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Details

  • Nationality

    Portugal
  • Centre

    Applied Photonics
  • Contacts

    +351220402301
    helena.s.vasconcelos@inesctec.pt
001
Publications

2019

Spectral Tuning of Long Period Fiber Gratings Fabricated by Femtosecond Laser Micromachining through Thermal Annealing

Authors
Viveiros, D; Almeida, JMMMd; Coelho, L; Vasconcelos, H; Amorim, VA; Maia, JM; Jorge, PAS;

Publication
Proceedings

Abstract
A femtosecond laser direct writing system was developed to explore the fabrication of long-period fiber gratings (LPFGs) in SMF28 fibers. The LPFGs, showing the mode LP1,6 at 1500 nm, were exposed to high-temperature annealing up to 950 °C. Modifications in the refractive index (RI) modulation are observed through a blue-shift in the LPFG attenuation bands and above 850 °C, the mode LP1,7 appear at 1600 nm. The wavelength sensitivity to external RI from 1.300 to 1.452 was estimated for both modes before and after annealing. Greater sensitivity was found for the higher order mode in the entire range reaching 2400 nm/RIU around 1.440.

2019

Mach-Zehnder Interferometers Based on Long Period Fiber Grating Coated with Titanium Dioxide for Refractive Index Sensing

Authors
Soares Guedes Vasconcelos, HCASG; Marques Martins de Almeida, JMMM; Teixeira Saraiva, CMT; da Silva Jorge, PAD; Costa Coelho, LCC;

Publication
Journal of Lightwave Technology

Abstract

2019

Preliminary Study for Detection of Hydrogen Peroxide Using a Hydroxyethyl Cellulose Membrane

Authors
Vasconcelos, H; Almeida, JMMMd; Saraiva, C; Jorge, PAS; Coelho, L;

Publication
Proceedings

Abstract
High concentration of biogenic amines (BA) is an indicator of deterioration of food and the determination of their concentration is an important method of food control. The hydrogen peroxide (H2O2) is a side product of the degradation of BAs by certain enzymes. It is presented an experimental technique grounded on chemiluminescence to measure small quantities of H2O2 with concentrations as low as 0.01%w/w up to 0.08%w/w. Luminol and cobalt hydroxide are added to hydroxyethyl cellulose to obtain an active membrane which will react with the sampling solution and the amount of total light emission is directly related to the H2O2 concentration.

2018

Plasmonic Optical Fiber Sensor Based on Double Step Growth of Gold Nano-Islands

Authors
de Almeida, JMMM; Vasconcelos, H; Jorge, PAS; Coelho, L;

Publication
Sensors

Abstract

2018

Optical fiber sensor Mach-Zehnder interferometer based on TiO2 coated long period fiber grating

Authors
Vasconcelos, H; De Almeida, JMMM; Jorge, PAS; 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. © OSA 2018 © 2018 The Author(s)