English

Near-field refractometry of van der Waals crystals

Mesoscale and Nanoscale Physics 2025-07-21 v3 Optics

Abstract

Common techniques for measuring refractive indices, such as ellipsometry and goniometry, are ineffective for van der Waals crystal flakes because of their high anisotropy and small, micron-scale, lateral size. To address this, we employ near-field optical microscopy to analyze the guided optical modes within these crystals. By probing these modes in MoS2_2 flakes with subwavelength spatial resolution at a wavelength of 1570nm1570\,\mathrm{nm}, we determine both the in-plane and out-of-plane permittivity components of MoS2_2 as 16.1116.11 and 6.256.25, respectively, with a relative uncertainty below 1%1\%, while overcoming the limitations of traditional methods.

Keywords

Cite

@article{arxiv.2411.07926,
  title  = {Near-field refractometry of van der Waals crystals},
  author = {Martin Nørgaard and Torgom Yezekyan and Stefan Rolfs and Christian Frydendahl and N. Asger Mortensen and Vladimir A. Zenin},
  journal= {arXiv preprint arXiv:2411.07926},
  year   = {2025}
}