Ultra-Compact Voltage-Controlled Dielectric-Cladded Graphene Plasmonic Waveguide Based Optical Logic Gate

We presented a novel graphene-based optical logic gate capable of functioning as both OR and AND gate controlled by the voltage applied to the graphene sheet. The design was inspired by a simple Y-coupler structure and employs a dielectriccoated graphene design that supports highly confined fundamental plasmonic mode, allowing it to serve as a waveguide medium. This high effective index mode enabled us to subwavelength size design, resulting in an ultra-compact optical device operating in the mid-infrared (MIR) wavelength range. The device leverages the inherently lossy nature of graphene plasmonic modes to switch between the two logic gate functions. By exploiting the voltage-controlled tunability of graphene’s chemical potential, which modulates its absorption loss, the device operates in two distinct modes: at high loss, it behaves as an AND gate, while at low loss, it functions as an OR gate. A constant transmission threshold of $23 \%$ of input power distinguishes the output “ 0 “ state and “ 1 “ state. The proposed structure features a compact footprint of $6.08 \mu m^{2}$ and demonstrates an average extinction ratio of $\sim 2 \mathrm{~dB}$ across the $9.5-10.5 \mu \mathrm{~m}$ wavelength range. Due to its ultra-compact design and reconfigurable functionality, this device is highly suitable for integration into photonic integrated circuits (PICs), enabling multifunctional logic operations in a compact form factor.