Fourier analysis of near-field patterns generated by propagating polaritons
arXiv:2402.17225 · doi:10.1103/PhysRevApplied.22.014076
Abstract
Scattering-type scanning near-field optical microscope (s-SNOM) has become an essential tool to study polaritons - quasiparticles of light coupled to collective charge oscillations - via direct probing of their near field with a spatial resolution far beyond the diffraction limit. However, extraction of the polariton complex propagation constant from the near-field images requires subtle considerations that have not received necessary attention so far. In this study, we discuss important yet overlooked aspects of the near-field analysis. First, we experimentally demonstrate that the sample orientation inside the s-SNOM may significantly affect the near-field interference pattern of mid-infrared polaritons, leading to an error in momentum measurement up to 7.7% even for the modes with effective index of 12.5. Second, we establish a methodology to correctly extract the polariton damping rate from the interference fringes depending on their origin - the s-SNOM nano-tip or the material edge. Overall, our work provides a unified framework for the accurate extraction of the polariton momentum and damping from the near-field interference fringes.
15 pages, 4 figures
References in corpus (8)
- Infrared hyperbolic metasurface based on nanostructured van der Waals materials
- Subdiffractional focusing and guiding of polaritonic rays in a natural hyperbolic material
- Imaging exciton-polariton transport in MoSe2 waveguides
- Broad Spectral Tuning of Ultra-Low Loss Polaritons in a van der Waals Crystal by Intercalation
- Electrostatic Steering of Thermal Emission with Active Metasurface Control of Delocalized Modes
- Near-field probing of image phonon-polaritons in hexagonal boron nitride on gold crystals
- Quantitative near-field characterization of surface plasmon polaritons on monocrystalline gold platelets
- The Effect of Dust and Hotspots on the Thermal Stability of Laser Sails