Optical nanofocusing on tapered metallic waveguides
Optical nanofocusing on tapered metallic waveguides
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DOI：
10.1007/s11468-006-9022-7
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发表时间：
2007-03-01
期刊：
影响因子：
3
通讯作者：
Guckenberger, Reinhard
中科院分区：
文献类型：
--
作者：
Issa, Nader A.;Guckenberger, Reinhard
锥形金属线显示出一种非凡的能力，可以“挤压”传播表面等离子体极化模式的横向范围，因为它向锥度的尖端传播。这种转变可以在远低于衍射极限的情况下继续进行，并在产生强烈近场的纳米级顶点处终止。我们执行了第一个完整的数值模拟来调查和量化这一现象。通过对吸收、辐射散射和反射的综合考虑，找到了能最大程度增强锥形导线尖端场的最佳角度。我们得到的最优参数与绝热锥化的条件相矛盾，因此提倡采用数值模拟。尽管有损耗的影响，纳米聚焦对于广泛的实用金属、可见波长和锥度几何形状仍然是高效的。不同的纳米光学应用可以直接和显著地受益于这些结果。
Tapered metal wires show a remarkable ability to 'squeeze' the lateral extent of a propagating surface-plasmon-polariton mode as it travels toward the tip of the taper. The transformation can be continued well below the diffraction limit to terminate at a nanoscale apex where intense near-fields are created. We perform the first full numerical simulations to investigate and quantify this phenomenon. We find optimal angles for maximal tip-field enhancement on conical wires by considering absorption, scattering to radiation and reflection. The optimal parameters we obtain contradict the conditions for adiabatic tapering, thereby advocating the use of numerical simulations. Despite the influence of losses, nanofocusing is still highly efficient for a broad range of practical metals, visible wavelengths and taper geometries. Diverse nano-optic applications can benefit directly and significantly from the results.