Photorefractive waveguides

In integrated optics, optical waveguides are fundamental elements for the development of integrated devices, including light sources, modulators, detectors, optical pathways, receivers and switches. For the fabrication of optical integrated waveguide components, grating couplers or other complex integrated structures realized on planar optical waveguides, materials with high photorefractivity are surely of great interest since they allow applying photorefractive direct-laser-writing techniques which are of lower cost and less time-consuming than conventional photolithography and etching processes. This chapter provides an overview of classes of photorefractive materials such as photorefractive glasses, glass-ceramics, crystals and polymers, which are promising candidates for integrated optics. Different aspects, including material preparation, photorefractivity investigation and the fabrication of photorefractive direct-laser-written micro/nano-optical structures such as channel waveguides and gratings in each type of photorefractive materials, are also discussed.