Synthesis and Optical Properties of 4-Nitro-4-Dimethylaminoazobenzene Coatings

4-nitro-4-dimethylaminoazobenzene (Azo) coatings were synthesized by physical vapor deposition (PVD) on sapphire substrate.The influence of the growth conditions, including the evaporation temperature, deposition rate and film thickness, on the linear/nonlinear optical properties of the Azo dye films was investigated with ultra-violet visible (UV-Vis) absorption spectroscopy and Z-scan of single pico-second laser beam.The preliminary results show that the solid azobenzene compound materials, such as Azo coatings, could be a promising candidate for fabrication of all-optical switch.To be specific, the UV-Vis spectrum of the Azo dye coating, with an optical gap of 2.71 eV, had a blue-shift of 61 nm with respect to that of Azo solution.In addition, Azo thin film exhibits the well-defined non-linear properties, including the saturated absorption and self-focusing; and the 3^rd order nonlinear susceptibility reached a magnitude order of 10^-7 (esu).