Synchronous Measurement of Optical Transmission and Viscoelastic Properties of Polymer Optical Fibers

In this paper, synchronous mechanical and optical measurements are proposed using the dual cantilever mode of dynamic mechanical analysis (DMA). It was demonstrated that this mode enables the detection of phase transitions in both the core and cladding materials of polymer optical fibers (POFs), with corresponding changes in optical signal intensity observed across different light wavelengths. In dual cantilever mode DMA, an increase in optical transmission was recorded between the two detected glass transition temperatures. The initial increase in transmission is attributed to cladding softening and the consequent reduction in internal stresses in the POF, while the maximum in optical transmission coincides with the beginning of the phase transition in the core material. To compare and interpret the optical and thermo-mechanical results, Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) measurements were carried out on POF pieces, as well as separately on the core and cladding materials. This integrated technique yields quantitative data on a material’s viscoelasticity and light-transmission changes, making it valuable for quality control and for predicting the long-term behavior of advanced POFs in various applications.