Method of making optical waveguide devices using perchloryl fluoride to make soot
US6109065A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 24, 1998 |
| Grant date | Aug 29, 2000 |
| Priority date | — |
| Expiry date | Apr 24, 2018 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC03B2201/40
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
Applicants have determined that much of the nonuniformity in solution doped preforms is due to nonuniformity of the soot layer caused by the high temperature necessary for complete reaction, and that MCVD fabrication using reaction temperature lowering gases such as nitrous oxide (N.sub.2 O) can produce more uniform soot layers. The conventional oxygen/reactant gas mixture presents a very small temperature window in which a uniform silica soot layer can be deposited without sintering. If the temperature in oxygen is too low, SiCl.sub.4 will not react completely and silicon oxychlorides will form. This degrades the soot layer and makes it unusable. If the temperature is too high the soot layer begins to sinter, decreasing the surface area and porosity. Adding a reaction temperature lowering gas lowers the reaction temperature and enables deposition of soot on the tube wall at a temperature substantially lower than the sintering temperature. This results in a more uniform, porous soot layer along the length of the preform and from one preform to another; and, in turn, the greater uniformity permits more uniform solution doping.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.