Universal Method for Constructing Fault-Tolerant Optical Routers Using RRW

High-speed data transmission enabled by photonic network-on-chip (PNoC) has been regarded as a significant technology to overcome the power and bandwidth constraints of electrical network-on-Chip (ENoC). This has given rise to an exciting new research area, which has piqued the public's attention. Current on-chip architectures cannot guarantee the reliability of PNoC, due to component failures or breakdowns occurring, mainly, in active components such as optical routers (ORs). When such faults manifest, the optical router will not function properly, and the whole network will ultimately collapse. Moreover, essential phenomena such as insertion loss, crosstalk noise, and optical signal-to-noise ratio (OSNR) must be considered to provide fault-tolerant PNoC architectures with low-power consumption. The main purpose of this manuscript is to improve the reliability of PNoCs without exposing the network to further blocking or contention by taking the effect of backup paths on signals sent over the default paths into consideration. Thus, we propose a universal method that can be applied to any optical router in order to increase the reliability by using a reliable ring waveguide (RRW) to provide backup paths for each transmitted signal within the same router, without the need to change the route of the signal within the network. Moreover, we proposed a simultaneous transmission probability analysis for optical routers to show the feasibility of this proposed method. This probability analyzes all the possible signals that can be transmitted at the same time within the default and the backup paths of the router. Our research work shows that the simultaneous transmission probability is improved by 10% to 46% compared to other fault-tolerant optical routers. Furthermore, the worst-case insertion loss of our scheme can be reduced by 46.34% compared to others. The worst-case crosstalk noise is also reduced by 24.55%, at least, for the default path and 15.7%, at least, for the backup path. Finally, in the network level, the OSNR is increased by an average of 68.5% for the default path and an average of 15.9% for the backup path, for different sizes of the network.