Harrison R K, Ben-Yakar Adela
J Opt Soc Am A Opt Image Sci Vis. 2015 Aug 1;32(8):1523-35. doi: 10.1364/JOSAA.32.001523.
Here we investigate the effects of absorbing media on plasmon-enhanced near-field optical energy deposition. We find that increasing absorption by the medium results in increased particle scattering at the expense of particle absorption, and that much of this increased particle scattering is absorbed by the medium close to the particle surface. We present an analytical method for evaluating the spatial distribution of near-field enhanced absorption surrounding plasmonic metal nanospheres in absorbing media using a new point-by-point method. We propose criteria to define relevant near-field boundaries and calculate the properties of the local absorption enhancement, which redistributes absorption to the near-field and decays asymptotically as a function of the distance from the particle to background levels. Using this method, we performed a large-scale parametric study to understand the effect of particle size and wavelength on the near-field absorption for gold nanoparticles in aqueous media and silicon, and identified conditions that are relevant to enhanced local infrared absorption in silicon. The presented approach provides insight into the local energy transfer around plasmonic nanoparticles for predicting near-field effects for advanced concepts in optical sensing, thin-film solar cells, nonlinear imaging, and photochemical applications.
在此，我们研究吸收介质对等离子体增强近场光能量沉积的影响。我们发现，介质吸收的增加会导致粒子散射增加，代价是粒子吸收减少，并且这种增加的粒子散射中的大部分被靠近粒子表面的介质吸收。我们提出了一种分析方法，使用一种新的逐点方法来评估吸收介质中等离子体金属纳米球周围近场增强吸收的空间分布。我们提出了定义相关近场边界的标准，并计算局部吸收增强的特性，该特性将吸收重新分配到近场，并随着距粒子距离的增加渐近衰减至背景水平。使用这种方法，我们进行了大规模的参数研究，以了解粒径和波长对水介质和硅中金纳米粒子近场吸收的影响，并确定了与硅中增强的局部红外吸收相关的条件。所提出的方法为洞察等离子体纳米粒子周围的局部能量转移提供了思路，可用于预测光学传感、薄膜太阳能电池、非线性成像和光化学应用等先进概念中的近场效应。
