Dipole modelling for a robust description of subdiffractional polariton waves

Autor(es)

Feres, Flavio H. ^{[1, 2]} ; Barcelos, Ingrid D. ^[1] ; Mayer, Rafael A. ^{[3, 1]} ; dos Santos, Thiago M. ^[1] ; Freitas, Raul O. ^[1] ; Raschke, Markus B. ^{[4, 5]} ; Bahamon, Dario A. ^[6] ; Maia, Francisco C. B. ^[1]

Afiliação do(s) autor(es)

^[1] Brazilian Ctr Res Energy & Mat CNPEM, Brazilian Synchrotron Light Lab LNLS, BR-13083970 Campinas, SP - Brazil

^[2] Sao Paulo State Univ UNESP, Inst Geosci & Exact Sci, Phys Dept, BR-13506900 Rio Claro - Brazil

^[3] Univ Estadual Campinas UNICAMP, Inst Fis Gleb Wataghin, Campinas, SP - Brazil

^[4] Univ Colorado, JILA, Boulder, CO 80309 - USA

^[5] Univ Colorado, Dept Chem, Dept Phys, Boulder, CO 80309 - USA

^[6] Univ Prebiteriana Mackenzie, MackGraphe Graphene & Nanomat Res Ctr, BR-01302907 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: NANOSCALE; v. 11, n. 44, p. 21218-21226, NOV 28 2019.
• Citações Web of Science: 0

Resumo

The nanophotonics of van der Waals (vdW) materials relies critically on the electromagnetic properties of polaritons defined on sub-diffraction length scales. Here, we use a full electromagnetic Hertzian dipole antenna (HDA) model to describe the hyperbolic phonon polaritons (HP(2)s) in vdW crystals of hexagonal boron nitride (hBN) on a gold surface. The HP2 waves are investigated by broadband synchrotron infrared nanospectroscopy (SINS) which covers the type I and type II hyperbolic bands simultaneously. Basically, polariton waves, observed by SINS, are assigned to the resultant electric field from the summation over the irradiated electric fields of dipoles distributed along the crystal edge and at the tip location and a non-propagating field. The values of polariton momenta and damping extracted from the HDA model present excellent agreement with theoretical predictions. Our analysis shows that the confinement factor of type I HP(2)s exceeds that of the type II ones by up to a factor of 3. We extract anti-parallel group velocities (v(g)) for type I (v(g,typeI) = -0.005c, c is the light velocity in a vacuum) in relation to type II (v(g,typeII) = 0.05c) polaritonic pulses, with lifetimes of similar to 0.6 ps and similar to 0.3 ps, respectively. Furthermore, by incorporating consolidated optical-near field theory into the HDA model, we simulate real-space images of polaritonic standing waves for hBN crystals of different shapes. This approach reproduces the experiments with a minimal computational cost. Thus, it is demonstrated that the HDA modelling self-consistently explains the measured complex-valued polariton near-field, while being a general approach applicable to other polariton types, like plasmon- and exciton-polaritons, active in the wide range of vdW materials. (AU)

• Processo FAPESP: 18/05425-3 - Efeito de cavidade de Fônons-Polaritons em heteroestruturas bidimensionais de Grafeno-Nitreto de boro hexagonal
• Beneficiário: Flávio Henrique Feres
• Linha de fomento: Bolsas no Brasil - Mestrado
• Processo FAPESP: 15/11779-4 - Efeitos plasmônicos e não-lineares em grafeno acoplado a guias de onda ópticos
• Beneficiário: Christiano José Santiago de Matos
• Linha de fomento: Auxílio à Pesquisa - Temático
• Processo FAPESP: 19/08818-9 - Modulação de amplitude de polaritons por barreiras dielétricas bidimensionais sob a luz da nanoespectroscopia de infravermelho síncrotron
• Beneficiário: Rafael Alves Mayer
• Linha de fomento: Bolsas no Brasil - Mestrado
• Processo FAPESP: 18/07276-5 - Biodetecção plasmônica no infra-vermelho médio e longínquo usando grafeno
• Beneficiário: Christiano José Santiago de Matos
• Linha de fomento: Auxílio à Pesquisa - Regular