大数值孔径介质结构透镜

提出了一种新型大数值孔径介质结构透镜，能量利用率达到了44%。通过数值仿真FDTD计算证明该聚焦器件能实现高的能量利用率和接近衍射极限的聚焦光斑，且聚焦光斑的旁瓣很小。其次，对该透镜的色散性能进行了研究，发现该透镜具有与普通透镜相反的色散特性。故该透镜可以与普通透镜组合消色差。另外，该透镜克服了最小特征尺寸，实现了大数值孔径，针对波长10.6 m设计了相同口径、不同F数的介质结构透镜，最小F数达到了0.25。

Dielectric structured lens of large numerical aperture

A dielectric structured lens formed by varying the high-refractive-index square dielectric holes was proposed. This lens can realize higher energy efficiency compared with the high-refractive-index square dielectric metal structured lens. The energy efficiency has achieved 44% by finite difference and time domain(FDTD) algorithm, and the spot size leads to the diffraction limit. Second, the dispersion characteristic of the lens was researched, it has the counter dispersion characteristic with the geometrical optics lens, so lens group make up of those dielectric structured lens and the geometrical optics lens can be used to clear dispersion. In addition, it overcomes the limitation of feature size of the large numerical aperture(NA) lens, so the large NA lens can be achieved. Four lens with the same aperture but different focus length were designed for the wavelength 10.6m. The smallest F number has reached 0.25.