1 research outputs found
Terahertz Nanoimaging of Graphene
Accessing the nonradiative near-field
electromagnetic interactions with high in-plane momentum (<i>q</i>) is the key to achieve super resolution imaging far beyond
the diffraction limit. At far-infrared and terahertz (THz) wavelengths
(e.g., 300 μm = 1 terahertz = 4 meV), the study of high <i>q</i> response and nanoscale near-field imaging is still a nascent
research field. In this work, we report on THz nanoimaging of exfoliated
single and multilayer graphene flakes by using a state-of-the-art
scattering-type near-field optical microscope (s-SNOM). We experimentally
demonstrated that the single layer graphene is close to a perfect
near-field reflector at ambient environment, comparable to that of
the noble metal films at the same frequency range. Further modeling
and analysis considering the nonlocal graphene conductivity indicate
that the high near-field reflectivity of graphene is a rather universal
behavior: graphene operates as a perfect high-<i>q</i> reflector
at room temperature. Our work uncovers the unique high-<i>q</i> THz response of graphene, which is essential for future applications
of graphene in nano-optics or tip-enhanced technologies