2014
Authors
Ferreira, MS; Bierlich, J; Unger, S; Schuster, K; Santos, JL; Frazao, O;
Publication
JOURNAL OF LIGHTWAVE TECHNOLOGY
Abstract
An interferometric tip sensor based on the post-process of a special design double-cladding optical fiber is proposed. Due to the sensing head design, it is sensitive to environmental variations. In order to analyze this effect, the sensing head is subjected to temperature variations both in liquid and gas (at 1 atm). Comparing the two signals, it is possible to discriminate the contribution of the liquid refractive index variation with temperature. Not only the amplitude of the signal varies with the surrounding medium, but also the phase of the interferometric pattern alters. This is due to the presence of a thin diaphragm at the end face of the fiber structure turning the sensing head in a three wave interferometric device. An indirect measurement of the water refractive index is performed, by subjecting the sensing head to temperature variations in air and water. Even though the sensitivities obtained are lower than the ones reported in the literature, it should be highlighted that there is no core exposition of the fiber to the external medium. The sensor is easy to fabricate, robust, and reproducible.
2014
Authors
Moayyed, H; Leite, IT; Coelho, L; Santos, JL; Guerreiro, A; Viegas, D;
Publication
Latin America Optics and Photonics Conference Laop 2014
Abstract
The recent burst of R&D activity in Plasmonics, associated with the possibility of materials nanostructuring which enables the access to metamaterials, has been strongly impacting many branches of optics such as imaging, data recording and sensing. This talk details the factors that turned the combination Plasmonics and Metamaterials a huge opportunity to optical sensing.© OSA 2014.
2014
Authors
Frazao, O; Ferreira, MS; Andre, RM; Silva, SO; Marques, MB; Santos, JL;
Publication
Optical Sensors, 2014
Abstract
A review in fiber post-processing for sensing applications is presented. The review is divided in three parts. Tapers devices, chemical etching for Fabry-Perot cavities and focused ion beam (FIB) as post-processing applied in optical fibers are considered. The most recent results as sensing elements are shown. © 2014 OSA.
2014
Authors
Silva, GE; Caldas, P; Santos, JC; Santos, JL;
Publication
23RD INTERNATIONAL CONFERENCE ON OPTICAL FIBRE SENSORS
Abstract
In this paper it is presented an all-fiber implementation of the hot-wire needle probe concept, widely used to measure the thermal properties of materials, particularly the thermal conductivity. It is based on the heating of a metal thin film deposited on the surface of the fiber induced by the coupling of laser light into the cladding via a long period grating, and determination, using a fiber Bragg grating, of the time dependence of the temperature of the surrounding medium at a fixed distance of the fiber. The medium considered in this research was the air and the results obtained indicate the feasibility of this approach and point out future developments.
2014
Authors
Moura, JP; Baierl, H; Auguste, JL; Jamier, R; Roy, P; Santos, JL; Frazao, O;
Publication
OPTICS LETTERS
Abstract
A sensing configuration for fluid evaporation monitoring using a suspended-core fiber tip is proposed. Strong differences between the evaporation processes of acetone and isopropyl alcohol were observed, both in terms of the signal's intensity fluctuations and total duration. In each fluid, the main signal variations were due to changes in reflectivity inside a collapsed region of the suspended-core fiber near the spliced interface with a standard single-mode fiber. After further analysis with a wider array of substances, this configuration could, in the future, be used to detect and study the evaporation of different volatile organic compounds. (C) 2014 Optical Society of America
2014
Authors
Silva, SF; Baierl, H; Auguste, JL; Jamier, R; Roy, P; Baptista, JM; Santos, JL; Frazao, O;
Publication
23RD INTERNATIONAL CONFERENCE ON OPTICAL FIBRE SENSORS
Abstract
In this work, an all-fiber loop mirror using a four-bridge silica fiber with a double-Y-shaped suspended-core is presented for the measurement of strain and torsion. The sensing head is formed by a section of the microstructured fiber with 90 mm in length. The fiber loop sensor allowed observing a distinct interference pattern as a result of the geometry of the core fiber. Different sensitivities to strain and torsion were obtained, namely, -5.11 pm/mu e and +/- 1.34 pm/degree.
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