Ultrafast All-Optical Flip-Flops, Simultaneous Comparator-Decoder and Reconfigurable Logic Unit With Silicon Microring Resonator Switches

We present designs of all-optical SR, clocked-SR, D and T flip-flops, simultaneous single-bit comparator-decoder and reconfigurable logic unit based on all-optical switching by two-photon absorption induced free-carrier injection in silicon 2 × 2 add-drop microring resonators. The proposed circuits have been theoretically analyzed using time-domain coupled-mode theory and all-optical switching has been optimized for ultrafast (~25 ps), low-power operation (~25 mW) and high modulation (> 85%), enabling logic operations at 40 Gb/s. The designs are attractive due to advantages of high Q-factor, tunability, compactness, cascadibility, scalability, reconfigurability, simplicity and minimal number of switches and inputs for realization of the desired logic.