Narrow high refractive index nanowires sustain weakly guided modes with significant mode volume outside of the nanowire. This modal spillover makes them interesting photonic materials for a multitude of applications. In this article we fabricate dimers of nanowires with lengths up to 1.4 μm, radii down to 55 nm, and edge-to-edge separation down to 60 nm through anisotropic etching from crystalline silicon (Si). We investigate how the properties of the weakly confined fundamental HE_1,1 mode in Si nanowires are modified by their integration into dimers. In particular, we characterize through a combination of experimental spectroscopy and numerical electromagnetic simulations how the lifting of the degeneracy of HE_1,1x and HE_1,1y modes in dimers of Si nanowires generates linear birefringence, spin angular momentum, and superchirality. Achiral Si nanowire dimers are found to create locations of strongly enhanced near-field chirality in the gap between the nanowires, where the field can interact with the ambient medium.

中文翻译：

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在硅纳米线二聚体中产生光学双折射和手性

狭窄的高折射率纳米线在纳米线外部以显着的模式体积维持弱导模。这种模态溢出使它们成为用于多种应用的有趣的光子材料。在本文中，我们通过从晶体硅（Si）进行各向异性蚀刻，制造了纳米线的二聚体，其长度最大为1.4μm，半径最小为55 nm，边缘到边缘的间距最小为60 nm。我们研究了如何通过将其集成到二聚体中来修饰Si纳米线中有限受限的基本HE _1,1模式的性质。特别是，我们通过结合实验光谱学和数值电磁模拟来表征如何消除HE _{1,1 x}和HE _{1,1 y}的简并性Si纳米线的二聚体中的模态产生线性双折射，自旋角动量和超手性。发现非手性Si纳米线二聚体在纳米线之间的间隙中产生强烈增强的近场手性的位置，在该处场可与环境介质相互作用。