Integrated quantum optics is an emerging research field that offers scalable approaches towardsexciting new applications such as quantum simulation. The basis for all integrated quantumoptics applications is, obviously, the integrated devices, which must exhibit supreme samplequality and replicability.In this thesis, we developed and established a novel technology for the fabrication of tailored,periodically poled waveguides in potassium titanyl phosphate (KTP), a material that is of highinterest due to its unique dispersion properties and, at the same time, exquisitely challengingfor fabrication. We conducted detailed studies of the properties of KTP, which led to a betterunderstanding of the material behaviour during the manufacturing. These results allowed us tofuse electric field-enhanced domain inversion and potassium-rubidium-exchanged waveguidesto enable the production of periodically poled KTP waveguides.We further established a coating technology, which facilitates the deposition of engineered dielectriccoatings on waveguide end facets and other substrates. The coatings are based onoxygen ion assisted electron beam evaporation and integrated broadband monitoring, and wedemonstrate tailored, multifunctional coatings.We used the new technologies to realise two new devices for frequency conversion between UVand visible wavelengths: periodically poled KTP ridge and channel waveguides. Both deviceswere thoroughly characterised, and we demonstrated both second harmonic generation and parametricdown-conversion with high efficiencies. The results of our thesis will help to advancethe field of integrated quantum optics by providing important progress in the technology, whichlies at the heart of all applications.