Concentrating light strongly calls for appropriate polarization patterns of the focused light beam and for up to a full 4π solid angle geometry. Focusing on the extreme requires efficient coupling to nanostructures of one kind or another via cylindrical vector beams having such patterns, the details of which depend on the geometry and property of the respective nanostructure. Cylindrical vector beams can not only be used to study a nanostructure, but also vice versa. Closely related is the discussion of topics such as the ultimate diffraction limit, a resonant field enhancement near nanoscopic absorbers, as well as speculations about nonresonant field enhancement, which, if it exists, might be relevant to pair production in vacuum. These cases do require further rigorous simulations and more decisive experiments. While there is a wide diversity of scenarios, there are also conceptually very different models offering helpful intuitive pictures despite this diversity.

中文翻译：

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光的极端浓度和纳米级相互作用

聚光强烈要求聚焦光束的适当偏振模式和高达 4π 立体角的几何形状。关注极端需要通过具有这种图案的圆柱形矢量光束有效地耦合到一种或另一种纳米结构，其细节取决于相应纳米结构的几何形状和特性。圆柱形矢量光束不仅可用于研究纳米结构，反之亦然。密切相关的是对极限衍射极限、纳米级吸收体附近的共振场增强以及关于非共振场增强的推测等主题的讨论，如果存在，可能与真空中的成对产生有关。这些情况确实需要更严格的模拟和更具决定性的实验。