Electro-Optic Ripple-Carry Adder in Integrated Silicon Photonics for Optical Computing

Photonic integrated circuits with compact size and low power consumption have opened the possibility of realization of ultrahigh-speed and energy-efficient optical computing in an integrated system that may be comparable to CMOS-based electrical integrated circuits in many aspects. Directed logic is an innovative paradigm that can make full use of the advantages of electronics and photonics for optical computing. In this paper, we propose various designs of directed-logic-based electro-optic ripple-carry adders in integrated silicon photonics, which replace the electrical components in the critical path using optical counterparts. All control signals are applied simultaneously through ultralow-power microdisk modulators so that the propagation delay could be reduced significantly. A two-bit thermal-optic full adder based on microdisk modulators is demonstrated as a proof of concept along with a projection of high-speed performance. The proposed electro-optic full adder paves the way to future low-power-consumption and large-bandwidth optical computing in integrated silicon photonics.