Structural characterizations and the third-order nonlinear optical properties of poly(2,5-didecyloxy)phenylene films modified by N+ ions implantation

Poly(2,5-didecyloxy)phenylene (PDDOP) films implanted by 30 keV nitrogen ions (N+) with the dose rang of 1015-1017 ions/cm2 were characterized by FTIR-ATR spectra, UV-VIS spectra and X-ray photoelectron spectroscopy, which showed that the C-H bonds of the PDDOP films were largely broken and new bonds like CC, CN and CN were formed as the increasing ion fluence. The third-order nonlinear optical susceptibilities (χ(3)) were measured by degenerate four-wave mixing (DFWM) technique at 532 nm. The results demonstrated that the (χ(3)) value of PDDOP films was maximized to 4.19 × 10−11 esu at an ion dose of 1.15 × 1017 ions/cm2, which was 4.4 times larger than that of the pristine film. The enhanced third-order nonlinear properties may attribute to the enlarged expansion coefficient and the enhanced absorption coefficient of the bombarded films at proper N+ ions dose.