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Nanoholes arrays as effective SERS substrates with multiple wavelength SERS response and large electromagnetic SERS enhancement factors
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Paper Abstract

Bridged-bowtie nanohole arrays and cross bridged-bowtie nanohole arrays in a gold film are presented as surfaceenhanced Raman scattering (SERS) substrates. We employed the numerical FDTD method to calculate the maximum electromagnetic SERS enhancement factor (EF) as a function of wavelength. It is found that the proposed nanohole arrays do not only display an extremely large enhancement factor but also have the hotspot spread over a larger area compared to the various other nanopillar structures. The calculation of electromagnetic SERS enhancement factor reveals that the cross bridged-bowtie nanohole arrays exhibit the maximum electromagnetic SERS EF of ~ 109 spreading over an area of 100 nm2. In addition, the electromagnetic SERS EF of ~ 108 is spread over 500 nm2 area which is higher than hotspot area in case of nanopillar structures. The resonance wavelength of the nanohole array can be tuned by varying the size of the nanoholes. These nanohole arrays can be employed both in transmission as well as in reflection mode as effective SERS substrates. In addition, bridged-bowtie and cross bridged-bowtie nanohole arrays show the significantly high electromagnetic SERS EF at more than one wavelength and therefore are useful for application involving multiple wavelength SERS response. Furthermore, the cross bridged-bowtie nanohole array exhibit the spatial tunability of hotspot by rotating the direction of polarization of incident field.

Paper Details

Date Published: 7 March 2019
PDF: 8 pages
Proc. SPIE 10894, Plasmonics in Biology and Medicine XVI, 1089418 (7 March 2019); doi: 10.1117/12.2510828
Show Author Affiliations
Nitin Gupta, Indian Institute of Technology Delhi (India)
Rajib R. Ghosh, Indian Institute of Technology Delhi (India)
Anuj Dhawan, Indian Institute of Technology Delhi (India)

Published in SPIE Proceedings Vol. 10894:
Plasmonics in Biology and Medicine XVI
Tuan Vo-Dinh; Ho-Pui A. Ho; Krishanu Ray, Editor(s)

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