Open AccessNegative axial strain sensitivity in gold-coated eccentric fiber Bragg gratings
Author(s) -
Karima Chah,
Damien Kinet,
Christophe Caucheteur
Publication year - 2016
Publication title -
scientific reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.24
H-Index - 213
ISSN - 2045-2322
DOI - 10.1038/srep38042
Subject(s) - fiber bragg grating , materials science , cladding (metalworking) , optics , long period fiber grating , cladding mode , femtosecond , laser , wavelength , resonance (particle physics) , optoelectronics , optical fiber , fiber optic sensor , physics , polarization maintaining optical fiber , particle physics , metallurgy
New dual temperature and strain sensor has been designed using eccentric second-order fiber Bragg gratings produced in standard single-mode optical fiber by point-by-point direct writing technique with tight focusing of 800 nm femtosecond laser pulses. With thin gold coating at the grating location, we experimentally show that such gratings exhibit a transmitted amplitude spectrum composed by the Bragg and cladding modes resonances that extend in a wide spectral range exceeding one octave. An overlapping of the first order and second order spectrum is then observed. High-order cladding modes belonging to the first order Bragg resonance coupling are close to the second order Bragg resonance, they show a negative axial strain sensitivity (−0.55 pm/με) compared to the Bragg resonance (1.20 pm/με) and the same temperature sensitivity (10.6 pm/°C). With this well conditioned system, temperature and strain can be determined independently with high sensitivity, in a wavelength range limited to a few nanometers.