DEVICE AND METHOD FOR DRAWING OPTICAL WAVEGUIDE FIBER

摘要

A method and apparatus for drawing an optical waveguide fiber which minimizes fiber bow caused by differential stresses in the cladding layer of the fiber are disclosed. The fiber is drawn from a preform (10) which is heated in a draw furnace (12). Gases introduced at the top of the furnace form a boundary layer adjacent to the fiber which passes through the furnace, along with the fiber, into a tube. The tube isolates the fiber from the ambient atmosphere so that the boundary layer of gases established in the furnace remains substantially uniform until the viscosity of the cladding layer of the fiber is high enough to minimize differential stresses around the circumference of the fiber.