Design of large scale plasmonic nanoslit arrays for arbitrary mode conversion and demultiplexing
Design of large scale plasmonic nanoslit arrays for arbitrary mode conversion and demultiplexing
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DOI：
10.1117/12.2052104
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发表时间：
2014-05
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通讯作者：
P. Wahl;Takuo Tanemura;N. Vermeulen;J. Van Erps;D. Miller;H. Thienpont
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作者：
P. Wahl;Takuo Tanemura;N. Vermeulen;J. Van Erps;D. Miller;H. Thienpont
我们提出了一种迭代设计方法，利用薄金属膜中非周期性随机分布的狭缝阵列，实现任意模式到聚焦表面等离子体激元的耦合和模式转换。由于狭缝之间的距离很小，狭缝的数量很大，显着的互耦合之间发生的狭缝，这使得由狭缝散射场的精确计算困难。我们使用一个准确的模态源辐射器模型，以有效地计算在一个显着更短的时间相比，三维（3D）全场严格的模拟领域，从而有效地实现迭代优化。由于我们的模型考虑了狭缝之间的相互耦合，因此可以将源波和聚焦表面等离子体激元的狭缝散射纳入优化方案中。我们将这种方法应用于设计用于任意光纤模式的各种类型的耦合器和将三个正交光纤模式聚焦到三个不同焦点的模式解复用器。最后，我们使用全矢量三维时域有限差分（FDTD）模拟验证我们的设计结果。
We present an iterative design method for the coupling and the mode conversion of arbitrary modes to focused surface plasmons using a large array of aperiodically randomly located slits in a thin metal lm. As the distance between the slits is small and the number of slits is large, significant mutual coupling occurs between the slits which makes an accurate computation of the field scattered by the slits difficult. We use an accurate modal source radiator model to efficiently compute the fields in a significantly shorter time compared with three-dimensional (3D) full-field rigorous simulations, so that iterative optimization is efficiently achieved. Since our model accounts for mutual coupling between the slits, the scattering by the slits of both the source wave and the focused surface plasmon can be incorporated in the optimization scheme. We apply this method to the design of various types of couplers for arbitrary fiber modes and a mode demultiplexer that focuses three orthogonal fiber modes to three different foci. Finally, we validate our design results using fully vectorial 3D nite-difference time-domain (FDTD) simulations.