A photonic hook (PH) is a high-intensity, curved focusing beam with a subwavelength waist based on the photonic nanojet effect. It is generally created by illuminating mesoscale transparent particles using optical plane waves. In this work, we numerically explore the generation of the PH supported by the Janus microcylinder under point-source illumination. To simulate the photonic intensity distributions near the shadow surface of the Janus microcylinder, a finite-difference time-domain technique is used. The power flow distributions near the Janus microcylinder are examined for working in the visible spectrum. Due to the asymmetric vortices of Poynting vectors, the PH with a large bending angle can be produced. By changing the location of the point-source illumination, the shape and curvature of the PH can be adjusted efficiently. Moreover, when the point-source illumination is located close to the Janus microcylinder, a long focal length PH can be present. Based on the numerical results, we propose a practical modeling scheme for optical imaging using a microscope where the light source is close to the target.

中文翻译：

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Janus 微柱在点光源照明下产生的光子钩

光子钩 (PH) 是一种基于光子纳米喷射效应的具有亚波长腰的高强度弯曲聚焦光束。它通常是通过使用光学平面波照射中尺度透明粒子而产生的。在这项工作中，我们数值探索了在点光源照明下由 Janus 微圆柱体支持的 PH 的产生。为了模拟 Janus 微柱面阴影表面附近的光子强度分布，使用了有限差分时域技术。检查 Janus 微柱体附近的功率流分布是否在可见光谱中工作。由于坡印廷矢量的不对称涡流，可以产生大弯曲角的 PH。通过改变点光源照明的位置，可以有效地调整 PH 的形状和曲率。而且，当点光源靠近 Janus 微柱面时，可能会出现长焦距 PH。基于数值结果，我们提出了一种使用显微镜的光学成像实用建模方案，其中光源靠近目标。