Extracting the infrared permittivity of sio2 substrates locally by near-field imaging of phonon polaritons in a van der waals crystal

Patricia Aguilar-Merino, Gonzalo Álvarez-Pérez, Javier Taboada-Gutiérrez, Jiahua Duan, Iván Prieto, Luis Manuel Álvarez-Prado, Alexey Y. Nikitin, Javier Martín-Sánchez*, Pablo Alonso-González*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Layered materials in which individual atomic layers are bonded by weak van der Waals forces (vdW materials) constitute one of the most prominent platforms for materials research. Particularly, polar vdW crystals, such as hexagonal boron nitride (h-BN), alpha-molybdenum trioxide (α-MoO3) or alpha-vanadium pentoxide (α-V2O5), have received significant attention in nano-optics, since they support phonon polaritons (PhPs)—light coupled to lattice vibrations— with strong electromagnetic confinement and low optical losses. Recently, correlative far-and near-field studies of α-MoO3 have been demonstrated as an effective strategy to accurately extract the permittivity of this material. Here, we use this accurately characterized and low-loss polaritonic material to sense its local dielectric environment, namely silica (SiO2), one of the most widespread substrates in nanotechnology. By studying the propagation of PhPs on α-MoO3 flakes with different thicknesses laying on SiO2 substrates via near-field microscopy (s-SNOM), we extract locally the infrared permittivity of SiO2. Our work reveals PhPs nanoimaging as a versatile method for the quantitative characterization of the local optical properties of dielectric substrates, crucial for understanding and predicting the response of nanomaterials and for the future scalability of integrated nanophotonic devices.

Original languageEnglish
Article number120
Pages (from-to)1-11
Number of pages11
JournalNanomaterials
Volume11
Issue number1
DOIs
Publication statusPublished - Jan 2021
Externally publishedYes

Keywords

  • Infrared permittivity
  • Phonon polaritons
  • S-SNOM
  • Van der Waals materials

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