Quantitative Analytical Spheroid Model for Scattering-Type Scanning Near-Field Optical Spectroscopy of Layered Samples
Abstract
Scattering-type scanning near-field optical microscopy (s-SNOM) is a versatile tool for probing optical properties at deeply subwavelength scales. Its theoretical modeling, however, typically relies on computationally intensive numerical simulations or phenomenological analytical models, limiting quantitative spectral interpretation. In our previous work, we introduced an exact analytical solution for the quasi-electrostatic prolate spheroid model of s-SNOM for homogeneous bulk samples, combining the accuracy of numerical simulations with the efficiency of analytical approaches. Here, we generalize this framework to multilayer samples using two equivalent methods: a generalized image charge method and a Fourier integral method. The resulting exact spheroid model reproduces finite-element simulations within numerical precision while retaining the computational efficiency of an analytical model. We validate the model experimentally for poly (methyl methacrylate) layers of different thicknesses, showing that a single set of geometrical parameters simultaneously reproduces multiple demodulation harmonics and all measured thicknesses, unlike the finite dipole model. We further demonstrate its applicability to strongly resonant SiC layers on dielectric and photoexcited InAs substrates, where existing analytical approaches fail. The model provides an efficient quantitative framework for interpreting multilayer s-SNOM spectra and extracting local optical properties.
Related
- STEM-Bank-26: An Open Dataset of Analytical Scanning Transmission Electron Microscopy Images and Spectra
- Automated end-station at the soft X-ray beamline featuring robotic air-to-ultrahigh-vacuum sample transfer, scanning probe spectroscopy, and machine learning analysis
- WannierSTM: Efficient superconducting scanning-probe spectroscopy from maximally localized Wannier functions
- Intra-unit-cell Josephson scanning tunneling spectroscopy of the cuprate Bi1.2Pb0.8Sr2CaCu2O8+δ
- Analytical modeling of LRCS for multiple scattering of Lambertian dihedral angle
BibTeX
@misc{voronin2026quantitative,
title = {{Quantitative Analytical Spheroid Model for Scattering-Type Scanning Near-Field Optical Spectroscopy of Layered Samples}},
author = {Kirill V. Voronin and Edoardo Vicentini and Lars Mester and Rainer Hillenbrand and Alexey Y. Nikitin},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.01057},
eprint = {2611.01057},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.01057},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Quantitative Analytical Spheroid Model for Scattering-Type Scanning Near-Field Optical Spectroscopy of Layered Samples
AU - Kirill V. Voronin
AU - Edoardo Vicentini
AU - Lars Mester
AU - Rainer Hillenbrand
AU - Alexey Y. Nikitin
PY - 2026
DA - 2026/11/01
PB - arXiv
DO - 10.48550/arxiv.2611.01057
UR - https://arxiv.org/abs/2611.01057
AB - Scattering-type scanning near-field optical microscopy (s-SNOM) is a versatile tool for probing optical properties at deeply subwavelength scales. Its theoretical modeling, however, typically relies on computationally intensive numerical simulations or phenomenological analytical models, limiting quantitative spectral interpretation. In our previous work, we introduced an exact analytical solution for the quasi-electrostatic prolate spheroid model of s-SNOM for homogeneous bulk samples, combining the accuracy of numerical simulations with the efficiency of analytical approaches. Here, we generalize this framework to multilayer samples using two equivalent methods: a generalized image charge method and a Fourier integral method. The resulting exact spheroid model reproduces finite-element simulations within numerical precision while retaining the computational efficiency of an analytical model. We validate the model experimentally for poly (methyl methacrylate) layers of different thicknesses, showing that a single set of geometrical parameters simultaneously reproduces multiple demodulation harmonics and all measured thicknesses, unlike the finite dipole model. We further demonstrate its applicability to strongly resonant SiC layers on dielectric and photoexcited InAs substrates, where existing analytical approaches fail. The model provides an efficient quantitative framework for interpreting multilayer s-SNOM spectra and extracting local optical properties.
ER -