Control of Plexcitonic Strong Coupling via Substrate‐Mediated Hotspot Nanoengineering. Issue 17 (30th June 2022)

• Record Type: Journal Article
• Authors: Xiong, Xiao; Lai, Yiming; Clarke, Daniel; Kongsuwan, Nuttawut; Dong, Zhaogang; Bai, Ping; Png, Ching Eng; Wu, Lin; Hess, Ortwin
• Is Part Of: Advanced optical materials. Volume 10:Issue 17(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-06-30
• Subjects: antenna modes -- hotspot nanoengineering -- plexcitonic strong coupling -- transition‐metal dichalcogenides -- ultrafast quantum dynamics; Optical materials -- Periodicals; Photonics -- Periodicals; 620.11295
• DOI: 10.1002/adom.202200557
• Languages: English
• ISSNs: 2195-1071

Abstract

Abstract: Plexcitonic strong coupling has ushered in an era of room‐temperature quantum electrodynamics at the nanoscale. Realizing its potential applications from single‐molecule spectroscopy to room‐temperature quantum technologies on an industrial level requires scalable and mass‐producible plasmonic cavities that provide ease of access and control for quantum emitters. Here, a strategy for multidimensional hotspot engineering is proposed via a rational selection of substrates, which facilitates elevation of a gold bowtie nanocavity hotspot to the top of the device and provides a field enhancement of ≈482 (a 1.6‐fold increase compared to a conventional bowtie‐on‐glass cavity at the bottom of the nanogap). The formation mechanism for these antenna modes is discussed from the perspective of charge carrier motion; and their advantages, particularly in view of their dominantly in‐plane polarized near‐fields, are further elaborated in a spatiotemporal study of plexcitonic strong coupling, which reveals ultrafast quantum dynamics and potential for applications related to 2D materials whose excitonic dipoles are typically oriented in‐plane. The conceptual discovery of this substrate‐enabled hotspot nanoengineering could readily be extended to tailor hotspots in other plasmonic platforms, and may inspire a plethora of novel research directions from plasmon‐enhanced spectroscopy and sensing to the design of quantum logic gates and quantum metasurfaces. Abstract : For the canonical gold bowtie, a plasmonic antenna mode with elevated hotspot and in‐plane polarized near‐field can be achieved via a rational selection of the substrate. The extreme plasmon‐mediated field confinement and enhancement of 500‐fold facilitates ultrafast quantum dynamics with quantum emitters in the strong coupling regime, and is particularly appealing for applications related to 2D excitonic quantum materials.