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About

Graduated in Physics - Optics from the University of Minho (1999), he obtained a Masters in Optoelectronics and Laser from Faculty of Science from University of Porto (2003), a PhD in Physics from Faculty of Science from University of Porto (2011). He is Associate Professor in Instituto Politécnico de Viana do Castelo and Senior Researcher at the Applied Photonics Center INESC TEC. It is author and co-author of over 80 scientific articles related to optical fibers sensors, whispering gallery modes and long period grating.

Interest
Topics
Details

Details

  • Nationality

    Portugal
  • Centre

    Applied Photonics
  • Contacts

    +351220402301
    paulo.caldas@inesctec.pt
Publications

2020

Micro-force measurement with pre-curvature long-period fiber grating-based sensor

Authors
Ferreira, WSJ; dos Santos, PSS; Caldas, P; Jorge, PAS; Sakamoto, JMS;

Publication
EPJ Web of Conferences

Abstract
In this work, a long-period fiber grating (LPG) based sensor was evaluated as a sensing device for micro-force measurement, in the order of micro Newtons. It was used an LPG fabricated by arc-inducted technique in a SMF-28 standard optical fiber. The optical fiber was fixed between two clamps with a separation of 150 mm with the middle of the LPG located at the center. Characterizations were performed in terms of temperature, curvature and strain. The grating was then used as a micro-force sensor by means of both curvature and strain, induced by a hung mass in a stretched fiber. Furthermore, the evaluation of a precurvature LPG was performed to assess if an increase of sensitivity is achieved. Micro-force sensitivity achieved with the stretched LPG was 1.41 nm/mN and it was demonstrated that its sensitivity can be enhanced to 5.14 nm/mN with a pre-curvature of 2.2 m–1 applied to the LPG, achieving a spectral resolution of at least 15.6 µN.

2020

Sensor Based on Multiple Fiber Bragg Gratings for Diameter Measurement

Authors
Cardoso, V; Caldas, P; Thereza, MGR; Frazão, O; Carvalho, C; Costa, J; Santos, JL;

Publication
EPJ Web of Conferences

Abstract
A method based on multiple Fiber Bragg Gratings (FBG) and a structure fabricated using a 3D printer for diameter measurement is proposed and experimentally demonstrated. The sensor is easily developed inserting the FBG on the structure and fixing the FBG in two points. Due to this arrangement, when the diameter is reduced a force is applied on the sensor and this causes a wavelength shift. The study is divided in two steps using one experimental setup. At first, each FBG response is independently evaluated concerning the diameter variation and after that, the FBGs are evaluated together. The results demonstrated that the structure can be used as a way to monitor the diameter variation in some applications.

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 [...]

2018

Measurement thermal conductivity of water using a all-fiber sensor based on a metallic coated hybrid LPG-FBG structure

Authors
Silva, GE; Caldas, P; Santos, JL; Santos, JC;

Publication
Optics InfoBase Conference Papers

Abstract
This paper presents preliminary results of common water thermal conductivity measurements using an all-fiber sensor based in conventional hot-wire method concept. The thermal conductivity of common water at room temperature obtained is 0.699 W/mK. Although the result is relatively distinct, about 14%, from the reference value found in literature, it is promising and indicates the feasibility of using the experimental arrangement for measuring thermal properties of materials with higher accuracy, provided that improvements already foreseen in future work be incorporated. © OSA 2018 © 2018 The Author(s)

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