Probing Inherent Optical Anisotropy in Substrates via Direct Nanoimaging of Mie Scattering

In this study, we investigated the optical properties of a transition metal dichalcogenide (TMD) substrate via Mie-scattering-induced surface analysis (MISA). Employing near-field optical microscopy and finite-difference time-domain (FDTD) simulations, we systemically prove and directly visualize the Mie scattering of superspherical gold nanoparticles (s-AuNPs) at the nanoscale. Molybdenum disulfide substrates exhibited optical isotropy, while rhenium disulfide (ReS₂) substrates showed anisotropic behavior attributed to the interaction with incident light's electric field. Our study revealed substantial anisotropic trends in Mie scattering, particularly in the near-infrared energy range, with ReS₂ exhibiting more pronounced spectral and angular responses in satellite peaks. Our results emphasize the application of Mie scattering, exploring the optical properties of substrates and contributing to a deeper understanding of nanoscale light-matter interactions.