2006
Autores
Baptista, JM; Marques, JM; Frazao, O; Santos, S; Santos, JL; Marques, MB;
Publicação
Optics InfoBase Conference Papers
Abstract
An optical fibre intensity sensor referenced by stimulated Brillouin scattering is presented. The sensor uses Fresnel reflection at the sensor fibre end and employs an adequate relationship between Brillouin and Rayleigh scattering and Fresnel reflection. © 2006 OSA/OFS 2006.
2006
Autores
Frazao, O; Marques, JM; Santos, JL; Marques, MB; Baptista, JM;
Publicação
Optics InfoBase Conference Papers
Abstract
In this work, a Brillouin fibre laser sensor for strain and temperature discrimination is presented. The fibre laser sensor consists in a Fabry-Pérot cavity with 20 meters of optical fibre between two Bragg gratings. © 2006 OSA/OFS 2006.
1998
Autores
Baptista, JM; Santos, JL; Lage, AS;
Publicação
OPTICAL AND FIBER OPTIC SENSOR SYSTEMS
Abstract
A theoretical and experimental study of the self-referencing resonant fiber optic intensity sensors based respectively on Michelson and Mach-Zehnder configurations is conducted. Sensor linearity and sensitivity are addressed, being also considered sensors design and optimization.
2009
Autores
Montero, DS; Vazquez, C; Baptista, JM; Santos, JL;
Publicação
Proceedings of SPIE - The International Society for Optical Engineering
Abstract
A novel self-referencing parameter for electro-optical WDM networks in reflective configuration for remote fiber-optic intensity sensors is reported and experimentally tested. In this configuration electrical delay lines are deployed at the processing unit, instead of long delay fiber coils in each measuring point; providing a more compact sensor-head and an easy-reconfigurable operation point. The measurement parameter is defined as the ratio between voltage values at the reception stage for different electrical phase-shifts and it is analyzed following the Z-transform formalism. Measurements validating the theoretical model are reported and self-referencing and crosstalk properties of the network are analyzed. © 2009 SPIE.
2008
Autores
Frazao, O; Baptista, JM; Santos, JL; Kobelke, J; Schuster, K;
Publicação
ELECTRONICS LETTERS
Abstract
The study of the strain and temperature characteristics of a sensing head based on a four-hole suspended-core fibre in a Sagnac interferometric configuration is reported. It is shown that, for the case of using an uncoated suspended-core fibre, a relatively large strain sensitivity is obtained (similar or equal to 1.94 pm/mu epsilon), while the temperature sensitivity is small (similar or equal to 0.29 pm/degrees C), pointing to a temperature-independent strain sensor. When the fibre is coated, the strain sensitivity remains essentially the same, while the temperature sensitivity becomes much larger and with a value that changes with the localisation of the temperature variation range.
2007
Autores
Frazao, O; Marques, L; Marques, J; Baptista, JM; Santos, JL;
Publicação
Third European Workshop on Optical Fibre Sensors
Abstract
This work presents a temperature independent strain/load sensor using a highly birefringent photonic crystal fibre loop mirror. The length of the sensing head is 38 centimetres and its corresponding wavelength spacing between two interferometer minima is 8 nm. The obtained strain and transverse load sensitivity were 1.21 pm/mu epsilon and 0.37 nm/Kg/mm, respectively, while is insensitive to temperature (0.3 pm/degrees C).
The access to the final selection minute is only available to applicants.
Please check the confirmation e-mail of your application to obtain the access code.