Optimized design of temperature-insensitive optical waveguide coupler with 120-nm bandwidth using fluorinated polyimide

Method for designing optimized temperature-insensitive optical waveguide couplers by use of fluorinated polyimide is presented. Based on measured temperature and dispersion characteristics of fluorinated polyimide, a 3-dB waveguide coupler with a 120-nm bandwidth with minimal temperature variance is designed and verified through simulation based on three-dimensional beam propagation. The coupling ratio of the theoretical device is 50 +/- 0.7% in the waveband 1490 to approximately 1610 nm and the temperature range -10 to approximately 40 degrees C.