Abstract
Controllable strong interactions between a nanocavity and a single emitter is important to manipulating optical emission in a nanophotonic system but challenging to achieve. Herein a three-dimensional DNA origami, named as DNA rack (DR) is proposed and demonstrated to deterministically and precisely assemble single emitters within ultra-small plasmonic nanocavities formed by closely coupled gold nanorods (AuNRs). Uniquely, the DR is in a saddle shape, with two tubular grooves that geometrically allow a snug fit and linearly align two AuNRs with a bending angle < 10°. It also includes a spacer at the saddle point to maintain the gap between AuNRs as small as 2–3 nm, forming a nanocavity estimated to be 20 nm3 and an experimentally measured Q factor of 7.3. A DNA docking strand is designed at the spacer to position a single fluorescent emitter at nanometer accuracy within the cavity. Using Cy5 as a model emitter, a ∼ 30-fold fluorescence enhancement and a significantly reduced emission lifetime (from 1.6 ns to 670 ps) were experimentally verified, confirming significant emitter-cavity interactions. This DR-templated assembly method is capable of fitting AuNRs of variable length-to-width aspect ratios to form anisotropic nanocavities and deterministically incorporate different single emitters, thus enabling flexible design of both cavity resonance and emission wavelengths to tailor light-matter interactions at nanometer scale. [Figure not available: see fulltext.]
Original language | English (US) |
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Pages (from-to) | 1327-1337 |
Number of pages | 11 |
Journal | Nano Research |
Volume | 15 |
Issue number | 2 |
DOIs | |
State | Published - Feb 2022 |
Keywords
- DNA origami
- deterministic single emitter
- nanorod dimer
- optical coupling
- plasmonic nanocavity
- self-assembly
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- General Materials Science
- Condensed Matter Physics
- Electrical and Electronic Engineering