Enhanced third-order nonlinear optical property of poly(3-decayl)thiophene films modified by N+ ion implantation

Poly(3-decayl)thiophene (P3DT) films implanted by 30 keV nitrogen ions (N+) with the dose range of 1015–1017 ions/cm2 were characterized by FTIR-ATR spectra, which showed that the C–H bonds of the P3DT films were largely broken and new bonds like CC, CN and CN were formed as the increasing ion fluences. 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 P3DT films was maximized to 2.61 × 10−9 esu at an ion dose of 5.73 × 1016 ions/cm2, which was almost four times larger than that of the pristine film. The enhanced third-order nonlinear properties may attribute to the enlarged expansion coefficient of the bombarded films at proper N+ ions dose.