Superoscillatory optical devices have been widely investigated in the past several years. Due to their unique focusing properties, the ones that focus cylindrically polarized waves are attractive for such applications as super-resolution imaging and particle manipulation. However, the superoscillatory lenses reported for the focusing of cylindrically polarized light suffer from difficulties related to precise coaxial alignment, which might lead to the substantial distortions of the superoscillatory features. Moreover, conventional polarization converters only have a narrow bandwidth of several tens of nanometers in the visible spectrum, which limits the broadband focusing of cylindrically polarized waves. In this work, an amorphous silicon dielectric meta-atom is proposed with the integrated functions of independent polarization conversion and binary phase modulation in the visible spectrum range. Based on the proposed meta-atom, a superoscillatory dielectric metalens with a high numerical aperture (NA) of 0.93 is proposed and optimized for the broadband generating and superoscillation focusing of azimuthally polarized lights. The linearly polarized wave was first converted into azimuthally polarized ones, and then focused into a superoscillation hollow spot of azimuthal polarization (AP). The experimental results demonstrate the formation of hollow spots with inner sizes of 0.355λ‒0.490λ in the wavelength range of 518.1‒683.5 nm. This simple approach paves an alternative pathway of generating vector waves with superoscillation features for super-resolution applications.

中文翻译：

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宽带电介质金属离子，用于可见光的偏振处理和超振荡聚焦

在过去的几年中，超振荡光学器件已经得到了广泛的研究。由于其独特的聚焦特性，聚焦圆柱偏振波的聚焦器对于诸如超分辨率成像和粒子操纵等应用具有吸引力。然而，据报道用于聚焦圆柱偏振光的超级振荡透镜具有与精确的同轴对准有关的困难，这可能导致超级振荡特征的实质性变形。而且，常规的偏振转换器在可见光谱中仅具有几十纳米的窄带宽，这限制了圆柱形偏振波的宽带聚焦。在这项工作中，提出了一种在可见光谱范围内具有独立偏振转换和二进制相位调制的集成功能的非晶硅介电原子。在提出的亚原子的基础上，提出了一种具有0.93的高数值孔径（NA）的超振荡介电金属，并对其进行了优化，以用于方位偏振光的宽带产生和超振荡聚焦。线偏振波首先转换为方位角偏振波，然后聚焦到方位角偏振（AP）的超振荡空心点。实验结果表明在518.1‒683.5 nm波长范围内形成了内部尺寸为0.355λ‒0.490λ的空心斑点。