Spin-resolved near-field scanning optical microscopy for mapping of the spin angular momentum distribution of focused beams
We proposed and built a near-field scanning optical microscope (NSOM) to enable the characterization of the spin angular momentum (SAM) distribution of electromagnetic fields with nanoscale resolution. The NSOM probe was composed of a circular nanohole formed in a thick gold film that was deposited...
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Veröffentlicht in: | Applied physics letters 2020-06, Vol.116 (24) |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | We proposed and built a near-field scanning optical microscope (NSOM) to enable the characterization of the spin angular momentum (SAM) distribution of electromagnetic fields with nanoscale resolution. The NSOM probe was composed of a circular nanohole formed in a thick gold film that was deposited on a tapered cone fiber. The near-field signal, when coupled through the nanohole to the fiber, was split and analyzed using a combination of a quarter-wave plate and a polarizer to extract the two circular polarization components of the signal. This allowed us to characterize the out-of-plane SAM component, which was determined using the relationship Sz ∝ IRCP − ILCP. Using the developed system, we mapped the SAM distributions of a variety of tightly focused cylindrical vector vortex beams and thus validated the system's effectiveness. The proposed spin-resolved NSOM could be a valuable tool for studies of both near-field spin optics and topological photonics. |
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ISSN: | 0003-6951 1077-3118 |
DOI: | 10.1063/5.0004750 |