Abstract

Sharp geometrical features in crescent-shaped plasmonic nanostructures facilitate electromagnetic hot spots that can be harnessed for sensitive detection of molecules and nanomaterials. For a given geometry of nanocrescent cylinder, the near-field optical resonance and enhancement are constants. It is desirable to tune this resonance and enhancement without altering the geometry of the nanocrescent cylinder. Herein, we numerically show how the near-field resonance and enhancement at the tip of a nanocrescent cylinder can be proximally tuned by incorporating a plasmonic nanostrip in the vicinity. Geometrical parameters, such as the nanocrescent cylinder–nanostrip distance ($\mathbf{g}$) and length ($\mathbf{l}$) of the nanostrip, were varied to tune the near-field optical properties. Our analysis revealed (i) an increment in near-field enhancement at the tip of the nanocrescent cylinder in the presence of a plasmonic nanostrip; (ii) a redshift in the dipolar plasmon mode accompanied by an increase in the near-field enhancement by decreasing $\mathbf{g}$ and increasing $\mathbf{l}$, independently; and (iii) variation in the near-field enhancement of plasmonic modes as a function of the excitation angle. Such tunable plasmonic configurations offer capabilities to design wavelength-tuned optical devices without altering the base geometry.

©2012 Optical Society of America

Dipole, quadrupole and octupole plasmon resonance modes in non-concentric nanocrescent/nanodisk structure: local field enhancement in the visible and near infrared regions

Y. Zhang, T.Q. Jia, S.A. Zhang, D.H. Feng, and Z. Z. Xu
Opt. Express 20(3) 2924-2931 (2012)

Nanostructures for surface plasmons

Junxi Zhang and Lide Zhang
Adv. Opt. Photon. 4(2) 157-321 (2012)

Palladium bridged gold nanocylinder dimer: plasmonic properties and hydrogen sensitivity

Arindam Dasgupta and G. V. Pavan Kumar
Appl. Opt. 51(11) 1688-1693 (2012)

Fano resonance properties of gold nanocrescent arrays

Zhongwei Liao, Bingpu Zhou, Yingzhou Huang, Shunbo Li, Shuxia Wang, and Weijia Wen
Appl. Opt. 53(28) 6431-6434 (2014)

Enhanced optical transmission through asymmetric nanostructured gold films

Lina Shi, Hailiang Li, Yuchan Du, and Changqing Xie
J. Opt. Soc. Am. B 29(12) 3377-3385 (2012)