Research On Low-Power Optical Network-on-Chip

With the growing amount of cores of system-on-chip,the bandwidth requirement of intercore communication is becoming larger and larger.Hence,a more efficient interconnect network is needed to support the inter-core communication.Compared with traditional interconnect method,optical interconnect can achieve higher order of magnitude communication bandwidth,and its link power consumption scarcely increase with data transmission rate.Therefore,optical interconnect becomes one of the most promising interconnect technologies for on-chip communication systems.However,driving silicon photonic links need laser sources to continuously inject light waves into the waveguides.The injected optical power cannot be effectively utilized for data communications in traditional optical power supply system,which will lead to a large amount of optical power being wasted.This thesis summarizes research background and status of optical power supply systems.An optical energy consumption model of optical network-on-chip is given,and two low-power optical power supply systems are proposed from the viewpoints of global communication prediction and group-based optical power supply.The following achievements are made:1.Statically providing laser power is quite power-consuming,and the power is usually not fully utilized.We proposed a dynamic laser power management scheme based on singlewrite-multi-read crossbar architecture.By keeping monitoring the overall communication requirement of the network,we build prediction model to forecast the overall network traffic within a future time slot,and further dynamically increase or decrease the output laser power up or down to a proper level.In this way,under the condition of guaranteeing the communication requirement of the network,the waste of laser power can be reduced as much as possible.The simulation results show that for different traffic modes,this laser power management scheme can significantly reduce the laser output power under low traffic load.2.The traffic distributions of many-core processors are usually not uniform.However,nodes with different communication requirements all get the same transmission abilities under traditional laser power supply scheme.This kind of unreasonable allotment of bandwidth resource leads to waste of laser power.Aiming at this problem,based on single-write-multi-read crossbar and improved low-power multi-write-single-read crossbar,we propose optical power delivery architectures which can be configured to be different grouping modes and nodes in each group are respectively supplied with power according to their communication requirements.Moreover,we design optical power allocation architectures based on on-chip laser sources,which make the nodes in different groups get wavelengths they really need.Hence,the allocation of bandwidth resource is balanced.The simulation analysis indicates that this laser power supply scheme can effectively reduce the overall laser power is reduced under specific conditions.