Li Huaixin, Zhang Qi, Jiang Xue, Liang Gaofeng, Wen Zhongquan, Zhang Zhihai, Shang Zhengguo, Chen Gang
Appl Opt. 2019 Oct 1;58(28):7688-7692. doi: 10.1364/AO.58.007688.
In order to realize the function of subdiffraction focusing using a single flat lens, a special metalens is proposed to modulate the circularly polarized light. Initially, the analyses indicate that the phase shift can cover [0,2π] by changing the rotation angle of a quadrangular-frustum pyramid-shaped structure from 0° to 180°, while the average amplitude transmittance can reach 96% at the wavelength of λ=1550 nm. Then, a flat metalens is designed by carefully arranging the quadrangular-frustum pyramid-shaped structures. The simulated results show that a focal spot could be obtained at the focal length of about f=2.87λ, and the focusing efficiency is ∼14.9%. Meanwhile, the full width at half maximum (FWHM) of the focusing spot is only 0.48λ, which is smaller than the diffraction limit. Furthermore, this designed metalens can function comparatively with a conventional lens in one-to-one imaging.
为了实现使用单个平面透镜的亚衍射聚焦功能，提出了一种特殊的超构透镜来调制圆偏振光。首先，分析表明，通过将四角台金字塔形结构的旋转角度从0°改变到180°，相移可以覆盖[0,2π]，而在波长λ = 1550 nm时平均振幅透过率可以达到96%。然后，通过精心排列四角台金字塔形结构设计了一个平面超构透镜。模拟结果表明，在焦距约为f = 2.87λ处可以获得一个焦点，聚焦效率约为14.9%。同时，聚焦光斑的半高宽（FWHM）仅为0.48λ，小于衍射极限。此外，这种设计的超构透镜在一对一成像中可以与传统透镜相媲美。
