Directed xor/xnor Logic Gates Using U-to-U Waveguides and Two Microring Resonators

We propose and demonstrate a directed optical logic circuit, which can perform the XOR and XNOR logical operations based on U-to-U waveguides and two microring resonators. Compared to the previous structure, no waveguide crossings exist in the proposed circuit, which is beneficial to reduce the insertion loss and crosstalk of the device. Two electrical signals representing the two operands of the logical operation are employed to modulate two microring resonators through the thermo-optic effect, respectively. The operation result is represented by the output optical signal. For proof of principle, XOR and XNOR operations at 10 kb/s are demonstrated.