Magnetic Plasmonic Fano Resonance at Optical Frequency

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 11; no. 18; pp. 2177 - 2181
• Main Authors: Bao, Yanjun, Hu, Zhijian, Li, Ziwei, Zhu, Xing, Fang, Zheyu
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 13.05.2015; Wiley Subscription Services, Inc
• Subjects: Fano resonance; Gold; magnetic modes; Magnetic resonance; Nanostructure; nanostructures; Nanotechnology; Optical frequency; Orientation; Plasmonics; Plasmons; polarized light; Simulation; surface plasmons; surface plasmons; Fano resonance; polarized light; magnetic modes; plasmonics; nanostructures
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201402989

Plasmonic Fano resonances are typically understood and investigated assuming electrical mode hybridization. Here we demonstrate that a purely magnetic plasmon Fano resonance can be realized at optical frequency with Au split ring hexamer nanostructure excited by an azimuthally polarized incident light. Collective magnetic plasmon modes induced by the circular electric field within the hexamer and each of the split ring can be controlled and effectively hybridized by designing the size and orientation of each ring unit. With simulated results reproducing the experiment, our suggested configuration with narrow line‐shape magnetic Fano resonance has significant potential applications in low‐loss sensing and may serves as suitable elementary building blocks for optical metamaterials. Pure magnetic plasmonic Fano resonance with a narrow resonance line‐shape is realized at optical frequencies by designing an Au split‐ring hexamer. By controlling the orientation and size of the ring, bright and dark magnetic mode interference and Fano resonance are generated with a full‐width‐at‐half‐maximum of about 25 nm, showing potential for narrow line‐shape engineering and low‐loss magnetic plasmon resonance applications.