The Manufacturing Process of Optical Fiber

   Both the core and the cladding of an optical fiber are made of highly purified silica glass. An optical fiber is manufactured from silicon dioxide by either of two methods. The first, the crucible method, in which powdered silica is melted, produces fatter, multimode fibers suitable for short-distance transmission of many light wave signals. The second, the vapor deposition process, creates a solid cylinder of core and cladding material that is then heated and drawn into a thinner, single-mode fiber for long-distance communication.

   There are three types of vapor deposition techniques: Outer Vapor Phase Deposition, Vapor Phase Axial Deposition, and Modified Chemical Vapor Deposition (MCVD). This section will focus on the MCVD process, the most common manufacturing technique now in use. MCVD yields a low-loss fiber well-suited for long-distance cables.