Method for making core holes in cast optical fiber preforms

摘要

A method of making core holes in cast cladding glass for fabricating optical fiber preforms to make single and multimode optical fibers. Liquid cladding glass is poured into a casting mold having a metallic wire (e.g. Pt wire) that is translated through the liquid glass as it cools so that the wire essentially carves out a smooth cylindrical core hole along the cylindrical axis of the cooled cladding glass. The method substantially reduces surface contamination at the interface of the core hole and the cladding glass because any liquid glass that comes in contact with the metallic wire is removed during the process, leaving behind a pristine glass surface. The glass may be heavy metal fluoride glass, such as ZBLAN.