This book deals with the latest achievements in the field of ferroelectric domain engineering and characterization at micro- and nano-scale dimensions and periods. The book collects the results obtained in the last years by world scientific leaders in the field, thus providing a valid and unique overview of the state-of-the-art and also a view to future applications of those engineered and used materials in the field of photonics. The second edition covers the major aspects of ferroelectric domain engineering and combines basic research and latest updated applications such as challenging results by introducing either new as well as extended chapters on Photonics Crystals based on Lithium Niobate and Lithium Tantalate crystals; generation, visualization and controlling of THz radiation; latest achievements on Optical Parametric Oscillators for application in precise spectroscopy. Further more recent advancements in characterization by probe scanning microscopy and optical methods with device and technological orientation. A state-of-the-art report on periodically poled processes and their characterization methods are provided on different materials (LiNbO3, KTP) furnishing update research on ferroelectric crystal by extending materials research and applications.