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Development of optical second-order nonlinear optical material made of metallic nanowire arrays

金属纳米线阵列光学二阶非线性光学材料的研制

基本信息

批准号：
16510083
负责人：
MIZUTANI Goro
金额：
$ 2.69万
依托单位：
Japan Advanced Institute of Science and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2007
项目状态：
已结题

项目摘要

We have observed optical second harmonic generation (SHG) from metallic nanowire arrays for the first time. We used Au nanowires of 60nm width on facted NaC1 (110) faces fabricated by shadow deposition method. From the polarization and photon energy dependence, we have found that Au behaves as an ideal metal and its optical property is dominated by the effect of the depolarization field for the photon energy below 1.5eV.We have fabricated Pt nanowire arrays of 9nm and 20nm widths and have observed their SH response. The SH response was anisotropic due to the anisotropic shapes of the cross sections of the nanowires caused by the low mobility of Pt atoms during wire growth. The second-order nonlinear susceptibility element X^<(2)>_<222> was found to be large, where 2 represents the direction perpendicular to both the nanowire axes and the array planes. The specific feature of the Pt nanowires is that the cross section has an anisotropic shape and the poor dielectric shielding due to the large imaginary part of the dielectric function.We have observed SHG from Cu nanowire arrays with the wire widths of 14 to 19nm, in order to generalize this study to other metallic species. The dielectric and nonlinear optical properties of Cu nanowires could be explained by using a local plasmon model and were reproduced by electromagnetic numerical calculation incorporating the retardation effect. The response of the nanowires is that of a local plasmon when the incident field is perpendicular to the nanowire axes, while it is described by lightning-rod effect when the incident field is parallel to the nanowire axes.From the results of these works we could pick up at least three types of nonlinear effect of metallic nanowires, and have contributed considerably to the understanding of the nonlinear optical effect of metallic nanostructures.

首次观察到金属纳米线阵列的光学二次谐波产生。我们使用阴影沉积法在Facted NaC 1（110）面上制备了宽度为60 nm的Au纳米线。从偏振态和光子能量的依赖关系，我们发现Au表现为一种理想的金属，当光子能量低于1.5eV时，其光学性质主要受退偏振场的影响。我们制备了9 nm和20 nm宽的Pt纳米线阵列，并观察了它们的SH响应。SH响应是各向异性的，由于各向异性形状的纳米线的横截面所造成的低迁移率的Pt原子在线生长过程中。发现二阶非线性极化率元素X^<（2）>_<222>较大，其中2表示垂直于纳米线轴和阵列平面的方向。Pt纳米线的特殊之处在于其横截面具有各向异性的形状和介电函数虚部较大导致的介电屏蔽差.为了将这一研究推广到其他金属物种，我们观察到了线宽为14 - 19 nm的Cu纳米线阵列的倍频现象.铜纳米线的介电和非线性光学性质可以用局域等离子体模型来解释，并通过电磁数值计算再现延迟效应。当入射场垂直于纳米线轴线时，纳米线的响应为局域等离子体激元响应，而当入射场平行于纳米线轴线时，纳米线的响应为避雷针效应响应，从这些结果中我们可以发现至少三种类型的金属纳米线非线性效应，对理解金属纳米线的非线性光学效应有很大贡献。