Method for eliminating Li.sub.2 O out-diffusion in LiNbO.sub.3 and LiTaO.sub.3 waveguide structures
US4196963A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 30, 1978 |
| Grant date | Apr 8, 1980 |
| Priority date | — |
| Expiry date | May 30, 1998 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2004/80
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A process for suppressing the out-diffusion of Li.sub.2 O from LiNbO.sub.3 and LiTaO.sub.3 waveguide structures by exposing the structures to a Li.sub.2 O-rich environment at sufficient vapor pressure that Li.sub.2 O diffuses into the structure as a compensation process and a solid-solid surface interaction occurs. In one embodiment of the invention, the out-diffusion of Li.sub.2 O from LiNbO.sub.3 and LiTaO.sub.3 crystals into which Ti has been diffused is eliminated by annealing the structure in a high purity powder of LiNbO.sub.3 or LiTaO.sub.3. In a second embodiment, the Li.sub.2 O out-diffusion is partially suppressed by annealing the structure in molten LiNO.sub.3. In a third embodiment of the invention, a waveguide structure comprising a Li.sub.2 O-rich guiding layer is formed by annealing LiNbO.sub.3 or LiTaO.sub.3 crystals in a high purity powder of LiNbO.sub.3 or LiTaO.sub.3, which not only suppresses Li.sub.2 O out-diffusion but also promotes Li.sub.2 O in-diffusion into the crystals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.