All-Optical Single-Channel Plasmonic Logic Gates.

Optical computing, renowned for its light-speed processing and low power consumption, typically relies on the coherent control of two light sources. However, there are challenges in stabilizing and maintaining high optical spatiotemporal coherence, especially for large-scale computing systems. The coherence requires rigorous feedback circuits and numerous phase shifters, introducing system instability and complexity. Here we propose an innovative logic gate using a single light source, with frequency and polarization serving as two virtual inputs. Our design leverages frequency-polarization multiplexed metasurfaces to achieve all basic logic operations by selectively routing surface plasmon polaritons. This single-channel logic gate maintains inherent coherence between frequency and polarization, thereby considerably eliminating stringent light-source specifications and numerous rigid phase controls and resulting in higher stability. Our device showcases unique application potentials in on-chip readout of encryption information by using random sequences as a one-time pad, unlocking fresh prospects for information protection and optical computing with other simple light sources.