Abstract
A clamp-on optical current sensor prototype for metering and protection applications in high power systems was developed and characterized. The system is based on the Faraday effect in a low birefringence, high Verdet constant, 8cm long SF57 Schott glass prism. It was incorporated in a nylon casing suitable for clamp-on applications in the power line. The sensor operation was tested at 630nm, 830nm, and 1550nm to access its applicability in remote interrogation via fiber links. Optimal operation at 830nm is reported with a linear response up to 65.28kA, with 0.1 or 0.2 accuracy class considering a nominal currents of 1.2 and 0.3 kA (root mean square), respectively. Twelve calibrations procedures performed over six days showed an estimated maximum error of 11m A. Preliminary measurements were made from 40 to 400Hz. The sensor was exposed to transient signals less than 10 mu s that demonstrated its use in protection applications.

Abstract
In this work, spiral phase lenses and Fresnel zone lenses for beam tailoring, fabricated on the tip of optical fibers, are reported. The spiral phase lenses allow tailoring the fundamental guided mode, a Gaussian beam, into a Laguerre - Gaussian profile without using additional optical elements. Whereas, the Fresnel lenses are used as focusing systems. The lenses are fabricated using Focused Ion Beam milling, enabling high resolution in the manufacturing process. The output optical intensity profiles matching the numerical simulations are presented and analyzed.

Abstract
This work demonstrates the viability of using a cavity ring-down technique (CRD) for remote sensing. A conventional CRD configuration is used where and optical circulator is added inside the fibre loop to couple 20 km of optical fibre with a gold mirror at its end with the purpose of remote sensing. As a proof-of-concept, an intensity sensor based on an eight-figure configuration is used at the end of the 20 km of fibre for displacement sensing. In this case, a commercial OTDR is used as modulated light source to send impulses down to the fibre ring.

Abstract
The effect of an erbium-doped fiber amplifier (EDFA) placed inside the fiber ring of a cavity ring down (CRD) configuration is studied. The limitations and advantages of this configuration are discussed, and the study of the ring-down time as a function of the current applied and gain to the EDFA is also presented. In this case, the power fluctuations in the output signal are strongly dependent on the cavity ring-down time with the EDFA gain.

Abstract
The ability to detect and quantify small amounts of DNA in biological complex samples is a hot research area. Up until recently most of the work performed in this area used label-dependent protocols that increases its complexity and overall costs. The aim the work was to develop a label-free technology suitable for DNA detection and quantification using real complex DNA samples. The applicability of this system was tested using synthetic ssDNA targets that guaranteed the systems specificity, in the sense that only complementary sequences hybridized with the probe. When using real samples extracted from Vitis vinifera L. the system was able to successfully detect and quantify the DNA present without any of the time consuming and costly amplification steps. The detection and quantification limits of the proposed system were 60 +/- 20 nM and 201 +/- 20 nM, respectively for Target 1 concentrations between 31 and 350 nM. This method can easily be applied to other species and purposes, allowing the direct detection of DNA in a label-free environment with high accuracy and specificity.

Abstract
The detection of volatile organic compounds is accomplished with a sensing device based on a long period fiber grating (LPFG) coated with a zinc oxide (ZnO) thin layer with self-temperature compensation. The ZnO coating structure was produced onto the cladding of the fiber by thermal oxidation of a metallic Zn thin film. The morphological characterization of ZnO thin films, grown at the same time on silicon substrates, was performed using X-ray diffraction, X-ray Photoelectron Spectroscopy and Scanning Electron Microscope which shows very good agreement. LPFGs with 290 nm thick ZnO coating were fabricated and characterized for the detection of ethanol and hexane in vapor phase. For ethanol a sensitivity of 0.99 nm / g.m(-3) was achieved when using the wavelength shift interrogation mode, while for hexane a much lower sensitivity of 0.003 nm / g.m(-3) was measured, indicating a semi-selectivity of the sensor with a spectral resolution better than 3.2 g.m(-3).