Autor(es)

Li, Kezheng ; Martins, Augusto ; Bohora, Sanket ; Dhakal, Ashim ; Martins, Emiliano R. ; Krauss, Thomas F.

• Tipo de documento: Artigo Científico
• Fonte: ADVANCED OPTICAL MATERIALS; v. N/A, p. 7-pg., 2023-07-03.

Resumo

The advantages of metalenses to enable miniaturized systems have been well established, especially in the visible and infrared wavelength regimes. The ultraviolet (UV) presents a final frontier because feature size scales as the wavelength, so realizing a large size metalens with a high numerical aperture (NA) in the UV is a major challenge. Here, a single-layer, thin-film (450 nm) hybrid metalens with an NA of 0.9 and a diameter of 6.2 mm is presented. By combining a Fresnel lens and optimised binary gratings, the well-known shadowing effect of Fresnel lenses at high NA is avoided while being able to realize a large area lens. It is demonstrated that the combination of high NA and large area affords efficient detection of tryptophan-like fluorescence, which is a well-studied proxy for water contamination with faecal coliforms. The detection of tryptophan at levels better than 1 ppb, which corresponds to the low-risk category for drinking water according to the World Health Organization (WHO), is shown. It is also confirmed that the hybrid metalens fluorescence collection efficiency is 3.5 times higher than a high NA plano-convex lens used in state-of-the-art fluorometers, which demonstrates that the versatile metalens approach opens up new opportunities in the UV. (AU)

• Processo FAPESP: 20/00619-4 - Metasuperfícies para imageamento e sensoriamento
• Beneficiário: Emiliano Rezende Martins
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 21/06121-0 - Propagação de ondas eletromagnéticas em estruturas complexas
• Beneficiário: Ben-Hur Viana Borges
• Modalidade de apoio: Auxílio à Pesquisa - Regular