Key Laboratory of Optoelectronic Technology and Systems (Chongqing University), Ministry of Education, and Key Disciplines Lab of Novel Micro-nano Devices and System Technology, Chongqing University, 173 Shazheng Street, Shapingba, Chongqing 400044, China.
National Center for Nanoscience and Technology, No. 11 Zhong Guan CunBei Yi Tiao, Beijing 100190, China.
Sci Rep. 2016 Nov 23;6:37776. doi: 10.1038/srep37776.
The generation of a sub-diffraction optical hollow ring is of great interest in various applications, such as optical microscopy, optical tweezers, and nanolithography. Azimuthally polarized light is a good candidate for creating an optical hollow ring structure. Various of methods have been proposed theoretically for generation of sub-wavelength hollow ring by focusing azimuthally polarized light, but without experimental demonstrations, especially for sub-diffraction focusing. Super-oscillation is a promising approach for shaping sub-diffraction optical focusing. In this paper, a planar sub-diffraction diffractive lens is proposed, which has an ultra-long focal length of 600 λ and small numerical aperture of 0.64. A sub-diffraction hollow ring is experimentally created by shaping an azimuthally polarized wave. The full-width-at-half-maximum of the hollow ring is 0.61 λ, which is smaller than the lens diffraction limit 0.78 λ, and the observed largest sidelobe intensity is only 10% of the peak intensity.
亚波长光学中空环的产生在各种应用中引起了极大的关注，例如光学显微镜、光镊和纳米光刻。角向偏振光是产生光学中空环结构的理想选择。已经提出了各种理论方法来通过聚焦角向偏振光来产生亚波长中空环，但没有实验证明，特别是对于亚衍射聚焦。超振荡是一种很有前途的亚衍射光学聚焦整形方法。本文提出了一种平面亚衍射衍射透镜，其具有 600λ 的超长焦距和 0.64 的小数值孔径。通过对角向偏振光进行整形，实验上产生了亚衍射中空环。中空环的半最大值全宽为 0.61λ，小于透镜的衍射极限 0.78λ，观察到的最大旁瓣强度仅为峰值强度的 10%。
