Graphene Nano-Optics in the Terahertz Gap

Autor(es)

Feres, Flavio H. ; Barcelos, Ingrid D. ; Cadore, Alisson R. ; Wehmeier, Lukas ; Noerenberg, Tobias ; Mayer, Rafael A. ; Freitas, Raul O. ; Eng, Lukas M. ; Kehr, Susanne C. ; Maia, Francisco C. B.

• Tipo de documento: Artigo Científico
• Fonte: Nano Letters; v. 23, n. 9, p. 8-pg., 2023-05-01.

Resumo

Graphene nano-optics at terahertz (THz) frequencies (nu) is theoretically anticipated to feature extraordinary effects. However, interrogating such phenomena is nontrivial, since the atomically thin graphene dimensionally mismatches the THz radiation wavelength reaching hundreds of micrometers. Greater challenges happen in the THz gap (0.1-10 THz) wherein light sources are scarce. To surpass these barriers, we use a nanoscope illuminated by a highly brilliant and tunable free-electron laser to image the graphene nano-optical response from 1.5 to 6.0 THz. For nu < 2 THz, we observe a metal-like behavior of graphene, which screens optical fields akin to noble metals, since this excitation range approaches its charge relaxation frequency. At 3.8 THz, plasmonic resonances cause a field-enhancement effect (FEE) that improves the graphene imaging power. Moreover, we show that the metallic behavior and the FEE are tunable upon electrical doping, thus providing further control of these graphene nano-optical properties in the THz gap. (AU)

• Processo FAPESP: 22/11987-0 - EMU concedido no processo 2019/14017-9: nanoscópio s-SNOM customizado e aprimorado para operação com IR-THz síncrotron
• Beneficiário: Raul de Oliveira Freitas
• Modalidade de apoio: Auxílio à Pesquisa - Programa Equipamentos Multiusuários
• Processo FAPESP: 22/02901-4 - Nano-óptica de poláritons em cristais bidimensionais e na interface metal/dielétrico no infravermelho médio-distante
• Beneficiário: Francisco Carlos Barbosa Maia
• Modalidade de apoio: Auxílio à Pesquisa - Projeto Inicial
• Processo FAPESP: 19/14017-9 - De ondas de éxcitons a THz-fônons: a nano-óptica de materiais 2Ds via nanoespectroscopia de infravermelho síncrotron
• Beneficiário: Raul de Oliveira Freitas
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 21/10487-0 - EMU concedido no processo 2019/14017-9: unidades de iluminação mid-IR-VIS para s-SNOM síncrotron
• Beneficiário: Raul de Oliveira Freitas
• Modalidade de apoio: Auxílio à Pesquisa - Programa Equipamentos Multiusuários