Abstract
This Letter reports a new method for the generation of optical vortices using a micropatterned optical fiber tip. Here, a spiral phase plate (2 pi phase shift) is micromachined on the tip of an optical fiber using a focused ion beam. This is a high resolution method that allows milling the fibers with nanoscale resolution. The plate acts as a beam tailoring system, transforming the fundamental guided mode, specifically a Gaussian mode, into the Laguerre-Gaussian mode (LG(01)), which carries orbital angular momentum. The experimental results are supported by computational simulations based on the finite-difference time-domain method. (C) 2016 Optical Society of America

Abstract
In this manuscript we present a new type of hydrogen optical metamaterial sensor based on the fabrication of Pd dendritic nanostructures. The fabrication of the sensor relies on a cheap self-assembly process based on the pulsed electrodeposition method in nanoporous alumina templates. By performing optical transmission measurements, we demonstrate how this sensor can monitor hydrogen gas concentrations at room temperature either by evaluating the rate of signal decay during the Pd hydrogen absorption (transient regime) or by measuring the total variation in signal once the system achieves the equilibrium state (stationary regime). We take into account the effects of the Pd-hydrogen phase transition and its size dependency to explain the kinetics of the hydrogen absorption and desorption in the studied samples. By using the transient detection method, the sensor is able to detect in approximately 50 s the explosive H-2(g) concentration threshold of 4% v/v at atmospheric pressure and room temperature.

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
INESC TEC is strongly committed to become a center of excellence in maritime technology and, in particular, deep sea technology. The STRONGMAR project aims at creating solid and productive links in the global field of marine science and technology between INESC TEC and established leading research European institutions, capable of enhancing the scientific and technological capacity of INESC TEC and linked institutions, helping raising its staff's research profile and its recognition as a European maritime research center of excellence. The STRONGMAR project seeks complementarity to the TEC4SEA research infrastructure: on the one hand, TEC4SEA promotes the establishment of a unique infrastructure of research and technological development, and on the other, the STRONGMAR project intends to develop the scientific expertise of the research team of INESC TEC.

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
Core diameter mismatch structures are proposed and experimentally investigated for curvature and vibration sensing. Two configurations are suggested, one approach uses a structure formed by splicing an uncoated short section of multimode fiber between two standard single-mode fibers (SMFs) single-mode-multimode-single-mode (SMS), combined to a fiber optical mirror at its end, and the other approach uses a structure made by splicing a section of SMF between two multimode fibers (SMSMS). In the curvature analysis, the proposed SMS sensor generates the destructive interference patterns when it is bent, varying only the attenuation of the optical signal without wavelength shifts. The SMSMS vibration sensor proved to be suitable to monitor very low frequencies such as 0.1 Hz. The configuration of the proposed sensors presents several interesting features, such as easy fabrication, low cost, high efficiency, and high sensitivity. These advantages make such sensors very useful in a wide range of applications, for instance, structural health monitoring.