Thermal behavior of optical fibers during the cooling stage of the drawing process

A general method that predicts the thermal behavior of optical fibers during the cooling stage of the drawing process was developed. The method can be used for thin diameter D < 200 μm, medium (200 μm < D < 500 μm), and thick (0.5 mm < D < 2 mm) single as well as core-clad fibers. A two-dimensional analysis implementing a finite difference method combined with the Kármán–Pohlhausen technique was performed to obtain the temperature profiles in thick fibers. This method accounted for axial and radial heat conduction, and can also be applied to thin and medium fibers. The case of the core-clad fibers was investigated to obtain the temperature profiles both in the radial and the axial directions. All results are presented in graphical form and can be used for optimization of the drawing process.