Publications

Publications by CAP

2018

Optical fiber sensor Mach-Zehnder interferometer based on TiO<inf>2</inf> coated long period fiber grating

Authors
Vasconcelos H.; De Almeida J.M.M.M.; Jorge P.A.S.; Coelho L.;

Publication
Optics InfoBase Conference Papers

Abstract
The wavelength sensitivity and spectral resolution of Mach-Zehnder fiber interferometers based on uncoated and TiO2 coated LPFGs is presented and compared with TiO2 coated single LPFGs optical fiber sensors.

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2018

Plasmonic optical fiber sensor based on double step growth of gold nano-islands

Authors
De Almeida J.M.M.M.; Vasconcelos H.; Jorge P.A.S.; Coelho L.;

Publication
Optics InfoBase Conference Papers

Abstract
Refractive index sensors based on localized surface plasmon resonance are presented through the fabrication of gold nano-islands on top of optical fiber tips. Repeated dewetting process led to an increase of sensitivity from 60 to 186nm/RIU.

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2018

Positioning, Navigation and Awareness of the VAMOS! Underwater Robotic Mining System

Authors
Almeida, J; Martins, A; Almeida, C; Dias, A; Matias, B; Ferreira, A; Jorge, P; Martins, R; Bleier, M; Nuchter, A; Pidgeon, J; Kapusniak, S; Silva, E;

Publication
2018 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS)

Abstract
This paper presents the positioning, navigation and awareness (PNA) system developed for the Underwater Robotic Mining System of the VAMOS! project [1]. It describes the main components of the VAMOS! system, the PNA sensors in each of those components, the global architecture of the PNA system, and its main subsystems: Position and Navigation, Real-time Mine Modeling, 3D Virtual reality HMI and Real-time grade system. General results and lessons learn during the first mining field trial in Lee Moor, Devon, UK during the months of September and October 2017 are presented.

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2018

Optical Fiber Link Failure Prediction System Based on Long-Period Fiber Grating Mechanical Sensor

Authors
Sotomaior, N; Teixeira, B; Azevedo, J; Caldas, P; Rego, G; Pinto, P;

Publication
Proceedings

Abstract
High data rate optical fiber links are usually deployed in core IP networks to transport bulky [...]

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2018

Measurement Thermal Conductivity of Water using a All-Fiber Sensor Based on a Metallic Coated Hybrid LPG-FBG Structure

Authors
E.Silva, G; Caldas, P; Santos, JL; Santos, JC;

Publication
26th International Conference on Optical Fiber Sensors

Abstract

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/RlU was obtained in a low refractive index regime (1.3475-1.3720) with low influence of temperature (-0.32 0.06 pm/degrees C). The cross sensitivity for this structure is 2.0 x 10(-5) RlU/degrees C.. The potential for simultaneous measurement of refractive index and temperature is also studied.

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