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Highly Confined Tunable Mid-Infrared Plasmonics in Graphene Nanoresonators
journal contribution
posted on 2013-06-12, 00:00 authored by Victor
W. Brar, Min Seok Jang, Michelle Sherrott, Josue J. Lopez, Harry A. AtwaterSingle-layer graphene has been shown
to have intriguing prospects
as a plasmonic material, as modes having plasmon wavelengths ∼20
times smaller than free space (λp ∼ λ0/20) have been observed in the 2–6 THz range, and active
graphene plasmonic devices operating in that regime have been explored.
However there is great interest in understanding the properties of
graphene plasmons across the infrared spectrum, especially at energies
exceeding the graphene optical phonon energy. We use infrared microscopy
to observe the modes of tunable plasmonic graphene nanoresonator arrays
as small as 15 nm. We map the wavevector-dependent dispersion relations
for graphene plasmons at mid-infrared energies from measurements of
resonant frequency changes with nanoresonator width. By tuning resonator
width and charge density, we probe graphene plasmons with λp ≤ λ0/100 and plasmon resonances as
high as 310 meV (2500 cm–1) for 15 nm nanoresonators.
Electromagnetic calculations suggest that the confined plasmonic modes
have a local density of optical states more than 106 larger
than free space and thus could strongly increase light–matter
interactions at infrared energies.