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1,501 results on '"Kalli, Kyriacos"'

166. Characterization of an instrumented GeoStrap® with plastic optical fiber bragg gratings

Author

Aressy, Matthieu, Bennani, Yassine, Lacraz, Amédéé, and Kalli, Kyriacos

Subjects
Geosynthetic, Pull-out, FBG, Optical sensor, Engineering and Technology, Tensile, POF, Electrical Engineering - Electronic Engineering - Information Engineering
Abstract

Polymer Optical Fibres (POF) sensors have attracted significant interest in the field of earthwork structure monitoring mainly due to their high elongation capability in contrast to traditional glass optical fibres (GOF). Recent development in the POF field have shown that it is now possible to inscribe fibre Bragg gratings (FBGs) in low loss perfluorinated POF (POFBG). The perfluorinated fibres, such as CYTOP, have losses in the near infrared, at 1550nm that are approximately 0.2dB/m. CYTOP is extremely transparent as it exhibits low scattering loss due to its highly amorphous nature and low optical absorption because of the perfluorinated backbone that shift the optical losses to the infrared, at 7.7–10μm. However, it is precisely this improved loss performance that hinders the laser inscription of basic optical components such as FBGs in CYTOP; in contrast PMMA has an absorption feature that peaks at close to 325nm, which enables laser-induced material modifications using a HeCd laser. The excellent transparency of CYTOP makes it suitable for use with femtosecond laser direct write methods. We inscribe a complex FBG sensor array in CYTOP fibre and show that this robust and smart sensing strand is compatible with coating methods that are used in the geosynthetic industry. This new development extends the possibility of instrumentation from distributed strain measurements alone to potential local load, strain, temperature or pressure measurements. In this paper, the authors will present the manufacturing process of an instrumented GeoStrap® and the associated characterization using standard geosynthetic testing such as tensile test and pull-out test. The results obtained will be discussed and the prospects presented. © 2018 11th International Conference on Geosynthetics 2018, ICG 2018. All rights reserved.

Published
2018

167. Laser-sculpted hybrid photonic magnetometer with nanoscale magnetostrictive interaction

Author

Allsop, Thomas, Lee, Graham B., Wang, Changle, Neal, Ronald, Kalli, Kyriacos, Culverhouse, Philip, and Webb, David J.

Subjects
Magnetostrictive material, Long period gratings, Optical sensing, Physics::Optics, Engineering and Technology, Magnetic sensors, Electrical Engineering - Electronic Engineering - Information Engineering
Abstract

We present a new photonic magnetic sensor that can yield information on the spatial angle of rotation of the sensor within a given static magnetic field that based upon an optical fiber platform that has a wavelength-encoded output and a demonstrated sensitivity of 543 pm/mT. This optical fiber magnetic field sensor combines a conventional, UV-laser inscribed long period grating (LPG) with a magnetostrictive material Terfenol-D that coats and fills 50-μm micro-slots running adjacent and parallel to the fiber central axis. The micro-slots are produced using a femtosecond laser and selective chemical etching. A detection limit for a static magnetic field strength of ±50 μT is realized in low strength DC magnetic field (below 0.4 mT), this performance approaches the Earth's magnetic field strength and thus, once optimized, has potential for navigation applications. Our method addresses the major drawback of conventional sensors, namely their inadequate sensitivity to low strength, static magnetic fields and their inability to provide information about the orientation and magnitude.

Published
2018

187. Quasi-Distributed Torque and Displacement Sensing on a Series Elastic Actuator’s Spring Using FBG Arrays Inscribed in CYTOP Fibers

Author

Leal-Junior, Arnaldo G., primary, Theodosiou, Antreas, additional, Min, Rui, additional, Casas, Jonathan, additional, Diaz, Camilo R., additional, Dos Santos, Wilian M., additional, Pontes, Maria Jose, additional, Siqueira, Adriano A. G., additional, Marques, Carlos, additional, Kalli, Kyriacos, additional, and Frizera, Anselmo, additional

Published
2019
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194. Surface nanoscale axial photonics structures introduced by bending of optical fibers

Author

Bunge, Christian-alexander, Kalli, Kyriacos, Mendez, Alexis, Bochek, Daria, Sumetsky, Misha, Vatnik, Ilya, Toropov, Nikita, Han, Zhiyong, Bunge, Christian-alexander, Kalli, Kyriacos, Mendez, Alexis, Bochek, Daria, Sumetsky, Misha, Vatnik, Ilya, Toropov, Nikita, and Han, Zhiyong

Abstract

The new manufacturing method for fabrication of Surface Nanoscale Axial Photonics (SNAP) structures has been developed. We showed experimentally that the bent fiber can achieve the nanometer-scale variation in the effective fiber radius sufficient for fabrication of SNAP microresonators. The advantage of the demonstrated method is in its simplicity, robustness, and mechanical tunability of the fabricated devices.

Published
2018

195. L-band CYTOP Bragg gratings for ultrasound sensing

Author

Broadway, Christian, Kalli, Kyriacos, Theodosiou, Andreas, Zubel, Michal, Sugden, Kate, Megret, Patrice, Caucheteur, Christophe, Broadway, Christian, Kalli, Kyriacos, Theodosiou, Andreas, Zubel, Michal, Sugden, Kate, Megret, Patrice, and Caucheteur, Christophe

Abstract

Polymer optical fibre (POF) has been receiving increasing attention for sensing applications. The fundamental properties of POF such as PMMA deliver at least an order of magnitude in improvements over silica fibres, though practical difficulties create additional complexity. POF has the potential to deliver lower acoustic impedance, a reduced Young's Modulus and a higher acoustic sensitivity within the megahertz region. In contrast, existing piezo-electric transducers have an inherent narrow acoustic bandwidth and a proportionality to size that causes difficulties for applications such as endoscopy within the biomedical domain. POF generally suffers high attenuation per kilometre at telecommunications wavelengths, limiting fibre lengths to mere centimetres. However, CYTOP, a graded index perfluorinated polymer, is a commercially certified product allowing the use of telecoms region technology and tens of meters of fibre without exceeding acceptable losses. With an effective refractive index between 1.32 and 1.33, it is fundamentally better placed for applications using water or a similar media for acoustic coupling. We demonstrate ultrasonic detection at 5,10 and 15 MHz using a TFBG within a CYTOP fibre in the telecoms region and the latest knowledge in POF handling and connectorisation. This first step in the use of CYTOP demonstrates the viability of the sensor and paves the way towards further advances towards its eventual application.

Published
2018

196. Manufacturing and characterization of asymmetric evanescent field polished couplers for grating assisted mode selective fiber coupling

Author

Bunge, Christian-Alexander, Kalli, Kyriacos, Mendez, Alexis, Schlangen, Sebastian, Bremer, Kort, Zheng, Yulong, Isaak, Andreas, Wurz, Marc Christopher, Böhm, Sebastian, Wellmann, Felix, Steinke, Michael, Pelegrina Bonilla, Gabriel, Neumann, Jörg, Kracht, Dietmar, Roth, Bernhard, Overmeyer, Ludger, Bunge, Christian-Alexander, Kalli, Kyriacos, Mendez, Alexis, Schlangen, Sebastian, Bremer, Kort, Zheng, Yulong, Isaak, Andreas, Wurz, Marc Christopher, Böhm, Sebastian, Wellmann, Felix, Steinke, Michael, Pelegrina Bonilla, Gabriel, Neumann, Jörg, Kracht, Dietmar, Roth, Bernhard, and Overmeyer, Ludger

Abstract

Mode division multiplexing (MDM) could bring a technological progress in the field of optical telecommunication by increasing the data transmission bandwidth. A key challenge for enabling MDM lies in manufacturing of efficient and cost-effective mode-selective fiber couplers. The fiber grating based mode selective coupling approach is a method that is currently being under research in this context. In this work a novel process for manufacturing of asymmetric evanescent field polished couplers is presented which enables grating assisted mode selective coupling. In addition, we discuss the optical setup developed for characterization of these couplers.

Published
2018

198. Femtosecond laser inscription of Bragg and complex gratings in coated and encapsulated silica and low-loss polymer optical fibers

Author

Kalli, Kyriacos, Lacraz, A., Polis, M., Othonos, Andreas S., Kalinowski H.J., Fabris J.L., Bock W.J., Othonos, Andreas S. [0000-0003-0016-9116], and Kalli, Kyriacos [0000-0003-4541-092X]

Subjects
Complex gratings, All-silica fiber, Femtosecond laser inscription, PHOSFOS, Materials science, Polymers, Fiber cores, Physics::Optics, Superstructure gratings, Ultrashort pulses, Plastic optical fibers, Optics, Femtosecond laser inscriptions, Fiber Bragg grating, Fiber optic sensors, Fiber laser, Fiber Bragg gratings, Optical fibers, Physics::Atomic Physics, Plastic optical fiber, business.industry, Optical fiber sensors, Bragg gratings, Silica, Optical fiber pressure sensors, Long-period fiber grating, Fibers, Condensed Matter::Soft Condensed Matter, Polymer optical fiber, Optoelectronics, Wavelength filters, business, Plastic coatings, Hard-clad silica optical fiber, Low-loss, Photonic-crystal fiber
Abstract

The development of wavelength filters, such as Bragg and superstructure gratings in glass and polymer optical fibers, using a femtosecond laser is reported. By using a femtosecond laser operating in the green, which offers greater inscription efficiency, we demonstrate the reliable inscription of Bragg and superstructure gratings in coated silica and low-loss CYTOP polymer optical fibers. We employ line by line and point by point inscription methods, allowing for multiple and overlapping gratings in the fiber core. Moreover, we demonstrate a novel fibre Bragg grating inscription technique to modify and add versatility to an existing, encapsulated optical fiber pressure sensor. © 2015 SPIE. 9634 Sponsors: Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) et al. FBGS Innovative Economy - National Cohesion Strategy OZ Optics Conference code: 115933 Cited By :1

Published
2015

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