Optically driven plasmons in graphene/hBN van der Waals heterostructures: simulating s-SNOM measurements

Scientific paper - Original scientific paper

• Author: Neven Golenić
• Author: Stefano de Gironcoli
• Author: Vito Despoja
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

Converting transverse photons into longitudinal two-dimensional plasmon-–polaritons (2D-PP) and vice versa presents a significant challenge within the fields of photonics and plasmonics. Therefore, understanding the mechanism which increases the photon – 2D-PP conversion efficiency could significantly contribute to those efforts. In this study, we theoretically examine how efficiently incident radiation, when scattered by a silver spherical nanoparticle (Ag-NP), can be transformed into 2D-PP within van der Waals (vdW) heterostructures composed of hexagonal boron nitride and graphene (hBN/Gr composites). We show that the Dirac plasmon (DP) excitation efficiency depends on the Ag-NP radius as R 3, and decreases exponentially with Ag-NP height h, so that for a certain Ag-NP geometry up to 25 % of the incident electrical field is channeled into the DP. We demonstrate that the linear plasmons (LPs) excitation efficiency can be manipulated by changing the graphene–graphene distance Δ (or hBN thickness) or by changing the number of graphene layers N. By increasing Δ and/or N the LPs move towards smaller wave vectors Q and become accessible by the Ag-NP dipole field, so that for N ≥ 5 the excitation of more than one LP is possible. These results are supported by recent scattering-type scanning near-field optical microscopy (s-SNOM) measurements. Furthermore, we show that Ag-NPs with specific parameters preferentially hybridizes with DPs of a particular wavelength λ D , facilitating selective excitation of DPs. The obtained tuning possibilities could have a significant impact on applied plasmonics, photonics or optoelectronics.

• Keywords (english): s-SNOM; graphene; hBN; photons; optical excitations; Dirac plasmon polariton
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Nanophotonics
• Numbering: vol. 13, no. 15, pp. 2765-2780
• e-ISSN: 2192-8614
• DOI: https://doi.org/10.1515/nanoph-2023-0841
• URN:NBN: urn:nbn:hr:217:244372
• Publication: 2024-07-04
• Project: Number: KK.01.1.1.01.0004; Title (croatian): Provedba vrhunskih istraživanja u sklopu Znanstvenog centra izvrsnosti za kvantne i kompleksne sustave te reprezentacije Liejevih algebri; Title (english): Implementation of top research within the Scientific Center of Excellence for Quantum and Complex Systems, and Representations of Lie Algebras; Acronym: QuantiXLie; Leader: Hrvoje Buljan; Jurisdiction: eu; Funding stream: European Regional Development Fund
• Project: Number: IP-2020-02-5556; Title (croatian): Plazmoni i eksiton-polaritoni u kvazi-2D kristalima; Title (english): Plasmons and exciton-polaritons in quasi-2D crystals; Acronym: 2DPlasEx; Leader: Vito Despoja; Jurisdiction: Croatia; Funding stream: Research Projects
• Document URL: https://www.degruyter.com/document/doi/10.1515/nanoph-2023-0841/html
• Type of resource: Text
• Access conditions: Open access
• Public note: © 2024 the author(s), published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 International License. Received November 23, 2023; accepted March 22, 2024; published online April 15, 2024.
• Created on: 2024-08-01 12:08:20