Department of Physics and Advanced Materials & Manufacturing Institute, University of North Texas, Denton, Texas, 76203, USA.
Skolkovo Institute of Science and Technology, Moscow, 143026, Russia.
Sci Rep. 2018 Jan 15;8(1):780. doi: 10.1038/s41598-017-19066-3.
Gold dipole nanoantennas embedded in an organic molecular film provide strong local electromagnetic fields to enhance both the nonlinear refractive index (n) and two-photon absorption (2PA) of the molecules. An enhancement of 53× for 2PA and 140× for nonlinear refraction is observed for BDPAS (4,4'-bis(diphenylamino)stilbene) at 600 nm with only 3.7% of gold volume fraction. The complex value of the third-order susceptibility enhancement results in a sign change of n for the effective composite material relative to the pure BDPAS film. This complex nature of the enhancement and the tunability of the nanoantenna resonance allow for engineering the effective nonlinear response of the composite film.
金偶极子纳米天线嵌入有机分子膜中，提供了强局域电磁场，增强了分子的非线性折射率 (n) 和双光子吸收 (2PA)。在 600nm 时，BDPAS（4,4'-双（二苯基氨基）二苯乙烯）的 2PA 和非线性折射增强分别达到了 53×和 140×，金的体积分数仅为 3.7%。三阶极化率增强的复数值导致相对于纯 BDPAS 薄膜，有效复合材料的 n 的符号发生变化。这种增强的复杂性质和纳米天线共振的可调谐性允许对复合薄膜的有效非线性响应进行工程设计。
