3 - Optical fiber production techniques

Abstract

This chapter discusses the optical fiber production techniques. There are several methods of manufacturing optical fiber; all of them involve the drawing down of an optical fiber preform into a long strand of core and cladding material. This chapter reviews the optical fiber production methods developed in order to achieve the desired tolerances. As it is drawn down to produce the fiber structure the strand is stronger than steel of a similar diameter, however, the silica surface is susceptible to attack by moisture and other airborne contaminants. In order to prevent degradation, the fibers are coated during manufacture with a further layer known as the primary coating. Thus, the final product of the fiber production process is primary coated optical fiber. This element forms the basis for all other fiber and cable structures. The fundamental aim of optical fiber manufacture is to produce a controlled, concentric rod of material comprising the core and cladding. The quality of the product is determined by the dimensional stability of the core, the cladding, and also the position of the core within the cladding. The generic methods of manufacturing optical fibers include rod-in-tube, double crucible, and the progressive doping of silica-based materials.