Extended Worst-Case OSNR Searching Algorithm for Optical Network-on-Chip Using a Semi-Greedy Heuristic with Adaptive Scan Range

Abstract

The advances in silicon photonics technology have facilitated the realization of optical network-on-chips (ONoCs) to cope with the physical limitations of metal interconnections in traditional CMOS integrated circuits. As the performance and reliability of optical links are adversely affected by insertion losses and crosstalk, which inevitably occur during the propagation of optical signals, optimizing the power of a laser source requires a sophisticated analysis of the optical signal-to-noise ratio (OSNR). Calculating the worst-case OSNR for all possible communication links in an ONoC is an NP-hard problem even under the assumption of a single-wavelength laser source. Moreover, when expanding the design space by accommodating wavelength-division multiplexing (WDM), semiconductor optical amplifier (SOA), diverse topologies, and the associated router architectures, the computational complexity becomes excessive. Therefore, in this study, we propose an extended worst-case OSNR search algorithm (EWOSA) that significantly reduces the computational burden through a preprocessing algorithm that reduces the number of candidate paths when the combined effect of the insertion loss and crosstalk on the OSNR is considered. Simulation results demonstrate that the EWOSA can identify approximately 0.18 dB lower worst-case OSNR than the existing formal worst-case analysis method in 8\times 8 mesh-based ONoC, and this improvement in OSNR accuracy becomes more apparent (up to 4.81 dB) when SOAs are deployed in ONoCs. Furthermore, the EWOSA can be used for OSNR optimization, owing to its rapid analysis speed and generality.