The nonlinear optical property and photoinduced anisotropy of a novel azobenzene-containing fluorinated polyimide

A novel azobenzene-containing fluorinated polyimide was synthesized. The nonlinear optical property and photoinduced birefringence of a polyimide thin film were investigated. Large third-order nonlinear refraction (n (2)=-4.49x10(-11) cm(2)/W) was observed in the polyimide thin film by carrying out Z-scan measurement. The polyimide thin film exhibited larger nonlinear refraction than that of a mono-azo dye doped PMMA thin film (n (2)=-1.63x10(-12) cm(2)/W). The photoinduced birefringence of the polyimide thin film (a-mu n similar to 10(-2)) under different pump intensities was investigated; it was much larger than that of the mono-azo dye doped PMMA thin film (a-mu n similar to 10(-3)). Moreover, the time constants for birefringence growth and relaxation processes were determined.