Near-field spectroscopy of Dirac plasmons in Bi2Se3 ribbon arrays

Lucy L. Hale, Zhengtianye Wang, C. Thomas Harris, Igal Brener, Stephanie Law, Oleg Mitrofanov

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Plasmons supported in the massless electron surface states of topological insulators (TIs), known as Dirac plasmons, have great potential in next generation optoelectronics. However, their inherent confinement to the surface makes the investigation of Dirac plasmons challenging. Near-field techniques provide the ideal platform to directly probe Dirac plasmons due to the sensitivity to evanescent fields at the surface. Here, we demonstrate the use of aperture near-field spectroscopy for the investigation of localized terahertz (THz) Dirac plasmon resonances in Bi2Se3 ribbon arrays with widths ranging from 10 to 40 µm. Unlike scattering THz near-field techniques, the aperture method is most sensitive to plasmons with the relevant lower-momenta corresponding to plasmon wavelengths on the scale of ∼20 µm. The combination of THz time-domain spectroscopy and aperture near-field microscopy enables sampling of localized Dirac plasmons in the near-field zone in the 0.5-2.5 THz range. We map the plasmon dispersion, which reveals a coupled plasmon-phonon polariton interaction. The near-field spectra show a higher contrast of the upper polariton branch in comparison with far-field observations. The information revealed by aperture near-field spectroscopy could deepen our understanding of the behavior of Dirac plasmons, leading to the potential development of real-world TI devices.

Original languageEnglish (US)
Article number051304
JournalAPL Photonics
Issue number5
StatePublished - May 1 2023

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Computer Networks and Communications

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