Multi-cylinder apparatus for making optical fibers, process and product

Abstract

A vertically disposed apparatus used to make core-clad optical fibers inces an inner elongated cylinder removably closed at the top and provided at the bottom with an inner exit port of a smaller diameter than the inner cylinder and an outer cylinder, disposed around the inner cylinder, removably closed at the top and provided at the bottom with an outer exit port of a smaller diameter than the outer cylinder. The inner exit port is of a smaller diameter than the outer exit port and is disposed directly above the outer exit port. The apparatus also includes a heater for heating the inner and outer cylinders and acces to the inner and the outer cylinders for individually pressurizing inner and outer cylinders. The process by which the core-clad optical fibers are made includes the steps of placing a solid glass core rod into the inner cylinder of the apparatus described above, placing a solid glass cladding tube into the outer cylinder, melting the core rod and the cladding tube, quickly cooling the molten core rod and cladding tube to the drawing temperature, individually pressurizing the molten core rod and cladding tube, and drawing the core-clad optical fiber through the exit ports.