Book excerpt: The book focuses on photonic devices and systems for space applications and critically reviews the most promising research advances in the field of photonic technologies, which may have a significant impact on the performance of space systems.Photonics is emerging as a crucial enabling technology having the potential of enhancing many space systems, including the links for on-board data handling, the high-resolution measurement systems, and the processing units. The book discusses this subject with a special emphasis on the new guided-wave devices with high performance, low cost and size.Most of the scientific content of the book is novel and it is devoted to academic and industrial researchers working on the field.