In this work we demonstrate the fabrication and characterization of a temperature insensitive, two-dimensional curvature sensor using a resin based Fabry-Pérot interferometer, constructed using a multicore fiber (MCF). The fabrication simplicity makes this fiber device very attractive compared to the already reported technologies. Furthermore, the sensitivity reached (>400 pm/m^-1), 7 times higher than the one reported for fiber Bragg gratings written on a similar MCF. The reconstruction of the amplitude and curvature has been performed for, showing errors lower than 4%. A numerical study has also been developed, allowing us to understand the sensor response at different fiber sensor geometries.

In this paper, we demonstrate both numerically and experimentally the capability to control and enhance the hydrostatic pressure sensitivity of an adhesive based Fabry-Pérot (FP) sensor. The fiber sensor consists of a polymerized resin in between two single-mode fiber terminals that act as low-reflectance mirrors. The theoretical evaluation of the proposed sensor showed that the strain in the region between the fiber end faces increases with increasing dimensions of the resin structure surrounding the inner FP cavity. Experimentally, the photopolymerizable resin was added in layers, increasing the structure dimensions, allowing to improve the hydrostatic pressure sensitivity from 102 to 475 pm/MPa for the cavity filled with resin just in between the fiber end faces and for the cavity covered with several layers of resin, respectively. The sensor fabrication is simple and cost effective, allowing an easy and affordable way to control and enhance the hydrostatic pressure sensitivity of resin based FP sensors.

The use of long-period gratings (LPGs) to distribute optical power from one core to all the cores in a multicore fiber (MCF) is theoretically analyzed. Simple analytical expressions that describe the mode power’s evolution along the LPGs are derived from the coupled mode equations. This study demonstrated the power transfer between cores in a MCF promoted by identical LPGs. Moreover, with this technique, the pump signal can be distributed to all the cores without interfering with the transmission signals.

In this paper, we propose a new technique to detect the presence of the fiber fuse effect propagation. The implemented technique consists on the utilization of two fiber Bragg gratings (FBGs) as temperature sensors in order to detect the transit of the thermal wave associated with the fuse effect. The developed technique was used to determine the fuse propagation velocity in single mode fibers as function of the injected optical pump power, yielding a direct proportionality constant value of 0.106 ± 0.028 ms^-1W^-1.

In this work is reported the experimental and numerical results of the refractive index response of etched fibre Bragg gratings written in a graded index multimode fibre. The responses of the modes coupled by the grating inscribed in a multimode fibre are compared with the mode coupled by a grating inscribed in single mode fibre. The results of this study show that the refractive index sensitivity and the dynamical range of etched fibre Bragg gratings written in multimode fibres are higher than the ones verified in single-mode fibres. The determination of oil-biodiesel blend concentrations are also compared as an example of practical applications. It is shown that a greater core diameter of the multimode fibre enables the Bragg gratings to exhibit enhanced sensitivity without requiring further fibre diameter reduction.

We propose a technique to inscribe long period gratings (LPGs) in standard single-mode fibers (SSMFs). The proposed method uses a commercial ${\mathrm{CO}}_2$ splicer that allows for the rotation of the fiber during laser irradiation, enabling a uniform exposure around the fiber. LPGs inscribed in SSMFs with different periods are presented. Gratings can be reproduced with a maximum difference between resonant wavelength values of less than 1 nm. Furthermore, it is possible to inscribe gratings with attenuation dips of $-25\mathrm{dB}$ while at the same time obtaining polarization-dependent losses as low as 2 dB.