Wang Xia, Yao Linhua, Chen Xiaodie, Dai Hongwei, Wang Mingshan, Zhang Luman, Ni Yun, Xiao Lixia, Han Jun-Bo
School of Mathematics and Physics , Wenhua College , Wuhan 430074 , P. R. China.
Wuhan National High Magnetic Field Center and School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , P. R. China.
ACS Appl Mater Interfaces. 2019 Sep 4;11(35):32469-32474. doi: 10.1021/acsami.9b08935. Epub 2019 Aug 23.
The third-order optical nonlinearities and the hot electron relaxation time (τ) of random-distributed gold nanorods arrays on glass (R-GNRA) have been investigated by using Z-scan and optical Kerr effect (OKE) techniques. Large third-order optical susceptibility (χ) with the value of 2.5 × 10 esu has been obtained around the plamsonic resonance peak under the excitation power intensity of 0.1 GW/cm. Further decrease of the excitation power intensity down to 0.3 MW/cm will lead to the significant increase of χ up to 6.4 × 10 esu. The OKE results show that the relaxation time of R-GNRA around the plasmonic peak is 13.9 ± 0.4 ps, which is more than 4 times longer than those of the individual gold nanostructures distributed in water solutions. The Finite-difference time domain simulations demonstrate that this large enhancement of χ and slow down of τ are caused by the gap-induced large local field enhancement of GNRs dimers in R-GNRA. These significant results offer great opportunities for plasmonic nanostructures in applications of photonic and photocatalytic devices.
利用Z扫描和光学克尔效应（OKE）技术研究了玻璃上随机分布的金纳米棒阵列（R-GNRA）的三阶光学非线性和热电子弛豫时间（τ）。在0.1 GW/cm的激发功率强度下，在等离子体共振峰附近获得了值为2.5×10 esu的大三阶光学极化率（χ）。将激发功率强度进一步降低至0.3 MW/cm会导致χ显著增加至6.4×10 esu。OKE结果表明，R-GNRA在等离子体峰附近的弛豫时间为13.9±0.4 ps，比水溶液中单个金纳米结构的弛豫时间长4倍多。时域有限差分模拟表明，χ的这种大幅增强和τ的减慢是由R-GNRA中GNR二聚体的间隙诱导大局部场增强引起的。这些显著结果为等离子体纳米结构在光子和光催化器件应用中提供了巨大机遇。
