Chapter 4 - EDFAs, Raman Amplifiers and Hybrid Raman/EDFAs

Abstract

The advent of the erbium-doped fiber amplifier on the eve of the 1990s made high-capacity wavelength division multiplexed systems possible, allowing service providers to meet the exploding demand generated by the growth of the telecommunications industry and of the internet. This chapter reviews the basic properties of optical amplifiers of importance for the original dense wavelength division multiplexing (DWDM) applications of optical amplifiers, such as gain, output power, and noise performance, and discusses recent developments related to advances in wavelength division multiplexing (WDM) networks, such as the reconfigurable optical add/drop multiplexer (ROADM)-based wavelength-routed systems and the WDM systems with channel rates of 100 Gb/s or more. For the ROADM-based networks, where channels follow diverse paths and are dynamically reconfigured, interactions between channels must be understood and managed. Properties of EDFAs such as their transient response and their spectral response are major sources of such interactions and are of increased importance for such networks. This chapter also discusses recent advances in modeling the inhomogeneous behavior of erbiumdoped fiber amplifier (EDFAs), particularly spectral hole burning (SHB) and dynamic response in EDFAs, essential for the design of ROADM-based networks and EDFAs for ROADM-based networks. For high-capacity systems, amplifier properties such as the noise performance are of increased importance. it describes the distributed Raman amplifiers and hybrid Raman/EDFA amplifiers, which can significantly improve noise performance compared with discrete EDFAs.