Reliability Study of Optical Adhesive For Photonic Devices Under The High Temperature And High Humid Environment

The two critical parameters (film thickness and the refractive index) of waveguide structure are studied under different environmental condition, such as high temperature and high humidity to understand the reliability issues of the epoxy- based optical polymer. The thickness of the spin coated epoxy- based polymer film is decreased due to exposure at high temperature and increased due to exposure in high humidity. The refractive index of such epoxy-based polymer is found decreased at the high temperature for a certain time due to the evaporation of solvents & decomposition at that high temperature, but again increased after exposing for long time due to the chemical modification & oxidation of the epoxy- based polymer. Refractive index of the epoxy-based polymer was found to decrease with moisture absorption due to the decrease in the density. Birefringence is also increased with exposed time as the rate of change of the refractive indices for T_E and T_M mode is not similar due to stress generation in the film. This study provides the important conclusions for the fabrication of better performance and reliable polymer photonic devices.