Transient Heating of PMMA Preforms for Microstructured Optical Fibers

A uniform transverse temperature profile is crucial for the direct draw of microstructured optical fibers (MOFs). This can be difficult to achieve for preforms made from materials of poor thermal conductivity, such as polymer. In this paper, we have investigated the transient heating process for drawing MOFs from preforms made from polymethylmethacrylate. Numerical results show that inclusion of radiative transfer across the hole structure is essential for accurately predicting transient heating, and the heating time required decreases strongly with air fraction, but the transverse temperature difference increases with the ratio of the heating temperature to the material glass transition temperature. Thus, we deduced that a strategy for efficient and uniform heating is to use a high-temperature preheating section with a subsequent lower temperature drawing section