This study investigates the tunable properties of graphene plasmons using infrared nano-imaging techniques. The researchers demonstrate that common graphene/SiO₂/Si back-gated structures support propagating surface plasmons with a wavelength of about 200 nm at infrared frequencies. They show that both the amplitude and wavelength of these plasmons can be altered by gate voltage. The team also explores plasmon losses using plasmon interferometry, revealing that the dissipation is linked to the exotic electrodynamics of graphene. The tunable graphene devices outperform conventional metal-based structures in standard plasmonic figures of merit. The study highlights the potential of graphene as a medium for active infrared plasmonics, with applications in modern information processing systems.This study investigates the tunable properties of graphene plasmons using infrared nano-imaging techniques. The researchers demonstrate that common graphene/SiO₂/Si back-gated structures support propagating surface plasmons with a wavelength of about 200 nm at infrared frequencies. They show that both the amplitude and wavelength of these plasmons can be altered by gate voltage. The team also explores plasmon losses using plasmon interferometry, revealing that the dissipation is linked to the exotic electrodynamics of graphene. The tunable graphene devices outperform conventional metal-based structures in standard plasmonic figures of merit. The study highlights the potential of graphene as a medium for active infrared plasmonics, with applications in modern information processing systems.