A Three-Dimensional Plasmonic Nanostructure with Extraordinary Optical Transmission
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We report a 3D plasmonic nanostructure having an extraordinary optical transmission due to localized surface plasmon (LSP) coupling between nanoholes and nanodisks. The nanostructure contains a free-standing gold nanohole array (NHA) film above a cavity and an array of nanodisks at the bottom of the cavity that is aligned with the NHA. For the device, the LSP-mediated resonance position was dependent on the hole and nanodisk diameter as well as the separation distance. Also, the effect of LSP coupling between each hole and corresponding nanodisk became negligible for cavities deeper than 200 nm as observed as a disappearance of the LSP resonance. The greatest LSP resonance transmission and the highest electric field intensity were observed for the structure with the shallowest cavity. In addition, the structure had high surface plasmon resonance sensitivity and may have potential for surface-enhanced Raman spectroscopy and optical trapping applications.
KeywordsSurface plasmon Plasmonics Nanostructure fabrication Nanohole array
The authors thank Dr. Todd Simpson for his technical support at the Nanofab Laboratory at University of Western Ontario (UWO). This project was funded by grants from the Natural Sciences and Engineering Research Council of Canada (NSERC) to Dr. Bozena Kaminska and Dr. Jeffrey J.L. Carson. Dr. Fartash Vasefi was supported by a London Regional Cancer Program Translational Breast Cancer Research Trainee Fellowship.
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