In nature, magnetic effects on materials are weaker than their electric counterparts. Magnetic polarizability is especially difficult to achieve at optical frequencies since natural materials are non-magnetic at this frequency range and magnetic effects can thus only be generated by carefully tailoring the spatial distribution of electric permittivity. Plasmonic nanostructures offer a flexible platform to engineer meta-atoms that satisfy such conditions and enhance the local magnetic field. However, thus far, this magnetic enhancement has always been accompanied with an enhancement of the electric response as well, such that pure magnetic modes were not yet observed in plasmonic systems. In this work, we design, fabricate and characterize a novel plasmonic nanostructure, which supports a pure magnetic dipole mode under plane wave excitation without contamination from electric modes. This study employs rigorous multipolar mode analysis and clearly distinguishes magnetic dipole and electric quadrupole effects. The link between structural asymmetry and multipole composition that is revealed in this work will be particularly useful in research on symmetry-sensitive physical phenomena, including optically induced atomic transition, optical forces, fluorescence, thermal emission and nonlinear optics.
Olivier J. F. Martin, "Observation of pure magnetism at optical frequencies in a plasmonic system (Conference Presentation)," Proc. SPIE 10722, Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XVI, 107220Q (Presented at SPIE Nanoscience + Engineering: August 21, 2018; Published: 17 September 2018); https://doi.org/10.1117/12.2321160.5836035315001.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the proceedings. They include the speaker's narration with video of the slides and animations. Most include full-text papers. Interactive, searchable transcripts and closed captioning are now available for most presentations.
Search our growing collection of more than 22,000 conference presentations, including many plenaries and keynotes.