Abstract
The intensity profile of a focused beam of light can exert small drift forces on particles with a few microns and even smaller, which can be used to confine or manipulate them. Optical trapping has several applications, in particular it has been adopted as a powerful tool in biology, allowing, for instance to manipulate in vivo single cells. A wide variety of optical setups have been implemented to optically trap microscopic bodies, however, the single beam trap using a tightly focused Gaussian beam continues to be the most used. Recent developments introduced an alternative to bulk optical trapping systems based on lensed optical fibers. This work presents simulations showing new designs of fiber optic and 2D waveguide tweezers based on studies of the forces acting on dielectric particles immersed in media with a distinct refractive index, which take into account the refractive index and structure of the particles.

Abstract
This paper presents a study of optical forces acting on dielectric particles in media of distinct refractive index. The radiation pressure forces produced by optical tweezers are calculated using the finite difference time domain method as well as the Lorentz force on electric dipoles. The model considers a 2-dimension structure composed of a waveguide and a dielectric microparticle. Furthermore, the paper presents preliminary experimental results concerning the implementation of fiber optical tweezers system based on polymeric lensed fibers.

Abstract
In this work, we address a study of the spectral reflectance of silver nanowire metamaterials in the visible and near-infrared regions. To this end, several samples were fabricated with different fill-ratios and lattice constants, and their respective optical responses characterized in terms of these parameters. We perform a direct comparison between the collected experimental data with the values predicted by different analytical homogenization models to provide a better understanding of the effective optical behavior of this kind of metamaterials.

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
In this paper a spun elliptically birefringent photonic crystal fiber is fabricated and characterized. Its performance as a current sensor, using a polarimetric configuration, was tested and compared against single mode fiber at 633 nm. In particular the sensor sensitivity and linearity was investigated using fiber loops with different radius or number of turns around the conductor. The results obtained show that the spun fiber (40 rotation per meter) is able to suppress quite effectively the effects of the bend induced birefringence as compared to the standard fiber.

Abstract
A fiber optic sensor for high sensitivity refractive index and temperature measurement able to withstand temperature up to 450 degrees C is reported. Two identical LPG gratings were fabricated, whereas one was coated with a high refractive index (similar to 1.78) sol-gel thin film in order to increase its sensitivity to the external refractive index. The two sensors were characterized and compared in refractive index and temperature. Sensitivities of 1063 nm/RIU (1.338 - 1.348) and 260 pm/degrees C were achieved for refractive index and temperature, respectively.