Fabrication of optical fiber

The drawing of optical fibers from silica preforms has, over a short period of time, progressed from the laboratory to become a manufacturing process capable of producing millions of kilometers of telecommunications fiber a year. Modern optical fiber fabrication processes produce low-cost fiber of excellent quality, with transmission losses close to their intrinsic loss limit. Today, fiber with transmission losses of 0.2 dB per kilometer of fiber are routinely drawn through a two-stage process that has been refined since the 1970s. In the second stage, the rod, or preform as it is known, is heated to its softening temperature and stretched to diameters of the order of 125 microns. Tens to hundreds of kilometers of fiber are produced from a single preform, which is drawn continuously, with minimal diameter fluctuations. During the drawing process one or more protective coatings are applied, yielding long lengths of strong, low-loss fiber, ready for immediate application