Core-suction technique improves preform quality

Researchers at Virginia Polytechnic Institute and State University (Blacksburg, VA) and Fisk University (Nashville, TN) have developed a simple core-suction technique for the fabrication of high-quality optical-fiber preforms made with highly nonlinear glasses as the core material. The researchers used the technique to successfully fabricate preforms with Schott SF6 and lead tellurium germanate glass cores, and drew these into fibers.

A variant of the crucible technique, in which the core glass (as a powder or a thin rod) is melted as the fiber is drawn, the core-suction technique uses a vacuum to draw molten core material melted in a conventional furnace up into a cladding tube. The elimination of multiple processing steps required for rod-in-tube or crucible techniques reduces contamination of the core glass and eliminates air bubbles, resulting in higher-quality preforms. Purity of the core glass can be furthered by using a high-purity silica tube as the inner wall of the furnace, allowing the flow of inert gas to create a controlled atmosphere during preform fabrication. Contact Nitin K. Goel at [email protected].