Methods of production of optical fibers

In double-crucible method, two pure glass rods differing in refractive indices are used as core and cladding. The base material used here is soda borosilicate. A mixture of silicon tetrachloride and titanium tetrachloride is used in inside-vapour-phase oxidation method. This method is also known as inside-vapour-deposition method where the tetrachloride mixture (of silicon and titanium) is allowed to react with oxygen in an open flame. This process is called flame hydrolysis. This method is not suitable for multimode operation. Hence researchers prefer outside-vapour-deposition method where a low density porous glass is fed through a oxyhydrogen burner. This burner consists of three concentric orifices. Middle one is used for halide vapours. Outer one for feeding the fuel and gas mixtures. The third one is used for shielding gas to avoid premature reaction of the halides. Some other methods for the production of optical fibers are chemical vapour deposition method, its modified version, plasma enhanced version, plasma activated version, plasma outside deposition method and vapour phase axial deposition method.