Abstract: A liquid phase epitaxial growth technique for growing lithium niobate films on lithium tantalate substrates involves growth from a flux system based on either lithium borate, lithium tungstate, tungsten oxide or potassium tungstate. Optical waveguiding occurs in films grown from the described flux systems.

Abstract: The comprehensive large scale integration of thin-film optical circuits is made possible by a series of related developments. The key concept is the isolation of the high index substrate, necessary to active devices, wherever it is desired to have a passive device, by the interposition of an oxide layer such as SiO.sub.2. It is preferred that the passive devices and the SiO.sub.2 by amorphous. This new arrangement allows the use of discrete thin-film corner reflectors, instead of distributed feedback, in resonant active devices and wherever a reflector or beam-splitter is needed. Further, the active devices may be located photolithographically by etching windows in the SiO.sub.2 layer. All of the active devices share a common active layer, which forms the passive devices wherever it extends between windows and simultaneously is the light guiding layer throughout.