148 Copyright © 2013, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. Chapter 8 1. INTRODUCTION Fiber optic communication is the key element of the information era. The revolutionarily growth of telecommunication industry during the few recent decades are completely indebted to fiber optic communication. One of the fundamental elements of fiber optic communication, beside the optical fiber, transmitter, and receiver, is the opti- cal amplifier. Most important optical amplifiers are optical fiber amplifiers that use optical fibers as the gain media. Erbium-doped fiber amplifier Alireza Mowla K.N. Toosi University of Technology, Iran Nosrat Granpayeh K.N. Toosi University of Technology, Iran Azadeh Rastegari Hormozi K.N. Toosi University of Technology, Iran Optimum Design of Hybrid EDFA/FRA by Particle Swarm Optimization ABSTRACT In this chapter, the authors introduce the hybrid erbium-doped fber amplifer (EDFA)/fber Raman amplifer (FRA) and its optimization procedure by particle swarm optimization (PSO). EDFAs, FRAs, and their combinations, which have the advantages of both, are the most important optical fber am- plifers that overcome the signal power attenuations in the long-haul communication. After choosing a proper confguration for a hybrid EDFA/FRA, users have to choose its numerous parameters such as the lengths, pump powers, number and wavelengths of pumps, number of signal channels and their wavelengths, the signal input powers, the kind of the fbers and their characteristics such as the radius of the core, numerical apertures, and the density of Er 3+ ions in the EDFA. As can be seen, there are many parameters that need to be chosen properly. Here, effcient heuristic optimization method of PSO is used to solve this problem. DOI: 10.4018/978-1-4666-2666-9.ch008