2023/10/27 by Sukanta Nandi, Shany Z. Cohen, Danveer Singh +4 · 1 voice
Materials Science · Physics and Astronomy · #2D Materials and Applications #Graphene research and applications #Topological Materials and Phenomena
paper · doi:10.1021/acs.nanolett.3c03128
openalex publication_date 2023/10/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/18
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 Bi 2 Se 3 nanobeams (NBs). We extract the MIR optical constants of Bi 2 Se 3, 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 Bi 2 Se 3 for quantum circuitry, nonlinear generation, high-Q metaphotonics, and photodetection.