Abstract
In this article, we present detailed results on the fabrication and characterization of mechanically induced gratings produced by winding a string around a fiber/tube set. A comparison between the mechanical and arc-induced gratings is made, which allowed its to draw some conclusions on the formation mechanisms of the latter. The usefulness of mechanical gratings in research labs is discussed and two typical applications are. also presented. (C) 2008 Wiley Periodicals, Inc.

Abstract
A novel analytical Gaussian approximation is developed for the evaluation of the distortion spectrum introduced by a nonlinear amplifier. This method allows to consider high-order distortion contributions when the device is driven by a broadband signal with Gaussian amplitude distribution. The results are applied to a ninth-order power series model based on well known single-tone and two-tone analysis parameters. The cascade of two or more amplifiers is investigated as well providing a complete set of tools for the early system specification of broadband transceivers. Simulations shows excellent agreement even for high input power levels, when former third-order and fifth-order approximations fail to yield accurate predictions. © 2008 IEEE.

Abstract

Abstract
The formation mechanisms and properties of arc-induced gratings are intrinsically related to the temperature attained by the fiber during arc exposure. In this work, we present further results oil the estimation of the fiber temperature based oil the use of electrically insulated thermocouples. Computer simulations show that under typical arc discharge conditions, the fiber reaches steady-state thermal equilibrium in less than half a second, having a peak temperature of about 1350 degrees C (C) 2008 Wiley Periodicals, Inc.

Abstract
A Simulink blockset for the fast evaluation of the non linear distortion caused by RF amplifiers, mixers and BaseBand amplifiers in broadband transmission systems such as the orthogonal frequency division multiplexing (OFDM) adopted in the WLAN or more recently in the UWB standard is presented. Each amplifier block within the tool is described by a ninth-order power series extracted from classical one-tone and two-tones parameters. The distortion description is directly deduced from the spectral analysis of the system, thus avoiding the need for time consuming, time domain simulations and providing a powerful tool for the fast evaluation of the design requirements. A Gaussian approximation is adopted to simplify calculations for high order distortion terms spectra. The blocks within the tool can be cascaded providing analytical predictions for the chain of two or more amplifiers as well. A simulation comparison to a time domain simulator proves that the model keeps reliable up to very high input power levels, outperforming former third-order and fifth-order power series approximations in the literature. ©2008 IEEE.

Abstract