Zhang Wending, Zhang Lu, Lu Fanfan, Bai Donghui, Xue Tianyang, Meng Chao, Liu Min, Mao Dong, Gao Feng, Mei Ting
MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions and Shaanxi Key Laboratory of Optical Information Technology, School of Physics Science and Technology, Northwestern Polytechnical University, Xi'an 710072, China.
Nanoscale. 2020 Apr 3;12(13):7045-7050. doi: 10.1039/c9nr09710d.
We present the plasmon-enhanced nonlinear nanofocusing of a gold (Au) nanoprism array substrate (ANAS) driven via an ultrafast azimuthal vector beam (AVB). Theoretical calculations show that the electric-field intensity of the ANAS vertically excited via the femtosecond AVB is higher than that of LPB excitation. In this experiment, the second-order surface nonlinear optical response of the ANAS is adopted to examine the nonlinear plasmonic nanofocusing of the ANAS, and it was observed that the second harmonic (SH) intensity of the ANAS excited via the femtosecond AVB is ∼3.8 times higher than that of LPB excitation, revealing that the ANAS under AVB excitation has a better nonlinear plasmonic nanofocusing characteristic than that under LPB excitation. Furthermore, the GaSe nanosheets are transferred on the ANAS to examine the nonlinear plasmonic nanofocusing of the ANAS. The SH intensity of the GaSe nanosheets deposited on the ANAS via the femtosecond AVB excitation has been enhanced ∼4.7 times than that of LPB excitation, indicating that the ANAS via AVB excitation has better nonlinear plasmonic nanofocusing than that of LPB excitation. This method may be used as a nonlinear nanofocusing light source to increase the light-matter nonlinear interaction.
我们展示了通过超快方位角矢量光束（AVB）驱动的金（Au）纳米棱镜阵列衬底（ANAS）的等离子体增强非线性纳米聚焦。理论计算表明，通过飞秒AVB垂直激发的ANAS的电场强度高于线偏振光束（LPB）激发的电场强度。在本实验中，采用ANAS的二阶表面非线性光学响应来研究ANAS的非线性等离子体纳米聚焦，并且观察到通过飞秒AVB激发的ANAS的二次谐波（SH）强度比LPB激发的强度高约3.8倍，这表明在AVB激发下的ANAS比在LPB激发下具有更好的非线性等离子体纳米聚焦特性。此外，将GaSe纳米片转移到ANAS上以研究ANAS的非线性等离子体纳米聚焦。通过飞秒AVB激发沉积在ANAS上的GaSe纳米片的SH强度比LPB激发增强了约4.7倍，表明通过AVB激发的ANAS比LPB激发具有更好的非线性等离子体纳米聚焦。该方法可作为非线性纳米聚焦光源，以增强光与物质的非线性相互作用。
