Unveiling Local Optical Properties Using Nanoimaging Phase Mapping in High-Index Topological Insulator Bi2Se3 Resonant Nanostructures

Sukanta Nandi, Shany Z. Cohen, Danveer Singh, Michal Poplinger, Pilkhaz Nanikashvili, Doron Naveh, Tomer Lewi

Research output: Contribution to journalArticlepeer-review

Abstract

Topological insulators are materials characterized by an insulating bulk and high mobility topologically protected surface states, making them promising candidates for future optoelectronic and quantum devices. Although their electronic properties have been extensively studied, their mid-infrared (MIR) properties and prospective photonic capabilities have not been fully uncovered. Here, we use a combination of far-field and near-field nanoscale imaging and spectroscopy to study chemical vapor deposition-grown Bi2Se3 nanobeams (NBs). We extract the MIR optical constants of Bi2Se3, revealing refractive index values as high as n ∼ 6.4, and demonstrate that the NBs support Mie resonances across the MIR. Local near-field reflection phase mapping reveals domains of various phase shifts, providing information on the local optical properties of the NBs. We experimentally measure up to 2π phase-shift across the resonance, in excellent agreement with finite-difference time-domain simulations. This work highlights the potential of Bi2Se3 for quantum circuitry, nonlinear generation, high-Q metaphotonics, and photodetection.

Original languageEnglish
Pages (from-to)11501-11509
Number of pages9
JournalNano Letters
Volume23
Issue number24
DOIs
StatePublished - 27 Dec 2023

Keywords

  • Mie resonator
  • Topological insulator
  • bismuth selenide
  • mid-infrared
  • phase-mapping
  • s-SNOM

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Condensed Matter Physics
  • Mechanical Engineering
  • Bioengineering
  • General Materials Science

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