Split-Wedge Antennas with Sub-5 nm Gaps for Plasmonic Nanofocusing
Document Type
Article
Abstract
We present a novel plasmonic antenna structure, a split-wedge antenna, created by splitting an ultrasharp metallic wedge with a nanogap perpendicular to its apex. The nanogap can tightly confine gap plasmons and boost the local optical field intensity in and around these opposing metallic wedge tips. This three-dimensional split-wedge antenna integrates the key features of nanogaps and sharp tips, i.e., tight field confinement and three-dimensional nanofocusing, respectively, into a single platform. We fabricate split-wedge antennas with gaps that are as small as 1 nm in width at the wafer scale by combining silicon V-grooves with template stripping and atomic layer lithography. Computer simulations show that the field enhancement and confinement are stronger at the tip-gap interface compared to what standalone tips or nanogaps produce, with electric field amplitude enhancement factors exceeding 50 when near-infrared light is focused on the tip-gap geometry. The resulting nanometric hotspot volume is on the order of λ3/106. Experimentally, Raman enhancement factors exceeding 107 are observed from a 2 nm gap split-wedge antenna, demonstrating its potential for sensing and spectroscopy applications.
Department(s)
Physics and Engineering
Publication Title
Nano Letters
Volume
16
Issue
12
First Page
7849
Last Page
7856
Publication Date
12-14-2016
DOI
10.1021/acs.nanolett.6b04113
ISSN
15306984
E-ISSN
15306992
Recommended Citation
Chen, Xiaoshu; Lindquist, Nathan C.; Klemme, Daniel J.; Nagpal, Prashant; Norris, David J.; and Oh, Sang Hyun, "Split-Wedge Antennas with Sub-5 nm Gaps for Plasmonic Nanofocusing" (2016). Physics and Engineering Faculty Publications. 15.
https://spark.bethel.edu/physics-faculty/15