To transmit light effectively, fiber optic cable must contain glass of the highest purity. The process of making glass with this level of purity is very demanding, requiring careful control over the materials and processes involved.
Create the Fiber Optic Preform A preform is a cylindrical glass blank that provides the source material from which the glass fiber will be drawn in a single, continuous strand. Creating the preform takes several hours, after which additional time is required for the glass blank to cool. Once cooled, the glass is tested to ensure that it meets quality standards, especially in terms of index of refraction.
Draw Optical Fiber from the Preform In this step, the finished glass preform is installed at the top of a tower which supports various devices used in the fiber drawing process. The process begins by lowering one end of the preform into an in-line furnace that produces heat in a range of 3,400 to 4,000 degrees Fahrenheit. As the lower end of the preform begins to melt, it forms a molten glob that is pulled downward by gravity. Trailing behind the glob is a thin strand of glass that cools and solidifies quickly. At the end of the run, the completed fiber is wound onto a spool.
Step # 3
Test the Fiber Optics. The completed optical fiber must undergo a number of tests to determine the quality of the finished product. The following are a few of the assessments involved:
• Refractive index profile
• Fiber geometry inspection, including core, cladding and coating
• Tensile strength
• Bandwidth capacity
• Attenuation at different wavelengths
• Chromatic dispersion