Multi-Stage 8 × 8 Silicon Photonic Switch Based on Dual-Microring Switching Elements

We demonstrate the first multi-stage 8 × 8 silicon photonic switch with switching elements based on dual add-drop microrings with a compact footprint of 4 mm
²
. This device leverages co-design of the switch architecture and the switching elements with a well-balanced set of performance metrics. The switching elements are designed to have a 3-dB optical passband of 165 GHz, exhibiting off- and on-resonance losses of 0.67 dB and 2 dB, respectively. Full characterization of all switch paths shows an end-to-end on-chip loss between 4.4 and 9.6 dB, with worst-case crosstalk leakage averaged at -16 dB. Owing to the efficient doped waveguide thermo-optic phase shifters, the device features a tuning efficiency of 48.85 GHz/mW. The reconfiguration time of the switch fabric is measured to be 1.2 μs and 0.5 μs at the rise and fall edge, respectively. The dual-microring switching element together with the multi-stage architecture preserves an end-to-end passband over 55 GHz. We validate the switch performance with optical paths of varying numbers of on- and off-resonance switching elements - less than 2 dB power penalties are obtained for all data routings at 32 Gbps.