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About

About

My main work includes developing integrated solutions towards optimization of femto-etching, direct writing and micromachining using femtosecond based mechanisms which will enable the fabrication of the next-generation compact-size, low-power and intelligent sensing devices. In parallel tasks associated with optical fiber sensors fabrication, assembling and testing have been performed, both in lab and field environments.

Interest
Topics
Details

Details

  • Nationality

    Portugal
  • Centre

    Applied Photonics
  • Contacts

    +351220402301
    carlos.d.viveiros@inesctec.pt
001
Publications

2021

Mach-Zehnder interferometer-based evanescent refractometer inscribed at the surface of Eagle2000 by femtosecond laser writing

Authors
Amorim, VA; Maia, JM; Viveiros, D; Marques, PVS;

Publication
IEEE Sensors Journal

Abstract

2021

Intensity-modulated refractometer based on mode-mismatch in surface waveguides inscribed by femtosecond laser direct writing

Authors
Amorim, VA; Viveiros, D; Maia, JM; Marques, PVS;

Publication
OPTICS AND LASER TECHNOLOGY

Abstract
Optical waveguides were fabricated at the surface of Eagle2000 glass substrates, using femtosecond laser direct writing and wet etching, and their potential as intensity-modulated refractometers was assessed. Through the analysis of their broadband spectral response to different refractive index oils, we observed that mode mismatch is present when the guided mode reaches the surface of the substrate and interacts with the external medium, thus enabling the use of such optical waveguides in refractive index sensing. Refractive indices equal to or greater than that of the substrate also induced a coupling mechanism that was shown not to be suitable in these devices. The device's wavelength of operation was found to be tunable by controlling the distance between the surface and the center of the optical waveguide. However, the sensitivity was seen to diminish by increasing the latter, being nonexistent for distances greater than 5.5 mu m. In this study, the maximum sensitivity values were found for a surface to core center distance between 1 and 2 mu m, in the biological range, and 2.5 to 3 mu m, for a refractive index nearing that of the substrate. Accordingly, maximum sensitivities of approximate to 25 dB/RIU and approximate to 1200 dB/RIU were found between 1.300 < n(D)(25)degrees(C) < 1.400 and 1.490 < n(D)(25)degrees(C) < 1.500, respectively.

2021

Effect of low-doses of gamma radiation on electric arc-induced long period fiber gratings

Authors
Mesonero Santos, P; Fernandez Medina, A; Coelho, LCC; Viveiros, D; Jorge, PA; Belenguer, T; Heredero, RL;

Publication
Sensors

Abstract
This work presents an experimental study on the effects of gamma radiation on Long Period Fiber Gratings (LPFGs) in a low-dose test campaign to evaluate their eventual degradation. The study was carried out with standard single-mode fibers where the grating was inscribed using the Electric-Arc Discharge (EAD) technique. Before the gamma campaign, a detailed optical characterization was performed with repeatability tests to verify the accuracy of the setup and the associated error sources. The gamma-induced changes up to a dose of 200 krad and the recovery after radiation were monitored with the Dip Wavelength Shift (DWS). The results show that the gamma sensitivity for a total dose of 200 krad is 11 pm/krad and a total DWS of 2.3 nm has been observed with no linear dependence. Post-radiation study shows that recovery from radiation-induced wavelength shift is nearly complete in about 4000 h. Experimental results show that the changes suffered under gamma irradiation of these LPFGs are temporary making them a good choice as sensors in space applications. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

2021

Loss mechanisms in femtosecond laser written optical waveguides

Authors
Marques, PVS; Amorim, VA; Maia, JM; Viveiros, D;

Publication
Proceedings of SPIE - The International Society for Optical Engineering

Abstract
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.

2021

Femtosecond laser micromachining of an optofluidics-based monolithic whispering-gallery mode resonator coupled to a suspended waveguide

Authors
Maia, JM; Amorim, VA; Viveiros, D; Marques, PVS;

Publication
SCIENTIFIC REPORTS

Abstract
A monolithic lab-on-a-chip fabricated by femtosecond laser micromachining capable of label-free biosensing is reported. The device is entirely made of fused silica, and consists of a microdisk resonator integrated inside a microfluidic channel. Whispering gallery modes are excited by the evanescent field of a circular suspended waveguide, also incorporated within the channel. Thermal annealing is performed to decrease the surface roughness of the microstructures to a nanometric scale, thereby reducing intrinsic losses and maximizing the Q-factor. Further, thermally-induced morphing is used to position, with submicrometric precision, the suspended waveguide tangent to the microresonator to enhance the spatial overlap between the evanescent field of both optical modes. With this fabrication method and geometry, the alignment between the waveguide and the resonator is robust and guaranteed at all instances. A maximum sensitivity of 121.5 nm/RIU was obtained at a refractive index of 1.363, whereas near the refractive index range of water-based solutions the sensitivity is 40 nm/RIU. A high Q-factor of 10(5) is kept throughout the entire measurement range.