CAP - Indexed Articles in Conferences

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Browsing CAP - Indexed Articles in Conferences by Author "4287"
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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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    Fabrication of Microfluidic Channels by Femtosecond Laser Micromachining and Application in Optofluidics
    ( 2017) João Miguel Maia ; Vítor Oliveira Amorim ; Daniel Alexandre ; Paulo Vicente Marques ; 4287 ; 4382 ; 6407 ; 6596
    Micromachining with femtosecond laser can be exploited to fabricate optical components and microfluidic channels in fused silica, due to internal modification of the glass properties that is induced by the laser beam. In this paper, we refer to the formation of microfluidic channels, where an optimization of the fabrication procedure was conducted by examining etch rate and surface roughness as a function of the irradiation conditions. Microfluidic channels with high and uniform aspect ratio and with smooth sidewalls were obtained, and such structures were successfully integrated with optical components. The obtained results set the foundations towards the development of new optofluidic devices.
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    Fabrication of Monolithic Add-Drop Filters in Pure Silica by Femtosecond Laser Writing
    ( 2018) Paulo Vicente Marques ; Vítor Oliveira Amorim ; João Miguel Maia ; Daniel Alexandre ; Carlos Duarte Viveiros ; 5872 ; 4287 ; 4382 ; 6596 ; 6407
    This paper will review the fabrication of monolithic integrated optical devices by laser direct writing with femtosecond pulsed laser sources, starting with the description of experimental procedures and optimal conditions to fabricate low loss optical waveguides, directional couplers, Y-junctions and first order Bragg gratings by point-by-point writing methods. Finally, the characterization results of a fully operational Add-Drop filter in pure fused silica substrate are described. © 2018 IEEE.
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    Fabrication of periodic structures in optical fibers by femtosecond laser micromachining for sensing applications
    ( 2019) Carlos Duarte Viveiros ; João Miguel Maia ; Vítor Oliveira Amorim ; Pedro Jorge ; Paulo Vicente Marques ; 3565 ; 4287 ; 5872 ; 6407 ; 6596
    A femtosecond laser direct writing system was developed to explore the fabrication of periodic structures in optical fibers. The possibility to write type I first- A nd second-order Bragg gratings in the same single-mode fiber (SMF-28e), with reflectivities of 99.6 % and 59.3 %, respectively, is presented. The fabrication of structures (waveguides and grating) in a coreless and in a SMF-28e fiber was first demonstrated, and the gratings were then exposed to a thermal annealing up to 1000°C. The FBG inscribed in the SMF-28e fiber presents thermal stability at temperatures of 800 °C and a temperature sensitivity of 14.34 pm/°C was determined. © 2019 SPIE.
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    Femtosecond Laser Direct Writing of Turn Around Point Long Period Fiber Gratings Coated with Titanium Dioxide for Improved Sensitivity
    ( 2020) Carlos Duarte Viveiros ; De Almeida,JMMM ; Luís Carlos Coelho ; Vasconcelos,H ; João Miguel Maia ; Amorim,VA ; Pedro Jorge ; Paulo Vicente Marques ; 3565 ; 4287 ; 5256 ; 5872 ; 6596
    The fabrication of Turn Around Point Long Period Fiber Grating in standard SMF-28e fibers through femtosecond laser direct writing is demonstrated and its sensing sensitivity is improved by coating the fiber with titanium dioxide through physical vapor deposition. © 2021 The Author(s).
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    Femtosecond laser micromachining of Fabry-Perot interferometers in SMF-28 fiber for pressure sensing (Conference Presentation)
    ( 2020) Carlos Duarte Viveiros ; José Almeida ; Luís Carlos Coelho ; João Miguel Maia ; Amorim,VA ; Vasconcelos,H ; Pedro Jorge ; Paulo Vicente Marques ; 5256 ; 5799 ; 5872 ; 6596 ; 3565 ; 4287
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    Femtosecond laser micromachining of Fabry-Pérot interferometers in fused silica for refractive index sensing
    ( 2019) João Miguel Maia ; Vítor Oliveira Amorim ; Carlos Duarte Viveiros ; Paulo Vicente Marques ; 4287 ; 5872 ; 6407 ; 6596
    A Fabry-Pérot interferometer was fabricated inside a fused silica substrate through femtosecond laser micromachining. The influence of the waveguide's writing parameters on the measured signal's quality was studied for an interferometer with a 27-µm wide cavity. Optimal signal-to-noise ratio and fringe visibility were obtained for waveguides written at 75 nJ and 50 µm/s. The same device was characterized with different refractive index liquids, and a maximum sensitivity of 1181.4±23.6 nm/RIU was obtained in the index range of 1.2962 to 1.3828 (at 1550 nm) for the spectral order o?'š = 46. © 2019 SPIE.
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    Femtosecond laser-written long period fibre gratings coated with titanium dioxide for improved sensitivity
    ( 2020) Carlos Duarte Viveiros ; José Almeida ; Luís Carlos Coelho ; Vasconcelos,H ; Vítor Oliveira Amorim ; João Miguel Maia ; Pedro Jorge ; Paulo Vicente Marques ; 3565 ; 4287 ; 5256 ; 5799 ; 5872 ; 6407 ; 6596
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    Integrated Optical Devices Fabrication of Multimode Interference Devices in Fused Silica by Femtosecond Laser Direct Writing
    ( 2017) Vítor Oliveira Amorim ; João Miguel Maia ; Daniel Alexandre ; Paulo Vicente Marques ; 4287 ; 4382 ; 6407 ; 6596
    1xN (N=2, 3, 4) MMI power splitters were fabricated in a fused silica substrate by laser direct writing, using a focused 515 nm amplified femtosecond laser beam, and characterized at 1550 nm. To accomplish this, several low loss waveguides were fabricated side by side to form a multimode waveguide with the output in a polished facet of the substrate, while a single low loss waveguide was fabricated to inject light in the centre of the multimode waveguide. The performance of the fabricated devices was optimized by testing three different designs.
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    Loss mechanisms in femtosecond laser written optical waveguides
    ( 2021) Paulo Vicente Marques ; Amorim,VA ; João Miguel Maia ; Carlos Duarte Viveiros ; 4287 ; 5872 ; 6596
    Low loss optical waveguides are the key component for the fabrication of more complex integrated optics devices. In most works related to femtosecond laser written waveguides, the values presented give results at a single wavelength or in a narrow wavelength band; but some applications in optical sensing, for example, would benefit from waveguides having good propagation properties in a larger wavelength range. This paper presents results that allow one to gain insight into the major loss mechanisms present in laser written waveguides in two different types of glasses (fused silica and Eagle 2000 glass) and the dependence of those on the fabrication parameters. Finally, an example of application of broadband operating waveguides is given.
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    Spectral characteristics of optical waveguides fabricated in glass by femtosecond laser direct writing
    ( 2019) Vítor Oliveira Amorim ; Carlos Duarte Viveiros ; João Miguel Maia ; Paulo Vicente Marques ; 4287 ; 5872 ; 6407 ; 6596
    The fabrication of optical waveguides with femtosecond laser direct writing is reported in two materials, Suprasil1 and Eagle2000. The influence of typical fabrication parameters, such as pulse energy and scan velocity, on the waveguide's spectral characteristics is explored from 500 to 1700 nm. Tests conducted in Suprasil1 evidence a strong presence of Rayleigh scattering, hindering the production of low-loss waveguides at short wavelengths. On the other hand, optical waveguides fabricated in Eagle2000 exhibited lower insertion losses at short wavelengths, enabling the fabrication of low-loss broadband optical waveguides with a two order of magnitude higher scan velocity when compared with Suprasil1. © 2019 SPIE.