This book offers a much-needed practical guide to characterizing difficulties met by designers of electro-optical current devices, such as lasers, laser diodes and photodiodes, and advanced optical devices, such as avalanche and erbium diodes, to overcome drawbacks associated with optical communication links, wireless (for LIDAR applications) and wired (for fiber-optical communication). All these drawbacks suffer from various types of noises inside each element of the devices under analysis and the corresponding fading phenomenon when various types of optical signals with information data transverse these channels.It will appeal to undergraduate and postgraduate students and professionals dealing with optical communication and the design of electro-optic devices. The book explores the theoretical background and practical aspects both when optical signals propagate through a wireless channel (for LIDAR atmospheric applications) and when they propagate through an optical fiber.