How are fiber optic made?

The actual process varies significantly from one manufacturer to other. In essence, a huge cylinder of core is made off high purity material, an element termed as preform. It is later heated or treated and drawn in a filament that is then coated along with the external layer with a diverse refractive index.

Other systems contain co-extrusion, direct co-polymerization, continuous casting, injection, soft extrusion and wet drawing with mercury formers.

These later ways, and others under research, try to get a better alignment of polymer chains in order to enhance transmission and decrease attenuation. Actually, the fiber stretching and tensioning after drawing to encourage molecular alignment is one of the industry secrets.