Nondiffracting light beams have been attracting considerable attention for their various applications in both classical and quantum optics. Whereas substantial investigations on generation of the nondiffracting beams were made, their lateral dimension is much larger than optical wavelength. Here we present both theoretically and experimentally a study of the generation of nondiffracting light beams at deep-subwavelength scale. The highly localized light field is a result of in-phase interference of high-spatial-frequency waves generated by optical sharp-edge diffraction with a circular thin film. It is shown that the generated beam can maintain its spot size below the optical diffraction limit for a distance of up to considerable Rayleigh range. Moreover, the topological structure of both the phase and polarization of a light beam is found to be preserved when it passes through the diffractive configuration, which enables generating nondiffracting vortex beams as well as transversely polarized vector beams at deep-subwavelength scale. This work opens a new avenue to manipulate higher-order vector vortex beams at subwavelength scale and may find intriguing applications in subwavelength optics, e.g., in superresolution imaging and nanoparticle manipulation.

中文翻译：

---

非衍射结构光束的亚波长产生

非衍射光束由于其在经典光学和量子光学中的各种应用而引起了相当大的关注。尽管对非衍射光束的产生进行了大量研究，但其横向尺寸远大于光学波长。在这里，我们在理论上和实验上都研究了在深亚波长范围内无衍射光束的产生。高度局部化的光场是由圆形薄膜的光学锐边衍射产生的高空间频率波的同相干扰的结果。结果表明，所产生的光束可以将其光斑尺寸保持在光学衍射极限以下，并保持高达最大瑞利范围的距离。此外，当光束通过衍射构型时，它的相位和偏振的拓扑结构都被保留了下来，从而可以产生深亚波长尺度的非衍射涡旋光束和横向偏振矢量光束。这项工作为在亚波长范围上操纵高阶矢量涡旋光束开辟了一条新途径，并可能在亚波长光学中找到有趣的应用，例如在超分辨率成像和纳米粒子操纵中。