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Projeto de investigação
Photonic biosensor for point of care and early diagnostics of acute kidney injury
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Cross-section mismatch
Publication . Lourenço, Paulo; Fantoni, Alessandro; Costa, João; Vieira, Manuela; DEE - Departamento de Engenharia Electrotécnica e de Computadores; Elsevier
Coupling light into and/or out of a photonic integrated circuit is often accomplished by establishing a vertical link between a single-mode optical fiber and a resonant waveguide grating, which is then followed by a tapered and a single-mode waveguides. The tapered waveguide operates as a spot-size converter, laterally expanding or contracting the light beam between the single-mode waveguide and the resonant waveguide grating. In this work, we propose using subwavelength structures to achieve tapering functionalities. To this end, we designed a metamaterial structure that enables the modulation of the refractive index necessary to either expand or focus a beam of light. Furthermore, we simulated the metamaterial structure through adequate numerical methods and the expanding, and focusing performances were analyzed in terms of efficiency and mode profile matching. We achieved over 43 % and 48 % for the integral overlap with the transverse magnetic fundamental mode for the focusing and expanding configurations, respectively, out of 49 % and 51 % of power transferred.
An indium-oxide electrode with discontinuous Au layers for plasmonic devices
Publication . Vygranenko, Yuri; Lavareda, Guilherme; André, Vânia; Brogueira, Pedro; Amaral, Ana; Fernandes, Miguel; Fantoni, Alessandro; Vieira, M.; CTS - Centro de Tecnologia e Sistemas; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; DCM - Departamento de Ciência dos Materiais
In this contribution we report on a low cost plasmonic electrode for light-sensing applications. The electrode combines a conducting nonstoichiometric indium oxide (InOx) layer with an ultrathin (∼5 nm) discontinuous Au layer. The InOx and Au layers were deposited on glass substrates by plasma enhanced reactive thermal evaporation and thermal evaporation, respectively. Several device configurations with one or two Au layer(s) sandwiched between InOx layers were fabricated and characterized. The morphological and structural properties of both Au and InOx layers were analyzed using AFM and XRD techniques. In particular, the effect of thermal annealing (673 K, 15 min) on the surface morphology of Au layers grown on bare glass and InOx-coated substrate was investigated. It has been also found that the oxide film grown above an underlying nanostructured Au layer is amorphous, while a reference InOx film on glass is nanocrystalline with a smooth surface. The electrical properties of InOx grown on the Au surface are worsened due to Au-induced structural disorder. The observed difference in transmission spectra of the glass/InOx/Au and glass/Au/InOx structures indicates the difference in the morphology of the metal layer. Thus, the optical and morphological properties of the InOxelectrode can be varied in a wide range by incorporating several Au layers.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
9471 - RIDTI
Número da atribuição
PTDC/NAN-OPT/31311/2017