It is commonly accepted today that optical fiber communications have revolutionized telecommunications. Indeed, dramatic changes have been induced in the way we interact with our relatives, friends, and colleagues: we retrieve information, we entertain and educate ourselves, we buy and sell, we organize our activities, and so on, in a long list of activities. Optical fiber systems initially allowed for a significant curb in the cost of transmission and later on they sparked the process of a major rethinking regarding some, generation-old, telecommunication concepts like the (OSI)-layer definition, the lack of cross-layer dependency, the oversegmentation and overfragmentation of telecommunications networks, and so on.

Traditionally, telecommunications are classified based on the physical properties of the channel; that is, fixed-line/wired-communications and wireless/radio communications. Following this classification, it can be safely argued that today’s core networks and metropolitan area networks (metro networks for simplicity) are almost entirely based on optical fiber systems. Moreover, the penetration of optical fiber communications in the access segment is progressing at an astonishing rate, although, quite often, it is the competition between providers, the quest for higher profits based on the established technological framework, and the legislative gridlocks that prevent an even faster adoption of this technology. Thus, a fullscale deployment of optical fiber systems in the access networks, through fixed/wireless convergence, could further reduce the role of wireless technology in transporting bandwidth over a reasonably long distance. Evidently, optical-fiber-based networks are the dominant technology, literally the backbone, of the future Internet. The fields of this technology are diverse and its engineering requires knowledge that extends from layer 1 to layer 3.

Many excellent basic text and specialized books are available today aiming to educate and/or inform scientists, engineers and technicians on the essentials in the field of optical technology. However, there is a pressing need for books presenting both comprehensive guidelines for designing fiber-optic systems and core/metro network architectures and, simultaneously, illustrating the advances in the state of the art in the respective fields. IST-NOBEL (I and II) was a large-scale research project funded from the Framework Programme 6 of the European Commission, incorporating major operators, system vendors and leading European universities. Employing a large number of experts in several fields, the project decided to collectively produce such a book as part of the disseminating activities. Thus, a considerable part of this book is based on the deliverables of IST-NOBEL with significant effort made to provide the necessary introduction of concepts and notions. The objective was to make it readable for a non-highly specialized audience, as well as to demystify the necessity behind the introduction of this or that novelty by clearly stating the underlying “need.” It is left to the readers to decide whether we have succeeded in our goals.