Graphene-based linearly-tapered-slit hybrid plasmonic antenna for dynamic control of extraordinary optical transmission

This study provides insights into the theoretical exploration of dynamically enhanced extraordinary optical transmission (EOT) achieved through a hybrid plasmonic antenna under femtosecond laser excitation. The hybrid graphene-based linearly-tapered-slit (h-GBLTS) structures are milled into a gold-coated silica substrate, enabling active control of efficient light transmission in the visible regime. The investigation employs a time-dependent wave-propagating equation coupled with the Drude-Lorentz complex permittivity model to offer a comprehensive understanding of the ultrafast dynamics of EOT in spatial-temporal and spectrum regimes. The numerical solutions of this coupled model reveal the full spatiotemporal evolutions of EOT through the h-GBLTS plasmonic antenna at the nanoscale. It is proposed that a substantial increase of ∼5.4 times at 1.3 eV in the electric field of EOT is observed with thinner graphene layers when the graphene Fermi energy level is increased from ∼0.7 eV to ∼1.5 eV in a non-saturation region. Moreover, the linearly-tapered-slit structure induces spectral blue-shifts in resonance modes, enabling the incident infrared laser to shift to the visible regime in EOT. This result is explained by multipole oscillations at the plasmon resonance state, supporting plasmon hybridization and photon energy conversion to higher states. These findings show that graphene-integrated nanostructures could be key to shaping next-generation technologies. By integrating graphene into plasmonic systems, promising applications can be developed in high-efficiency photodetectors, infrared sensors, advanced communication systems, tunable light filters, etc.