Abstract
This Letter reports on the assembly on the tip of an optical fibre of a metamaterial film fabricated by a self-assembly bottom-up method, composed of silver nanowires embedded in an alumina matrix. By illuminating the film through the fibre in a reflection configuration, we observe experimentally the optical response of the metamaterial in agreement with theoretical predictions and interpreted as the excitation of surface plasmon-polaritons in the cylindrical surface of the nanowires. These results pave the way for low-cost optical fibre devices that incorporate metamaterial films. (c) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Abstract
Focused ion beam (FIB) patterning of 3D topography on optical fiber tips for application in stand-alone, rugged and simplified setups for optical tweezers cell sorters, optical near-field lithography and optical beam profile engineering are reported. We demonstrate various configurations based on single-step FIB patterning, multiple-step FIB processing and hybrid approaches based on optical fiber pre- and post-FIB treatment with either etching, fusion splicing, photo-polymerization or electroplating steps for optical fiber texture, topography and composition engineering. Different conductive coatings for minimal charge accumulation and beam drift are studied with the relative merits compared. Furthermore optimal beam parameters for accurate pattern replication and positioning are also presented. Measured experimental field profiles are compared with numerical simulations of fabricated optical fiber tips for fabrication accuracy evaluation. Applications employing these engineered fiber tips in the field of optical tweezers, optical vortex generation, photolithography, photo-polymerization and beam forming are presented.

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
A study of long period fiber gratings (LPFG) over coated with iron (Fe) and subjected to oxidation in water with different sodium chloride (NaCl) concentrations is presented. The formation of iron oxides and hydroxides was monitored in real time by following the features of the LPFG attenuation band. Preliminary results show that Fe coated LPFGs can be used as sensors for early warning of corrosion in offshore and in coastal projects where metal structures made of iron alloys are in contact with sea or brackish water.

Abstract
This paper investigates numerically the performance of a design for an optical sensor of the refractive index of gases and liquids based on smart or functional metamaterial films (smart optical metamembranes).