This book explores the extension of fiber optic communications technology to space optical communications. It presents the specific demands for space communications and examines propagation in a vacuum and also over the turbulence of air-free space. Space Photonic Communications begins with historical aspects of optical communications in both terrestrial and inter-satellite constellations. It presents the advances in optical communications and integrated photonics that have enabled the technological developments for space photonic communications, especially coherent optical communications to transport Tbps information. The author discusses how the transmission of massive amounts of data over very long distances requires Tera-bps communications in real time for both military and civil applications. The author also explores laser communications with the physics of laser propagation over ultra-long distances without optical amplifications at intermediate locations. He also examines modulation and receiving techniques for space photonic communications. Intended for communications engineers and professionals, especially those in laser communication technologies, this book could also be used in courses on advanced optical communications, photonic communications, and communication techniques and technologies.