Nonlinear optical fluorinated polyimide/inorganic composites for optical interconnections and devices

A nonlinear optical (NLO) active alkoxysilane chromophore (SGDR1) was successfully synthesized. A fluorinated polyimide/SGDR1 composite was prepared to improve the poor temporal stability of nonlinearity at elevated temperature for the reported poled sol-gel film. The poled composite film was characterized by FTIR, DSC, TGA and UV-Vis. Results show that the composite displays good hydrophobic properties, high glass transition temperature (T_g: 266degC), and high decomposition temperature (T_d5: 433degC) although the composites were cured at lower temperature (200degC). UV results show that the lambda_max of composite film is 293.5 nm. The composites film also exhibits a high contact angle of 90.04deg, a low surface energy of 18.17 mN/m, and a low water absorption of 0.082%. The second harmonic coefficient d₃₃ of the composite was measured to be 18.39 pm/V by using maker fringe technique. The new NLO composite exhibits 85% of the original d₃₃ over 720 hr at 100degC and possesses much better stability than the reported sol-gel film. It is found that the silicon crosslinked network can significantly improve the properties of the composites and the fluorine and fluorine position in the chromophore side chain of PI can significantly affect properties of composites.