CAP - Indexed Articles in Conferences

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    100 km-Ultralong Raman Fiber Laser using a Distributed Rayleigh Mirror for Sensing Applications
    ( 2012) Manuel Joaquim Marques ; Hugo Fidalgo Martins ; Orlando Frazão
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    2D computational modeling of optical trapping effects on malaria-infected red blood cells
    ( 2017) Joana Isabel Paiva ; Ribeiro,RSR ; Pedro Jorge ; Carla Carmelo Rosa ; Guerreiro,A ; João Paulo Cunha
    A computational method for optical fiber trapping of healthy and Malariainfected blood cells characterization is proposed. A trapping force relation with the infection stage was found, which could trigger the development of a diagnostic sensor. © OSA 2017.
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    Acetone evaporation monitoring using a caterpillar-like microstructured fiber
    ( 2015) André Delgado Gomes ; Ferreira,MFS ; Moura,JP ; Ricardo Melo André ; Susana Oliveira Silva ; Kobelke,J ; Bierlich,J ; Wondraczek,K ; Schuster,K ; Orlando Frazão
    A new microstructured optical fiber is demonstrated to detect acetone evaporation by observing the time response of the reflected signal at 1550nm. The sensor consists on a caterpillar-like fiber, with a transversal microfluidic channel created with a Focused Ion Beam technique, spliced to a single-mode fiber. Different stages were visible between the dipping and the evaporation of acetone and of a mixture of water and acetone. It was also possible to detect the presence of water vapor.
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    Adam Hilger revisited: a museum instrument as a modern teaching tool
    ( 2015) Carvalhal,MJ ; Manuel Joaquim Marques
    Spectroscopy can be historically traced down to the study of the dispersion of light by a glass prism. In the early 19th century, inspired by Newton's experiment, Fraunhofer creates a device where an illuminated slit and a lens are placed before the prism; such a device is later transformed, by Kirchoff and Bunsen, into a much handier and more precise observation and measurement instrument, the spectroscope. In the 1930's, the Physics Laboratory of the Faculty of Science of the University of Porto would buy, from Adam Hilger, Ltd., London, a constant deviation spectrometer. The ultimate purpose was to set up a spectroscopy laboratory for teaching and research. This model's robust construction (the telescope and the collimator are rigidly fixed) makes it adequate for student's practice. To sweep across the spectrum, all it takes is to rotate the high quality, constant deviation prism -known as Pellin-Broca prism. Spectra in the 390-900 nm interval are observed, either directly, or through photographic recording, or even by using a thermopile and associated galvanometer, when working in the infra-red range. The wavelength of the line under observation is read straight on a drum, which is fixed to the prism's rotation mechanism. Details of the construction and operation of this spectrometer are explored, against the background of present day spectrometers, automatic and computerized, thereby offering a deeper understanding of spectroscopic analysis: for instance, the use of the raies ultimes powder, a mixture of 50 chemical elements whose emission spectra provide a way of calibrating the instrument.
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    An adjustable sensor platform using dual wavelength measurements for optical colorimetric sensitive films
    ( 2014) Carlos Manuel Machado ; Gouveia,C ; João Ferreira ; Kovacs,B ; Pedro Jorge ; Luís Lopes
    We present a new and versatile sensor platform to readout the response of sensitive colorimetric films. The platform is fully self-contained and based on a switched dual-wavelength scheme. After filtering and signal processing, the system is able to provide self-referenced measures of color intensity changes in the film, while being immune to noise sources such as ambient light and fluctuations in the power source and in the optical path. By controlling the power and the switching frequency between the two wavelengths it is possible to fine tune the output gain as well as the operational range of the sensor for a particular application, thus improving the signal conditioning. The platform uses a micro-controller that complements the analog circuit used to acquire the signal. The latter pre-amplifies, filters and conditions the signal, leaving the micro-controller free to perform sensor linearization and unit conversion. By changing the sensitive film and the wavelength of the light source it is possible to use this platform for a wide range of sensing applications. © 2014 IEEE.
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    Advanced experiments with an Erbium doped fiber laser
    ( 2014) Paulo Vicente Marques ; Manuel Joaquim Marques ; Carla Carmelo Rosa
    This communication describes an optical hands-on fiber laser experiment aimed at advanced college courses. Optical amplifiers and laser sources represent very important optical devices in numerous applications ranging from telecommunications to medicine. The study of advanced photonics experiments is particularly relevant at undergraduate and master level. This paper discusses the implementation of an optical fiber laser made with a cavity built with two tunable Bragg gratings. This scheme allows the students to understand the laser working principles as a function of the laser cavity set-up. One or both of the gratings can be finely tuned in wavelength through applied stress; therefore, the degree of spectral mismatch of the two gratings can be adjusted, effectively changing the cavity feedback. The impact of the cavity conditions on the laser threshold, spectrum and efficiency is analyzed. This experiment assumes that in a previous practice, the students should had already characterized the erbium doped fiber in terms of absorption and fluorescent spectra, and the spectral gain as a function of pump power.
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    Advances in Fs-Laser Micromachining Towards the Development of Optofluidic Devices
    ( 2019) João Miguel Maia ; Vítor Oliveira Amorim ; Daniel Alexandre ; Paulo Vicente Marques ; 4287 ; 4382 ; 6407 ; 6596
    In this chapter the developments made in femtosecond laser micromachining for applications in the fields of optofluidics and lab-on-a-chip devices are reviewed. This technology can be applied to a wide range of materials (glasses, crystals, polymers) and relies on a non-linear absorption process that leads to a permanent alteration of the material structure. This modification can induce, for instance, a smooth variation of the refractive index or generate etching selectivity, which can be used to form integrated optical circuits and microfluidic systems, respectively. Unlike conventional techniques, fs-laser micromachining offers a way to produce high-resolution three-dimensional components and integrate them in a monolithic approach. Recent advances made in two-photon polymerization have also enabled combination of polymeric structures with microfluidic channels, which can provide additional functionalities, such as fluid transport control. In particular, here it is emphasised the integration of microfluidic systems with optical layers and polymeric structures for the fabrication of miniaturized hybrid devices for chemical synthesis and biosensing. © 2019, Springer Nature Switzerland AG.
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    AMINOSQUARYLIUM CYANINES DYES AND EVALUATION OF THEIR EFFECT ON THE PROLIFERATION AND VIABILITY OF HEPG-2 CELLS AND CACO-2 IN CULTURE
    ( 2012) José Ramiro Fernandes ; Sara Guerra ; Amélia Silva ; Lucinda Reis ; Paulo Almeida
    Photodynamic therapy (PDT) is an attractive alternative to the traditional cancer therapies. It involves the administration of a photosensitizing drug that accumulates preferentially in the neoplasic cells, which, by itself, is harmless and has no effect on either healthy or abnormal tissue. PDT photosensitizer candidates must fulfil some requirements, e.g., strong absorption (>105 M-1cm-1) ideally in the so-called 'photodynamic window' (600-850 nm), should be able to generate reactive species such as singlet oxygen in quantitative yields, have minimal dark toxicity and only be cytotoxic when the photosensitizer is irradiated with light of an appropriated wavelength.[1
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    Analysis of a fibre-optic sensor design based on SPR in nanowire metamaterial films
    ( 2014) Leite,IT ; Fernandes,P ; Aurélio Hierro Rodriguez ; Teixeira,JM ; Pedro Jorge ; Ariel Guerreiro
    This paper investigates numerically the performance of a design for an optical sensor of the refractive index of gases and liquids based on smart or functional metamaterial films (smart optical metamembranes).
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    Analysis of Phase Interrogated SPR Fiber Optic Sensors with Different Bimetallic Combinations
    ( 2014) Hamed Moayyed ; Leite,IT ; Luís Carlos Coelho ; José Luís Santos ; Ariel Guerreiro ; Diana Viegas
    Optical fiber sensors based on the phenomenon of plasmonic resonance can be interrogated applying different methods, the most common one being the spectral approach where the measurand information is derived from the reading of the wavelength resonance dip. In principle, a far better performance can be achieved considering the reading of the phase of the light at a specific wavelength located within the spectral plasmonic resonance. This approach is investigated in this work for surface plasmon based fiber optic sensors with overlays which are combinations of bimetallic layers, permitting not only to tune the wavelength of the plasmon resonance but also the sensitivity associated with the phase interrogation of the sensors. The metals considered for the present analysis are silver, gold, copper, and aluminum.
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    Analysis of phase interrogation in SPR-based sensing supported by tapered optical fibres
    ( 2013) Hamed Moayyed ; Leite,IT ; Luís Carlos Coelho ; José Luís Santos ; Diana Viegas
    An analytical model based on geometrical optics and multilayer transfer matrix method is applied to the surface plasmonic resonance supported by fibre taper structures in the context of optical sensing applications. Phase interrogation is considered in particular as a methodology to attain enhanced sensitivities, and the performance of the sensing heads as function of the metal clad and taper parameters is analyzed. General topics concerning the actual relevance of plasmonics are also presented, first in a global perspective and then when applied to sensing.
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    Analysis of phase interrogation of SPR fiber optic sensors with characteristics tailored by the application of different metal-dielectric overlays
    ( 2014) Hamed Moayyed ; Leite,IT ; Luís Carlos Coelho ; José Luís Santos ; Ariel Guerreiro ; Diana Viegas
    Optical fiber sensors based on the phenomenon of plasmonic resonance can be interrogated applying different methods, the most common one being the spectral approach where the measurand information is derived from the reading of the wavelength resonance dip. In principle, a far better performance can be achieved considering the reading of the phase of the light at a specific wavelength located within the spectral plasmonic resonance. This approach is investigated in this work for fiber optic SPR sensors with overlays which are combinations of metallic and dielectric thin films, permitting not only to tune the wavelength of the SPR resonance but also the sensitivity associated with the phase interrogation of the sensors.
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    Analytical Performance of a DNA Aptamer-based for E. coli Detection in Water
    ( 2011) Raquel Barbosa Queirós ; Paulo Vicente Marques
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    Biological Assessment of Lanthanides doepd Hydrxyapatite composites, International Conference on Design of Biomaterials (BIND 2012)- IISc., Bangalore, India, was held on December 9-11, 2012.
    ( 2012) Nandyala Hussain
    International Conference on Design of Biomaterials (BIND 2012)- IISc., Bangalore, India, held on December 9-11, 2012.
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    Brachytherapy radioluminescent fiber sensor: search for infrared radioluminescent materials
    ( 2012) Carla Carmelo Rosa ; Samuel Filipe Chiquita ; Rui Pirraco
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    Bragg Grating Fabrication on Tapered Fiber Tips based on Focused Ion Beam Milling
    ( 2015) Ricardo Melo André ; Becker,M ; Dellith,J ; Rothhardt,M ; Zibaii,MI ; Latifi,H ; Manuel Joaquim Marques ; Bartelt,H ; Orlando Frazão
    Focused ion beam milling is used on chemically etched tapered fiber tips to create fiber Bragg gratings. These fiber Bragg gratings are based on a modulation of silica and external medium. This leads to a wide and structured spectrum obtained due to imperfections and the inherent structure of the tip. The fiber Bragg gratings presented are very short and have a length of 27 mu m and 43 mu m and are milled on the tapered fiber tip. They are characterized in the high temperature range 350-850 degrees C and a sensitivity of 14.4 pm/K is determined.
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    Brillouin Stokes comb generated in a distributed fiber Raman amplifier
    ( 2011) Orlando Frazão ; Hugo Fidalgo Martins ; Manuel Joaquim Marques
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    CAPTURA DE CÉLULAS COM LUZ
    ( 2012) Ariel Guerreiro ; Ana Rita Ribeiro ; Pedro Jorge
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    Cavity ring-down technique for remote sensing A proof-of-concept for displacement measurement
    ( 2016) Susana Oliveira Silva ; Manuel Joaquim Marques ; Orlando Frazão
    This work demonstrates the viability of using a cavity ring-down technique (CRD) for remote sensing. A conventional CRD configuration is used where and optical circulator is added inside the fibre loop to couple 20 km of optical fibre with a gold mirror at its end with the purpose of remote sensing. As a proof-of-concept, an intensity sensor based on an eight-figure configuration is used at the end of the 20 km of fibre for displacement sensing. In this case, a commercial OTDR is used as modulated light source to send impulses down to the fibre ring.