Control of stress distribution during large radius fiber optic taper drawing process based on 2D simulation

This paper presents numerical investigation of stress distribution within fiber optic taper during its drawing process. A thermoviscoelastic model is proposed to describe the glass mechanical behavior from solid to liquid in a broad temperature range where the fiber optic taper drawing undergoes. The model is validated by experiments and used to study stress distribution in the fiber optic taper during fabrication. Roles of key parameters are discussed including geometrical configuration of the furnace, temperature difference between heating and cooling regions and drawing speed. Results show that the stress distribution is mainly influenced by thermal environment surrounding the taper. While the afore-mentioned key parameters all affect the thermal environment, they thus also change the stress distribution in the fiber optic taper. A shorter length of adiabatic region and smaller temperature difference between the heating region and cooling region make the impact of cooling region on thermal environment to fiber drawing more significantly. Conversely, a longer adiabatic region and a larger temperature difference will enhance the impact of heating region. Proper increase in drawing speed can promote heat transfer arising from rheologic motion, thus improving the homogeneity of stress distribution in the fiber taper. Based on the understanding derived from this study, an improved heating and drawing design is proposed to achieve more homogeneity of stress in fiber optic taper during the drawing process.