Abstract

Abstract
A simple splice technique to fuse a SMF-28 (TM) and a microstructured fibre using a conventional electric-are splicer is presented. The technique consists in applying the electric arc in the SMF-28 (TM) region. The fusion-loss dependence with arc duration for constant fusion power is also investigated. A splice loss of 0.25 dB is obtained with high rtproducibility. (c) 2005 Wiley Periodicals, Inc.

Abstract
A multiplexer/demultiplexer for 100GHz channel spacing based on chirped fibre Bragg gratings with different bandwidths and optical circulators is presented. The spectral characteristics, specifications and operation of these passive devices are described, showing its potential use in dense wavelength division multiplexing (DWDM) applications.

Abstract
The current status of the research and development as well as the recent contributions in optical communications at INESC Porto is reviewed. This review includes all the work carried out in the last few years in optical fiber communications, namely the development of passive and active optical devices. Some of the passive structures that have been studied and developed are: add-drop multiplexers, multiplexer/ demultiplexer based on Bragg grating technology, dispersion compensators, and optical cross-connects. Active photonic devices such as wavelength converters, fiber lasers, and fiber amplifiers have also been studied. New ideas are being continuously developed and tested.

Abstract
The electric arc technique allows the inscription of long-period gratings (LPGs) virtually in all types of fibers, including non-photosensitive fibers, the case of non-Ge doped photonic crystal fibers being of particular interest. LPGs written in standard fibers using this technique have shown a high thermal stability. Also, the resistance to. - radiation of LPGs arc-induced in pure-silica-core fibers is being assessed and the achieved results are very promising. We have also demonstrated that the combination of arc-induced LPGs and UV-induced fiber Bragg gratings (FBGs) leads to sampled FBGs that are able to address sensing functionalities with enhanced performance. Therefore, as a result of their properties, gratings induced by arc-discharges can find a wide range of applications in optical communications as well as in fiber sensing.

Abstract
A study on arc-induced long-period fibre gratings (LPFGs) revealed that their strain sensitivity depends on the electric current of the arc discharge. Based on that property, a sensor scheme comprising two concatenated LPFGs was implemented for discrimination of temperature and strain effects. This sensor presented resolutions of +/-0.1 degreesC/rootHz and +/-35 muepsilon/rootHz, respectively.