(IEEE, 2018) Del Villar, Ignacio; Fuentes Lorenzo, Omar; Chiavaioli, Francesco; Corres Sanz, Jesús María; Matías Maestro, Ignacio; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica; Gobierno de Navarra / Nafarroako Gobernua
Two phenomena for enhancing the sensitivity of longperiod
fiber gratings are combined toward an increase of the sensitivity
to strain of this type of devices: the dispersion turning point
(DTP) and the cladding diameter reduction by an etching process.
The results prove that sensitivities up to 20 pm/με can be attained,
which is a ten-fold improvement compared to the previous works.
The sensitivity in the grating region, which is subjected to etching,
does not depend on the order of the cladding mode responsible for
the attenuation bands generated in the transmission spectrum, but
on the proximity to the DTP for each mode order. On the other
hand, the sensitivity to strain of the global structure, including the
region without etching, can be increased for lower order modes
in a perceptible way if the length of the etched region is smaller
compared to the fiber region under stress. The experimental results
are supported with simulations based on coupled-mode theory and
on FIMMWAVE, which allows understanding the phenomena involved
during the sensing process.
