Mitigation of homodyne crosstalk noise in silicon photonic NoC architectures with tunable decoupling

Photonic network-on-chip (PNoC) architectures employ photonic waveguides with dense-wavelength-division-multiplexing (DWDM) for signal traversal and microring resonators (MRs) for signal modulation, to enable high bandwidth on-chip transfers. Unfortunately, due to the resonant nature of MRs, the power built-up in their cavity gradually recouples back into the photonic waveguides. This recoupled power induces time-dependent unfilterable homodyne crosstalk noise, when the wavelength of the recoupled power matches with the wavelength of a signal in the waveguide. The homodyne crosstalk in turn deteriorates the signal-to-noise ratio (SNR) and on-chip communication reliability. This paper presents a novel lightweight technique to mitigate homodyne crosstalk noise in DWDM-based PNoCs. We evaluate the effectiveness and overhead of our technique by implementing it for well-known PNoC architectures, including Corona, Firefly and Flexishare. Experimental results indicate that our approach when implemented on these PNoCs can improve the worst-case SNR by up to 37.6% compared to the baseline versions of these PNoCs, thereby significantly enhancing reliability, at the cost of up to 19.2% energy overhead and 1.7% photonic area overhead.