Zhang Xin, Hu Yanwen, Lin Haolin, Yin Hao, Li Zhen, Fu Shenhe, Chen Zhenqiang
College of Physics and Optoelectronic Engineering, Jinan University, Guangzhou 510632, China.
Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Guangzhou 510632, China.
Nanophotonics. 2024 Jul 11;13(20):3867-3876. doi: 10.1515/nanoph-2024-0206. eCollection 2024 Aug.
We demonstrate a technique for flexibly controlling subwavelength focusing and scanning, by using the Fourier translation property of a topology-preserved flat lens. The Fourier transform property of the flat lens enables converting an initial phase shift of light into a spatial displacement of its focus. The flat lens used in the technique exhibits a numerical aperture of 0.7, leading to focusing the incident light to a subwavelength scale. Based on the technique, we realize flexible control of the focal positions with arbitrary incident light, including higher-order structured light. Particularly, the presented platform can generate multifocal spots carrying optical angular momentum, with each focal spot independently controlled by the incident phase shift. This technique results in a scanning area of 10 μm × 10 μm, allowing to realize optical scanning imaging with spatial resolution up to 700 nm. This idea is able to achieve even smaller spatial resolution when using higher-numerical-aperture flat lens and can be extended to integrated scenarios with smaller dimension. The presented technique benefits potential applications such as in scanning imaging, optical manipulation, and laser lithography.
我们展示了一种通过使用拓扑保持平面透镜的傅里叶平移特性来灵活控制亚波长聚焦和扫描的技术。平面透镜的傅里叶变换特性能够将光的初始相移转换为其焦点的空间位移。该技术中使用的平面透镜的数值孔径为0.7，可将入射光聚焦到亚波长尺度。基于该技术，我们实现了对任意入射光（包括高阶结构化光）焦点位置的灵活控制。特别地，所提出的平台可以产生携带光学角动量的多焦点光斑，每个焦点光斑由入射相移独立控制。该技术的扫描面积为10μm×10μm，能够实现空间分辨率高达700nm的光学扫描成像。当使用更高数值孔径的平面透镜时，这一理念能够实现甚至更小的空间分辨率，并且可以扩展到更小尺寸的集成场景。所提出的技术有利于扫描成像、光学操纵和激光光刻等潜在应用。
