1.2 Optical amplifiers: recent developments 3 the amplifiers and these emerging trends. Experts on the amplifiers, on the network equipment in which they are used, and on the service provider networks in which the equipment is deployed were asked to examine how the emerging network trends drive amplifier requirements, how amplifier characteristics guide or constrain the design and operation of networks with more complex optical connectivity and higher capacities, and how, as a result, the engineering of solutions to various network design and operation challenges increasingly require network-wide anal- ysis and network-wide solutions. Application spaces ranging from low-cost, short- reach access networks to terrestrial networks to ultra-long-haul transcontinental undersea systems are considered. In the remainder of this chapter, the recent trends in optical amplifiers that are driven in large part by emerging trends in network applications are discussed, then summaries of the remaining chapters are provided. 1.2 OPTICAL AMPLIFIERS: RECENT DEVELOPMENTS Four major trends characterize developments in the amplifiers over the past decade. These include the increase in amplifier bandwidth to support larger