Nanoscale-Confined Terahertz Polaritons in a van der Waals Crystal.
Adv Mater
; 33(2): e2005777, 2021 Jan.
Article
em En
| MEDLINE
| ID: mdl-33270287
ABSTRACT
Electromagnetic field confinement is crucial for nanophotonic technologies, since it allows for enhancing light-matter interactions, thus enabling light manipulation in deep sub-wavelength scales. In the terahertz (THz) spectral range, radiation confinement is conventionally achieved with specially designed metallic structures-such as antennas or nanoslits-with large footprints due to the rather long wavelengths of THz radiation. In this context, phonon polaritons-light coupled to lattice vibrations-in van der Waals (vdW) crystals have emerged as a promising solution for controlling light beyond the diffraction limit, as they feature extreme field confinements and low optical losses. However, experimental demonstration of nanoscale-confined phonon polaritons at THz frequencies has so far remained elusive. Here, it is provided by employing scattering-type scanning near-field optical microscopy combined with a free-electron laser to reveal a range of low-loss polaritonic excitations at frequencies from 8 to 12 THz in the vdW semiconductor α-MoO3 . In this study, THz polaritons are visualized with i) in-plane hyperbolic dispersion, ii) extreme nanoscale field confinement (below λo /75), and iii) long polariton lifetimes, with a lower limit of >2 ps.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Adv Mater
Assunto da revista:
BIOFISICA
/
QUIMICA
Ano de publicação:
2021
Tipo de documento:
Article
País de afiliação:
Alemanha