This review volume presents new developments in the preparation, physical characterization and applications of insulating materials for Optoelectronics. Insulators occupy a leading position as laser and optical amplifier hosts, electrooptic and acoustooptic modulators, frequency doublers and optical parametric oscillators, photorefractive devices and radiator detectors. These applications rely heavily on the development of advanced techniques for the preparation of both bulk and waveguide structures, the adequate knowledge of the microscopic behaviour defects, impurities and a thorough understanding of their response to electromagnetic fields. All these topics relating basic physicochemical aspects and applied performance are authoritatively discussed in the book.