The goal of this book is to provide readers a complete understanding of optical communication streams operating at high speeds. For high-speed communications systems, optical devices and other sophisticated signal processing features have also been extensively studied recently. Typical optical devices are light emitting diodes and photodetectors. Advances in dense optical communication systems have significant applications in networking, data processing, and telecommunications. It consists of three parts: a transmitter that transforms a message into an optical signal, a receiver that transforms the optical signal back into the original message, and a channel that guides the optical signal to the desired destination. The target audience for this book also includes research, development, and design engineers from teams in the manufacturing, academic, and telecommunications industries.