All-polymer multimaterial optical fiber fabrication for high temperature applications

In this work, we report the fabrication of an all-polymer multimaterial optical fiber based on two different grades of cyclo-olefin polymers (known as Zeonex) and the high-performance thermoplastic polysulfone (PSU) with glass transition temperature (Tg) of 189°C. The core/cladding structure using the Zeonex polymers (E48R/480R, respectively) was developed using a co-extrusion method followed by a rod-in-tube approach to form the final preform. The fiber materials were characterized in terms of their Tg, viscosity as well as refractive index profiles. The final preform was thermally drawn down to a fiber with ∼300 µm and ∼70 µm total and core diameter, respectively. We thermally characterized and compared our step-index fiber with a commercially available polymer (Cytop) as well as a purely Zeonex single-mode step-index fiber. The proposed multimaterial fiber exhibited stable operation at temperatures as high as 180°C being ∼35°C higher than any polymer fiber reported so far to the best of our knowledge. Therefore, we believe that our results constitute a significant step forward for the polymer optical fiber community making the proposed polymer multimaterial fiber an efficient route towards truly heat-resistant applications.