Narrow and Deep Fano Resonances in a Rod and Concentric Square Ring-Disk Nanostructures

Sensors

Yanyan Huo²  Tianqing Jia¹  Yi Zhang²  Hua Zhao²  Shian Zhang²  Donghai Feng² 

[1] State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062, China;

关键词: Fano resonance;    plasmonic nanostructures;    optical sensor;    Fano linewidth spectral contrast ratio;    figure of merit;   

DOI  :  10.3390/s130911350

来源: mdpi

【 摘 要 】

Localized surface plasmon resonances (LSPRs) in metallic nanostructures have been studied intensely in the last decade. Fano interference is an important way to decrease the resonance linewidth and enhance the spectral detection resolution, but realizing a Fano lineshape with both a narrow linewidth and high spectral contrast-ratio is still challenging. Here we propose a metallic nanostructure consisting of a concentric square ring-disk (CSRD) nanostructure and an outside nanorod. Fano linewidth and spectral contrast ratio can be actively manipulated by adjusting the gap between the nanorod and CSRD, and by adjusting the gap between the ring and disk in CSRD. When the gap size in CSRD is reduced to 5 nm, the quadrupolar Fano linewidth is of 0.025 eV, with a contrast ratio of 80%, and the figure of merit reaches 15.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.