Far-field excitation of single graphene plasmon cavities with ultracompressed mode volumes
Epstein, Itai, Alcaraz, David, Huang, Zhiqin, Pusapati, Varun-Varma, Hugonin, Jean-Paul, Kumar, Avinash, Deputy, Xander, Khodkov, Tymofiy, Rappoport, Tatiana G., Hong, Jin Yong, Peres, N. M. R., Kong, Jing, Smith, David R., Koppens, Frank H. L.
Abstract
Acoustic graphene plasmons are highly confined electromagnetic modes carrying large momentum and low loss in the mid-infrared and terahertz spectra. However, until now they have been restricted to micrometer-scale areas, reducing their confinement potential by several orders of magnitude. Using a graphene-based magnetic resonator, we realized single, nanometer-scale acoustic graphene plasmon cavities, reaching mode volume confinement factors of ~5 × 1010 Such a cavity acts as a mid-infrared nanoantenna, which is efficiently excited from the far field and is electrically tunable over an extremely large broadband spectrum. Our approach provides a platform for studying ultrastrong-coupling phenomena, such as chemical manipulation via vibrational strong coupling, as well as a path to efficient detectors and sensors operating in this long-wavelength spectral range.