ONo Cs)that uses optical connections instead of electrical connections has been proposed,which can effectively overcome the problems faced by No C.In recent years,as a new type of on-chip multiprocessor interconnection technology,ONo Cs is considered to have great development prospects,so it has been favored by researchers and developed rapidly.ONo Cs is a network that integrates lasers,optical modulators,optical routers and photodetectors on silicon on insulator(SOI)chips.However,due to the errors in the manufacturing process of these silicon-based photonic devices and the physical characteristics of the materials,when the multiple signals are transmitted in ONo Cs,power loss and crosstalk noise will inevitably be produced.Furthermore,the power loss and crosstalk noise will accumulate with the expansion of the network size of the ONo Cs.When it accumulates to a certain level,the optical signal will be distorted,resulting in a decline in communication quality.In severe cases,it will even affect the communication performance of the whole ONo Cs and limit the expansion of network scale.By developing optical devices based on new materials and designing novel optical routers and ONo Cs structures,the power loss and crosstalk noise can be reduced.In addition,after the types of silicon-based devices and the structures of optical routers and ONo Cs are determined,the communication quality can also be effectively improved by using routing optimization algorithms to choose routing paths with low power consumption and crosstalk.And with the expansion of network scale,the optimization algorithm will perform better in improving network performance.Therefore,in this paper,we focus on power loss and crosstalk noise,and propose an algorithm for routing paths selection in 2D-Mesh ONo Cs.Taking the dimension-order routing algorithm as a reference,the physical characteristics of ONo Cs are analyzed when two routing algorithms are used in different network scales.The main research contents of this paper are as follows:1.The components of the optical transmission unit,namely the silicon-based optical waveguide,the microring resonator and basic optical switching elements(BOSEs)are theoretically analyzed,and the calculation models of power loss and crosstalk noise of BOSEs are established.2.Based on the analysis of optical transmission unit,the calculation model of power loss of optical router is established.In order to better model the ONo Cs,an approximate worst-case crosstalk noise model for five-port optical routers is proposed.3.Based on the analysis of the basic optical devices and the optical router,the calculation models of power loss,crosstalk noise,optical signal-to-noise ratio(OSNR)and bit brror rate(BER)of 2D-Mesh ONo Cs are established.4.Based on the calculation models of power loss and crosstalk noise,the structural characteristics of five-port optical router and 2D-Mesh ONo Cs,we propose a routing optimization algorithm for selecting routing paths with low loss and crosstalk,and the optimization algorithm is named as the minimum loss routing algorithm.5.The Cygnus optical router is used to construct 2D-Mesh ONo Cs,Gurobi and Python are used for co-simulation.The power loss,crosstalk,OSNR and BER in the optical routing paths selected by the minimum loss routing algorithm and the dimensionorder routing algorithm are analyzed.Meanwhile,the Optisystem is used to build a simulation platform to process the simulation data obtained by the two routing algorithms to obtain the input and output waveform diagram,eye diagram and maximum Q factor of the signals.The results show that when the network size of the 2D-Mesh ONo Cs is 5×5 and the input optical power is 1 m W,the average power loss of the optical routing paths selected by the minimum loss routing algorithm is 16.82% lower than that of the dimension-order routing paths.And when the network size of the ONo Cs is 6 × 6,the average power loss of the optical routing paths selected by the minimum loss routing algorithm is 21.19%lower than that of the dimension-order routing paths.In addition,it can be found by numerical simulation that the optical routing paths selected by the minimum loss routing algorithm show better performance than the dimension-order routing paths in crosstalk noise,OSNR,BER and so on.When the optical signal is transmitted from the processing core(1,1)to the processing core(P,P)P ? {5,6,7,8,9,10,11,12},the minimum loss routing algorithm can effectively reduce the power loss,crosstalk noise,BER and improve the OSNR of the optical signal compared with the dimension-order routing algorithm.Moreover,with the gradual expansion of the network scale,the gap between the two algorithms is more obvious.By using the Optisystem to build the simulation platform to obtain the output waveforms and eye diagrams of the same optical signal after passing through the longest optical links selected by different routing algorithms.The results show that when the network scale is large,the optical signal can still have a clear output waveform and eye diagram after passing through the longest optical link selected by the minimum loss routing algorithm.It can be seen that the routing algorithm proposed in this paper can adapt to the changes of network scale better than the dimension-order routing algorithm,which has important application value for large-scale ONo Cs in the future.