Erbium-doped and Raman fiber amplifiers

This paper provides keys to understand why erbium-doped fiber amplifiers (EDFA) have revolutionized signal transmission techniques and how they can complement with Raman amplification in the next generation of telecommunications systems. The basic physics of EDFAs is first reviewed, followed by a description of requirements for both terrestrial and submarine system applications. The related characteristics and second-order effects causing limitations in such systems are then discussed. Finally, future developments based on operation in the 'long-wavelength band' and the benefits of using distributed Raman amplification are analyzed. (C) 2003 Academie des sciences/Editions scientifiques et medicales Elsevier SAS. All rights reserved.