CAP

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This service develops its activity in the areas of optical sources, optical communications, fiber optic sensors and micro-manufacturing, having facilities for the design and development of electronic systems.

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Browsing CAP by Author "4382"
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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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    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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    Monolithic Add–Drop Multiplexers in Fused Silica Fabricated by Femtosecond Laser Direct Writing
    ( 2017) Vítor Oliveira Amorim ; João Miguel Maia ; Daniel Alexandre ; Paulo Vicente Marques ; 4382 ; 6407 ; 6596 ; 4287
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    Optimization of Broadband Y-Junction Splitters in Fused Silica by Femtosecond Laser Writing
    ( 2017) Vítor Oliveira Amorim ; João Miguel Maia ; Daniel Alexandre ; Paulo Vicente Marques ; 4287 ; 4382 ; 6407 ; 6596
    Optical Y-junction power splitters owe their inherent broadband spectral behavior to their design. However, depending on the fabrication technique employed, asymmetries in the junction might arise, perturbing its performance; this is the case in femtosecond laser written Y-junctions where one arm is typically written over the top of the other. In this letter, the spectral behavior of Y-junctions fabricated in fused silica by the femtosecond laser direct writing technique was analyzed and optimized for the first time, to the best of our knowledge. The junction arms output power balance as well as the corresponding spectral flatness between 1300 and 1600 nm is substantially increased by the implementation of an initial separation between the arms at the junction diverging point, enabling the manufacturing of balanced broadband Y-junctions.
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    Real-Time Optical Monitoring of Etching Reaction of Microfluidic Channel Fabricated by Femtosecond Laser Direct Writing
    ( 2017) João Miguel Maia ; Vítor Oliveira Amorim ; Daniel Alexandre ; Paulo Vicente Marques ; 4287 ; 4382 ; 6407 ; 6596
    Femtosecond laser direct writing is a three dimensional fabrication technique that can be applied to produce integrated optical components with high spatial resolution or microfluidic channels when combined with HF etching. The same fabrication technique can thus be employed to produce monolithic optofluidic devices for sensing applications. One of the most common sensing schemes involves evanescent optical interaction; therefore, the channel must meet some requirements regarding surface roughness, which will depend on the laser writing conditions, as described in this paper. However, of more significance is the distance between waveguiding medium and microfluidic channel that must be accurately defined. This control can be achieved by monitoring the etching reaction of a waveguide grating written a few microns from the channel, as introduced in this paper. In addition to its function as an etching monitor, the grating can also be used as a coarse refractive index sensor device.