Nonlinear optical point light sources through field enhancement at metallic nanocones.
Nonlinear optical point light sources through field enhancement at metallic nanocones.
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DOI：
10.1364/oe.22.015484
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发表时间：
2014-06
期刊：
影响因子：
3.8
通讯作者：
P. Reichenbach;A. Horneber;Dominik A. Gollmer;Andreas Hille;J. Mihaljević;C. Schäfer;D. Kern;A. Meixner;Dai Zhang;M. Fleischer;L. Eng
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文献类型：
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作者：
P. Reichenbach;A. Horneber;Dominik A. Gollmer;Andreas Hille;J. Mihaljević;C. Schäfer;D. Kern;A. Meixner;Dai Zhang;M. Fleischer;L. Eng
研究了一种稳定的非线性光学点光源，基于场增强在单个，尖的金纳米锥与亚波长尺寸。用近红外、聚焦的径向偏振飞秒光束激发这些锥体允许在可见光范围内的第二谐波波长（二次谐波产生，SHG）处的尖端发射。事实上，金纳米锥与超尖尖端具有有趣的非线性光学（NLO）性能的二次谐波和双光子光致发光（TPPL）发射，由于在尖端顶点结合中心对称性破缺的电场约束增强。使用两个互补的光学设置为底部或顶部照明的尖锐的尖端SHG发射从广泛的TPPL背景连续区区分。此外，将实验与理论计算进行比较表明，这些NLO签名源自纳米锥的尖端顶点或基部边缘，这显然取决于锥的大小、周围介质和照明条件。最后，它表明，尖端发射的信号消失时，从径向切换到方位角偏振。
A stable nonlinear optical point light source is investigated, based on field enhancement at individual, pointed gold nanocones with sub-wavelength dimensions. Exciting these cones with near-infrared, focused radially polarized femtosecond beams allows for tip-emission at the second harmonic wavelength (second harmonic generation, SHG) in the visible range. In fact, gold nanocones with ultra-sharp tips possess interesting nonlinear optical (NLO) properties for SHG and two-photon photoluminescence (TPPL) emission, due to the enhanced electric field confinement at the tip apex combined with centrosymmetry breaking. Using two complementary optical setups for bottom or top illumination a sharp tip SHG emission is discriminated from the broad TPPL background continuum. Moreover, comparing the experiments with theoretical calculations manifests that these NLO signatures originate either from the tip apex or the base edge of the nanocones, clearly depending on the cone size, the surrounding medium, and illumination conditions. Finally, it is demonstrated that the tip-emitted signal vanishes when switching from radial to azimuthal polarization.