Abstract
This paper describes the development of a novel microfluidic platform for multifactorial analysis integrating four label-free detection methods: electrical impedance, refractometry, optical absorption and fluorescence. We present the rationale for the design and the details of the microfabrication of this multifactorial hybrid microfluidic chip. The structure of the platform consists of a three-dimensionally patterned polydimethylsiloxane top part attached to a bottom SU-8 epoxy-based negative photoresist part, where microelectrodes and optical fibers are incorporated to enable impedance and optical analysis. As a proof of concept, the chip functions have been tested and explored, enabling a diversity of applications: (i) impedance-based identification of the size of micro beads, as well as counting and distinguishing of erythrocytes by their volume or membrane properties; (ii) simultaneous determination of the refractive index and optical absorption properties of solutions; and (iii) fluorescence-based bead counting.

Abstract
A long-period grating (LPG) written on a standard single mode fiber is investigated as a curvature and vibration sensor. It is demonstrated a high sensitivity to applied curvature and the possibility to monitor vibration in a wide range of frequencies from 30 Hz to 2000 Hz. The system was tested using an intensity based interrogation scheme with the LPG sensor operating in the curvature regime. Results have shown a reproducible frequency discrimination in the 30 Hz to 2000 Hz, with resolutions between 11 mHz and 913 mHz. Frequency retrieval could be perfouned independent of temperature up to 86 degrees C.

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
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.