Research And Optimization On Reliability Of Optical Networks-on-Chip Based On Thermal Effect

In recent years,with the increasing demand for high-performance chips and the continuous development of nanotechnology and silicon-based photon technology,multi-core technology,as a technology that can solve the problems of power consumption limit and mutual delay in the design of single-core chips,emerges under the above background and demand.Nowadays,hundreds of millions transistors are integrated into a single chip to achieve more powerful functions.Therefore,the research on multiprocessor systems-on-chips(MPSoCs)has become a new trend.And how to choose an effective interconnection between processing cores to make full use of computing resources is an important factor to determine the performance of MPSoCs.The network on chip(NoC)is a new way to solve the interconnection problem of MPSoC,which can solve a series of problems brought by traditional bus architecture.NoC is a technology that introduces computer network technology into chip design.With the improvement of circuit integration and working frequency,traditional NoC with electric connection can produce the parasitic effect,resulting in the problems of high loss and high delay,which seriously limits the sustainable development of MPSoCs.Optical networks-on-chip(ONoCs),which uses optical connection instead of electrical connection,is expected to break the obstacles encountered by electrical interconnection NoC.Therefore,ONoCs,which has the advantages of high bandwidth,low energy consumption and low delay,has become a promising interconnection method on chip.And the research on ONoCs has become a hot topic in related fields.The realization of ONoCs is to integrate common silicon-based devices such as photon lasers,optical modulators,optical routers and photodetectors on silicon on insulator(SOI)chips.Silicon-based micro-ring resonators(MRs)are widely used in many fields due to their small size,low power consumption,and compatibility with COMS,such as modulators,filters,and photodetectors.Therefore,MRs is the key device to realize the communication function of ONoCs.In general,MRs in ONoCs works by changing resonance(ON)and non resonance(OFF)states.Ideally,the ON and OFF state MRs should maximize the coupling and passing of signal power.However,due to the defects of the current manufacturing process,the use of photonic devices will inevitably introduce crosstalk noise and insertion loss.Especially,MRs has the inherent characteristics of thermal sensitivity.The change of temperature will affect its own characteristics.And the chip temperature is inevitably change in the working process.Previous research shows that the temperature of chip fluctuates in time and space,and under typical operating conditions,the steady-state temperature of the whole chip can change more than 30?.Such temperature change can cause the resonance wavelength of MRs to shift.When the resonance wavelength of MRs drifts,there will be mismatch between the resonance wavelength and the working wavelength with effective information,which can lead to additional crosstalk noise and loss.And the accumulation of loss and crosstalk noise in the ONoCs network can affect the normal transmission of optical signals in the network,thus greatly reducing the communication reliability of ONoCs.Therefore,aiming at the influence of thermal effect on the performance for ONoCs,this paper puts forward the theoretical models and system analysis method of optical signal power loss and crosstalk noise of caused by thermal effect,and proposes an optimization scheme for the reliability of ONoCs.The main research works are as follows:1.The theoretical knowledge of ONoCs is described,and the physical structure and working principle of SOI-based MRs are analyzed.2.Based on the basic theory of thermo optic effect,the principle and law for resonance wavelength shift of MRs with temperature change are analyzed.3.The correlation function is fitted according to the transmission spectrum of Mrs.Moreover,according to the resonance wavelength drift formula of MRs under the action of thermal effect,the relationship between the loss and crosstalk noise coefficient of MRs in different states changing with temperature are derived.4.The routing rules and switching mechanism used in ONoCs are analyzed.And a general model of five port optical router for ONoCs is proposed.5.The structure models of basic optical switching device level,router level and network level are constructed,and the theoretical analysis models of loss and crosstalk noise caused by thermal effect in device level,router level and transmission path in the network are established.Finally,the proposed model is evaluated by numerical simulation of mesh-based ONoCs using different routers.In the simulation process,we calculate different communication optical links in the ONoCs,and find the worst communication link to evaluate the performance of ONoCs caused by thermal effect.6.An all-optical encoder based on linear block code is designed,and a reliable communication system based on this encoder is proposed.All optical linear coding is used to solve the problem of reliability reduction of ONoCs caused by thermal effect.The simulation results show that the reliable communication scheme can effectively optimize the quality of information transmission and improve the reliability of communication.The above work shows that the thermal effect has a great influence on the performance of ONoCs.No matter which kind of optical router is used,the performance of ONoCs declines obviously with the temperature floating on the chip.With the increase of temperature,the OSNR and BER decrease greatly.And with the increase of network scale,the above phenomenon becomes more and more obvious,which greatly reduces the reliability of ONoCs.The reliable communication system based on linear block code proposed in this paper can effectively improve the OSNR and reduce the BER,so it has significant effect on improving the reliability of the communication system.