"Optical communication, also known as optical telecommunication, is communication at a distance using light to carry information. It can be performed visually or by using electronic devices. Optical communications systems are very important for all types of telecommunications and networks. They consist of a transmitter that encodes a message into an optical signal, a channel that carries the signal to its destination, and a receiver that reproduces the message from the received optical signal. Indeed, the worldwide telephone network, the worlds largest communications system, is fiber optic-based. Further, optics is finding progressively more communications applications by the day, not to speak of the numerous sensing applications that are presently being implemented. In some areas, optics is being implemented somewhat more slowly than originally predicted. This is in great part due to cost. In the telephone network, hardware cost was really not an issue compared to a myriad of other costs such as right of way and cable installation, and the initial implementations were carried rapidly rather than costeffectively. The telecommunications solutions, which were the first to be carried out, could therefore not be taken over directly into other applications. Now, though, the telecommunications market is competitive as are the data communications market and others, and various new cost-effective solutions are appearing. There are numerous applications where optics is competing. Optical Communications Systems cover general concepts of optical and wireless optical communication systems, optical amplifiers and networks, optical multiplexing and demultiplexing for optical communication systems, and network traffic engineering. This book is intended to research, development and design engineers from the teams in manufacturing industry; academia and telecommunications service operators/ providers."