Narrow and deep fano resonances in a rod and concentric square ring-disk nanostructures.
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.
State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062, China. tqjia@phy.ecnu.edu.cn.
Yanyan
Y
Huo
Tianqing
T
Jia
Yi
Y
Zhang
Hua
H
Zhao
Shian
S
Zhang
Donghai
D
Feng
Zhenrong
Z
Sun
D003198:Computer Simulation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D008962:Models, Theoretical; D012542:Scattering, Radiation; D020349:Surface Plasmon Resonance / Q000295:instrumentation* / Q000379:methods*; D014159:Transducers