Design of an on-chip optical full-adder for optical directed logic using microring resonators

Optical directed logic circuits aim to perform multifunction logic operations using the optical switch network, in which the digital electrical signals regarded as the logic operands are applied to the optical switch to control the propagation of light over time, and the logic operation results are obtained at the output ports of the optical switch network in the form of light. Full-adder is the primary elementary unit for the realization of optical directed logic which generates both sum and carry bits in optical domain, for three given digital electrical signals. In this letter, we propose an on-chip Microwave Photonic Full-Adder gate for directed logic operation using silicon micro-ring resonators (MRRs). The possibility of using Silicon-on-insulator (SOI) based MRR as thermo-optic switch is described through thermo-optic effect. Three electrical input signals (logic operands) are applied across the micro-heaters above MRRs to determine the switching states of MRRs, and the full-adder logic operation results are directed to the output ports in the form of light, respectively. For proof of concept, the scattering matrix method is employed to establish numerical model of the device. Simulation results confirming described method are presented in this paper.