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About

André Gomes completed his master degree in Engineering Physics at the Faculty of Sciences of the University of Porto, Porto, Portugal. He is currently a PhD student in physics, also at the University of Porto. From March to July 2016, he was with the Leibniz Institute of Photonic Technology, in Jena, Germany, with a DAAD scholarship. At the moment, he is with the Center of Applied Photonics at INESC TEC. His research interests include optical fiber sensing, micro and nanofibers, Focused Ion Beam technology and microfiber knot resonators.


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Details

Details

Publications

2018

Temperature independent refractive index measurement using a fiber Bragg grating on abrupt tapered tip

Authors
Gomes, AD; Silveira, B; Warren Smith, SC; Becker, M; Rothhardt, M; Frazao, O;

Publication
Optics and Laser Technology

Abstract
A fiber Bragg grating was inscribed in an abrupt fiber taper using a femtosecond laser and phase-mask interferometer. The abrupt taper transition allows to excite a broad range of guided modes with different effective refractive indices that are reflected at different wavelengths according to Bragg's law. The multimode-Bragg reflection expands over 30 nm in the telecom-C-band. This corresponds to a mode-field overlap of up to 30% outside of the fiber, making the device suitable for evanescent field sensing. Refractive index and temperature measurements are performed for different reflection peaks. Temperature independent refractive index measurements are achieved by considering the difference between the wavelength shifts of two measured reflection peaks. A minimum refractive index sensitivity of 16 ± 1 nm/RIU was obtained in a low refractive index regime (1.3475–1.3720) with low influence of temperature (-0.32 ± 0.06 pm/°C). The cross sensitivity for this structure is 2.0 × 10-5 RIU/°C. The potential for simultaneous measurement of refractive index and temperature is also studied. © 2017 Elsevier Ltd

2018

Cleaved Silica Microsphere for Temperature Measurement

Authors
Gomes, AD; Silveira, B; Dellith, J; Becker, M; Rothhard, M; Bartelt, H; Frazao, O;

Publication
IEEE PHOTONICS TECHNOLOGY LETTERS

Abstract
A sensing structure based on a cleaved silica microsphere is proposed for temperature sensing. The microsphere was cleaved using focused ion beam milling. The asymmetry in the structure introduced by the cut generates not only new cavities but also random interferometric reflections inside the microsphere. These two spectral components can be separated using low-pass and high-pass filters, respectively. The sensor response to temperature can be extracted from the cavities' component using a correlation method. The device achieved a temperature sensitivity of -10.8 +/- 0.2 pm/degrees C between 30 degrees C and 80 degrees C. The same effect is impossible to be obtained in a normal uncleaved microsphere. The random interferometric component did not provide any information on temperature using the same analysis. However, when changing the temperature, a new and completely distinct reflection spectrum with no apparent correlation with others at different temperatures was achieved.

2018

Multipath Interferometer Polished Microsphere for Enhanced Temperature Sensing

Authors
Gomes, AD; Karami, F; Zibaii, MI; Latifi, H; Frazao, O;

Publication
IEEE Sensors Letters

Abstract

2018

The fiber connection method using a tapered silica fiber tip for microstructured polymer optical fibers

Authors
Ferreira, M; Gomes, A; Kowal, D; Statkiewicz Barabach, G; Mergo, P; Frazão, O;

Publication
Fibers

Abstract
In this work, an alternative method of coupling light into microstructured polymer fibers is presented. The solution consists in using a fiber taper fabricated with a CO2 laser. The connection is formed by inserting a tapered silica tip into the holes of a microstructured polymer fiber. This alternative method is duly characterized and the feasibility of such fiber connection to enable the polymer fiber as a displacement sensor is also demonstrated. © 2018 by the authors.

2018

A Brief Review of New Fiber Microsphere Geometries

Authors
Gomes, AD; Monteiro, CS; Silveira, B; Frazao, O;

Publication
Fibers

Abstract