Abstract: A soluble poly[2-methoxy-5-(3'-methyl)butoxy]-p-phenylene vinylene(MMB-PPV) was synthesized by dehydrochlorination reaction from p-methoxylphenol and isoamyl bromide as the raw materials and characterized by ¹HNMR and FTIR. The MMB-PPV films were prepared and implanted by nitrogen ion(N⁺) with the dose ranging from 3.8×10{15} to 9.6×10¹⁶ ions/cm² at an energy of 15 keV. UV-Vis spectra exhibited that the optical absorption in visible region was improved by ion implantation followed by a red shift of optical absorption threshold and the optical bandgap(E-g) between excited state and ground state was reduced from 2.12 eV to 1.81 eV with the increase of ion dose. The third-order nonlinear optical susceptibilities(χ(3)) were measured by degenerate four-wave mixing(DFWM) technique at 532 nm. Using the relative measurement method, the χ(3) value of pristine MMB-PPV film was 7.1×10^-10 esu and became larger with the ion dose increasing and reached the maximum value of 9.3×10^-9 esu at an ion dose of 3.8×10¹⁶ ions/cm² which was almost one order of magnitude higher than that of the pristine MMB-PPV film. With the continuous increase of ion dose the χ(3) value decreased gradually, and when the ion dose was 9.6×10¹⁶ ions/cm², the χ(3) value was minimized to be 1.5×10^-10 esu. Moreover, the mechanism responsible for the enhancement of χ(3) value was also discussed tentatively.

Key words: Nonlinear optics, Ion implantation, Poly[2-methoxy-5-(3'-methyl) butoxy]-p-phenylene vinylene, Degenerate four-wave mixing