Abstract
Permanent long-period gratings were written using arc discharges in two aluminosilicate fibers, one of which was doped with erbium. Reversible gratings were also mechanically induced in both fibers. The thermal behavior of the arc-induced gratings was investigated at up to 1100 degrees C. It was found that the shift of the resonant wavelengths exhibited a well-defined linear dependence on temperature up to 700 degrees C. (c) 2005 Optical Society of America.

Abstract
We experimentally study the effect of ionizing radiation on the properties of long-period gratings fabricated in two pure-silica-core fibers with the arc-discharge technique. It is observed that the spectra of the gratings remain almost unchanged after being subjected to doses in excess of 0.5 MGy. The results also show that the gratings' temperature and strain sensitivities are not affected by gamma radiation. (c) 2005 Optical Society of America.

Abstract
An intensity-referenced temperature-independent curvature-measurement technique that uses a smart composite that comprises two chirped fiber Bragg gratings is demonstrated. The two gratings are embedded on opposite sides of the composite laminate and act simultaneously as curvature sensors and as wavelength discriminators, enabling a temperature-independent intensity-based scheme to measure radius of curvature. Also, the system's performance is independent of arbitrary power losses that are induced in the lead fibers to the sensing head. It is demonstrated that the measurement range depends on the relative positions of the chirped fiber Bragg gratings and on their spectral bandwidths. By using two chirped fiber Bragg gratings with bandwidths W-1 = 2.8 nm and W-2 = 3.7 nm and with central wavelengths at lambda(01) = 1560.3 nm and lambda(02) - 1563.7 nm, we obtained a resolution of 1.6 mm/(1)Hz for the measurement of the radius of curvature (similar to R = 350 mm) over the measurement range 190 mm < R < infinity. (c) 2005 Optical Society of America.

Abstract
This paper presents a performance evaluation of a multiband-orthogonal frequency division multiplexing (MBOFDM) ultra-wideband (UWB) signal transmission over two types of perfluorinated graded-index polymer optical fibers (PFGI-POFs) with diameters of 62.5 µm and 120 µm, using a lowcost optical transceiver. Experimental measurements of packet error rate (PER) and minimum transmitted powers to achieve the maximum allowed PER show that it is possible to have a viable transmission at data rates of 480 Mbps, 200 Mbps and 53.3Mbps over 100, 150 and 200 meters of PF-GI-POF, respectively, preceded by a 1 meter wireless link. ©2010 IEEE.

Abstract
In this paper, we study the performance of the optimum receiver for nonlinear distorted OFDM signals in RoF applications, which is composed by a demodulator followed by an ML detector. The demodulator observes the various intermodulation products to compute a set of sufficient statistics, while the detector observes the sufficient statistics to compute an estimate of the original data. Particularly, we concentrate on the uplink of intensity modulation/direct detection RoF system where the OFDM signal suffers from linear distortion (fading), nonlinear distortion and noise. We demonstrate that the optimum receiver outperforms the conventional OFDM receiver by several orders of magnitude.

Abstract
We assess the performance of a coherent optical system employing a phase estimation algorithm combined with a least mean square decision-directed equalizer in a feedback configuration and compare it to the constant modulus algorithm with an independent carrier phase estimation approach for 16-quadratic-amplitude-modulation transmission. Both series and parallel implementations are discussed. Hardware issues regarding a recursive implementation of the estimation filter are also reported.