This book provides a comprehensive description of an optical communications technology known as free space optical—a next-generation communications network that uses optical signals through the atmosphere instead of fiber, RF, or microwaves. This technology potentially offers more complex ultrabandwidth communication services simultaneously to multiple users and in a very short time, compared to fiber optic technology. This text presents established and new advancements drawn from the latest research and development in components, networking, operation, and practices. This book describes the FSO network concepts in simple language. It provides comprehensive coverage in an easy-to-understand, progressive style that starts from the physics of the atmosphere and how it affects optical communications; continues with the design of a network node; and concludes with fiberless network applications from point-to-point to mesh topology. Important areas discussed include: Propagation of light in the atmosphere and phenomena that affect light propagation FSO transceiver design Point-to-point FSO systems Ring FSO systems Mesh-FSO systems and integrating the Mesh-FSO with the public network WDM Mesh-FSO FSO network security FSO-specific applications To meet the needs of both academia and industry, key mathematical formulas are presented along with descriptions, while extensive mathematical analyses are minimized or avoided. Free Space Optical Networks for Ultra-Broad Band Services serves as an ideal text for network communication professionals who enter the free space optical communication field, graduate students majoring in optical communications, optical communication engineers, researchers, managers, and consultants.