Ultrafast Active Control of All-Optical Plasmonic Logic Gates States

Surface Plasmon Polariton (SPP) can confine electromagnetic fields at metal-dielectric interfaces, breaking the diffraction limit and enabling sub-wavelength light confinement. Ultra-high modulation speeds of plasmonic logic gate devices can pave the way for high-speed information processing. However, the ultrafast manipulation of optical plasmonic logic gates on the femtosecond scale remains a challenge. In this paper, we propose a metal-insulator-metal (MIM) waveguide structure for plasmonic OR and XOR gates. By superimposing two circularly polarised light pulses with a 100 fs time delay, we achieve switching between three states of both the plasmonic OR and XOR gates. Specifically, the XOR gate realises switching by adjusting the relative phase delay between left- and right-circularly polarised beams, undergoing transitions from "10 − 1" to "11 − 0" and then to "01–1" within 236 fs; the OR gate, in contrast, achieves switching by tuning the time delay between two left-circularly polarised beams, undergoing transitions from"10 − 1" to "11 − 1" and then to "01–1" within 298 fs. This research could form the basis for developing next-generation, high-speed, highly integrated and low-power-consumption photonic devices.