Ultrafast third-order optical nonlinearity of polycyanopyridine

Abstract

A novel plasma-polymerized 4-cyanopyridine (PP4CPD) thin film of desired thickness was prepared by plasma polymerization under different glow discharge conditions. The effect of the discharge power on the chemical structure and surface compositions of the PP4CPD films was investigated by FT-IR, UV–Vis and X-ray photoelectron spectroscopy (XPS). A high retention of the aromatic ring structure of the starting monomer in the deposited plasma films is obtained at a low discharge power. A red shift in the maximum absorption wavelength ( λ max) for PP4CPD films was observed as compared with the monomer absorption spectrum. The atomic force microscopy (AFM) measurement shows that the PP4CPD film with quite a smooth surface could be grown under a relatively low discharge power. A femtosecond time-resolved optical Kerr effect (OKE) technique has been applied to investigate the third-order nonlinearity of the plasma PP4CPD film. For the first time, a non-resonant optical Kerr effect and ultrafast response of polycyanopyridine was observed.