The present study investigates the mass and heat transfer in the optical fibre fabrication process where a specialty optical preform with a non-homogeneous cross-sectional structure is drawn into a fibre. A finite element method was used to model the steady state fibre drawing process. The model included free surface calculation of the neck-down shape of the preform coupled with a two-dimensional heat transfer equation. The enclosure model was used for the radiation heat transfer. In addition to the silica preform the model took into account the graphite-resistance furnace structure and the inert gas surrounding the preform. Fibre designs with axisymmetric cross-sections with radial variations in material properties were modeled, including air silica structures. The effect of internal air structures was found to have a significant impact on temperature distribution. The effects of drawing parameters such as draw speed, preform diameter, draw temperature and furnace structure were also studied.
Asymptotic solutions of glass temperature profiles during steady optical fibre drawing
