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arXiv · 2411.07926

Near-field refractometry of van der Waals crystals

Martin Nørgaard·Torgom Yezekyan·Stefan Rolfs·Christian Frydendahl·N. Asger Mortensen·Vladimir A. Zenin
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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 MoS$_2$ flakes with subwavelength spatial resolution at a wavelength of $1570\,\mathrm{nm}$, we determine both the in-plane and out-of-plane permittivity components of MoS$_2$ as $16.11$ and $6.25$, respectively, with a relative uncertainty below $1\%$, while overcoming the limitations of traditional methods.

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Martin Nørgaard, Torgom Yezekyan, Stefan Rolfs, Christian Frydendahl, N. Asger Mortensen, Vladimir A. Zenin. 2024-11-12. Near-field refractometry of van der Waals crystals. https://doi.org/10.1515/nanoph-2025-0117

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