| 1. |
- Garcia-Ruiz, Andres, et al.
(författare)
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Hermetic Carbon Coatings for Electro-Thermal All-Fiber Phase Modulators
- 2019
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Ingår i: Journal of Lightwave Technology. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0733-8724 .- 1558-2213. ; 37:18, s. 4567-4572
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Tidskriftsartikel (refereegranskat)abstract
- Joule effect and thermal response of several carbon-coated fibers are modeled and analyzed. An electro-thermally driven all-fiber phase modulator based on these principles is proposed and a proof of concept of it is characterized. This kind of fiber could be the basis for developing all-fiber components aimed to operate in environments where the strength increase and impermeability to hydrogen diffusion guaranteed by the carbon coating is crucial.
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| 2. |
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| 3. |
- Magalhães, Regina, et al.
(författare)
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Distributed detection of quadratic Kerr effect in silica fibers using chirped-pulse φoTDR
- 2019
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 9781510631236 - 9781510631243
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Konferensbidrag (refereegranskat)abstract
- Monitoring the presence of external electric fields over large distances and detecting losses along power transmission networks, is of extreme importance nowadays due to concerns with environment, efficiency, cost and safety. In this work, we evaluate a method to achieve distributed measurements of the quadratic electro-optic Kerr effect in silica fibers in a distributed way. For this purpose, we integrate a twin-hole fiber filled with BiSn alloy electrodes and monitor its electric-field induced refractive index (RI) change Δn by using a chirped-pulse phase-sensitive OTDR (CP-ΦOTDR). By exploiting its high sensitivity (RI changes of the order of 10-9), we demonstrate that the proposed system is able to detect the intrinsic quadratic electrooptic nonlinearity (the electric Kerr effect) in the fiber, an effect that is usually considered to be too weak to be exploited for practical applications. Additionally, we show that the CP-ΦOTDR is sufficiently sensitive to measure the electric Kerr effect with untreated standard telecommunication fibers under realistic fields.
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| 4. |
- Magalhaes, Regina, et al.
(författare)
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Fiber-based distributed bolometry
- 2019
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 27:4, s. 4317-4328
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Tidskriftsartikel (refereegranskat)abstract
- Optical fibers are inherently designed to allow no interaction between the guided light and the surrounding optical radiation. Thus, very few optical fiber-based technologies exist in the field of optical radiation sensing. Accomplishing fully-distributed optical radiation sensing appears then as even more challenging since, on top of the lack of sensitivity explained above, we should add the need of addressing thousands of measurement points in a single, continuous optical cable. Nevertheless, it is clear that there exist a number of applications which could benefit from such a distributed sensing scheme, particularly if the sensitivity was sufficiently high to be able to measure correctly variations in optical radiation levels compatible with the earth surface. Distributed optical radiation sensing over large distances could be employed in applications such as Dynamic Line Rating (DLR), where it is known that solar radiation can be an important limiting factor in energy transmission through overhead power cables, and also in other applications such as thermo-solar energy. In this work, we present the proof-of-concept of the first distributed bolometer based on optical fiber technology and capable of detecting absolute changes of irradiance. The core idea of the system is the use of a special fiber coating with high emissivity (e.g., carbon coating or black paint). The high absorption of these coatings translates into a temperature change that can be read with sufficiently high sensitivity using phase-sensitive reflectometry. To demonstrate the concept, we interrogate distinct black-coated optical fibers using a chirped-pulse ÖOTDR, and we readily demonstrate the detection of light with resolutions in the order of 1% of the reference solar irradiance, offering a high-potential technology for integration in the aforementioned applications.
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| 5. |
- Magalhães, Regina, et al.
(författare)
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Towards Distributed Measurements of Electric Fields Using Optical Fibers : Proposal and Proof-Of-Concept Experiment.
- 2020
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 20:16
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Tidskriftsartikel (refereegranskat)abstract
- Nowadays there is an increasing demand for the cost-effective monitoring of potential threats to the integrity of high-voltage networks and electric power infrastructures. Optical fiber sensors are a particularly interesting solution for applications in these environments, due to their low cost and positive intrinsic features, including small size and weight, dielectric properties, and invulnerability to electromagnetic interference (EMI). However, due precisely to their intrinsic EMI-immune nature, the development of a distributed optical fiber sensing solution for the detection of partial discharges and external electrical fields is in principle very challenging. Here, we propose a method to exploit the third-order and second-order nonlinear effects in silica fibers, as a means to achieve highly sensitive distributed measurements of external electrical fields in real time. By monitoring the electric-field-induced variations in the refractive index using a highly sensitive Rayleigh-based CP-φOTDR scheme, we demonstrate the distributed detection of Kerr and Pockels electro-optic effects, and how those can assign a new sensing dimension to optical fibers, transducing external electric fields into visible minute disturbances in the guided light. The proposed sensing configuration, electro-optical time domain reflectometry, is validated both theoretically and experimentally, showing experimental second-order and third-order nonlinear coefficients, respectively, of χ(2) ~ 0.27 × 10-12 m/V and χ(3) ~ 2.5 × 10-22 m2/V2 for silica fibers.
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