Crosstalk Penalty in Microring-Based Silicon Photonic Interconnect Systems

Abstract

We examine inter-channel and intra-channel crosstalk power penalties between non-return-to-zero on-off keying (NRZ-OOK) wavelength-division-multiplexing (WDM) channels for microring-based silicon photonic interconnects. We first propose a new model that relates the crosstalk power penalty to the interfering signals power, the extinction ratio of the non-return-to-zero, OOK modulated “victim” channel, and finally the bit-error-ratio that the power penalty is referenced to. As for inter-channel crosstalk, the proposed model agrees well with our recent experimental measurements. We leverage this model to quantify crosstalk induced power penalties in a microring based WDM receiver. We also propose an optimization procedure to equilibrate the power penalty across channels. We then compare our model with intra-channel crosstalk measurements, where two NRZ channels are at the same wavelength and are simultaneously routed to different paths by two cascaded ring resonators. We remark that intra-channel crosstalk is very sensitive to the data rate of NRZ channels. As data rate increases, the observed disturbances exceed what models predict. Based on these observations, we propose an empirical modification of the original model for estimating intra-channel crosstalk power penalties in high ( $>$ 20 Gb/s) data rate situations.