Image Processing Systems Institute of the Russian Academy of Sciences, Samara, Russia.
Opt Lett. 2013 Aug 1;38(15):2702-4. doi: 10.1364/OL.38.002702.
Using the finite-difference time-domain simulation, we show that if a gradient-index or binary planar dielectric microlens that focuses light at the output surface has a near-focus subwavelength slit the focal spot width is determined by the slit width. Notably, the slit allows the output light proportion to be increased due to the surface wave scattering, thus forming a focal spot nearly devoid of side lobes. In this work, the focal spot width of λ/23 and the diffraction efficiency of focusing of 44% are achieved.
使用时域有限差分法模拟，我们表明，如果梯度折射率或二元平面介质微透镜在输出表面聚焦光，且在近焦点处有一个亚波长狭缝，则焦斑宽度由狭缝宽度决定。值得注意的是，狭缝允许由于表面波散射而增加输出光的比例，从而形成几乎没有旁瓣的焦斑。在这项工作中，实现了焦斑宽度为λ/23 和聚焦的衍射效率为 44%。
