Non-blocking 2×2 switching unit based on nested silicon microring resonators with high extinction ratios and low crosstalks

In this paper, we propose and demonstrate a 2 × 2 optical Benes switching unit based on two nested silicon microring resonators （MRRs） monolithically integrated on a silicononinsulator （SOI） wafer. High extinction ratios （ERs） of about 44.7/38.0 dB and low crosstalk values of about -37.5/-45.2 dB at cross/bar states are obtained with the fabricated device. The operation principle is theoretically studied and the switching function is verified by system demonstration experiments with 10 and 12.5 Gb/s nonreturntozero （NRZ） signals. The switching speed on the order of gigahertz based on free carrier effect in silicon is also experimentally demonstrated.