Wang Chengmiao, Lin Yu, Han Yeming, Wei Yupei, Wang Bin, Jin Zhao, Deng Yongbo
Opt Express. 2023 Sep 25;31(20):33596-33607. doi: 10.1364/OE.500688.
To address the challenges posed by computational resource consumption and data volume in the development of large-aperture metalenses, a design method for concentric-ring metalens based on two-dimensional unit splicing is proposed in this paper. In the method, the unit structure library is constructed through global traversal under the machining process constraints. The phase matching is performed for two polarization states with specific weights and the design of binary-height, concentric-ring structures with arbitrary polarization sensitivity is realized, whose focusing efficiency (the encircled power within 3×FWHM of the focal spot divided by the near-field outgoing power) is up to 90%. Based on this method, a polarization-insensitive metalens with a design wavelength of 10µm, diameter of 2 cm, and numerical aperture of 0.447 is obtained. The method combines the advantages of lower computation requirements for a building block array of a metalens and lower structure data for a concentric-ring metalens. Consequently, it becomes possible to reduce calculation and processing costs by several orders of magnitude during the development process of metalenses with diameters ranging from 10 to 10 wavelengths. The resulting focusing efficiency can approach the upper limit achievable through global structural optimization and significantly surpass that of binary-height Fresnel lenses.
为应对大口径超构透镜开发过程中计算资源消耗和数据量带来的挑战，本文提出了一种基于二维单元拼接的同心环超构透镜设计方法。该方法在加工工艺约束下通过全局遍历构建单元结构库，对两种具有特定权重的偏振态进行相位匹配，实现了具有任意偏振灵敏度的二值高度同心环结构设计，其聚焦效率（焦斑3×半高宽内的环绕功率除以近场出射功率）高达90%。基于该方法，获得了一种设计波长为10µm、直径为2 cm、数值孔径为0.447的偏振不敏感超构透镜。该方法结合了超构透镜积木式阵列计算需求较低和同心环超构透镜结构数据较少的优点。因此，在直径从10到10个波长的超构透镜开发过程中，有可能将计算和处理成本降低几个数量级。由此得到的聚焦效率可接近通过全局结构优化所能达到的上限，并显著超过二值高度菲涅耳透镜的聚焦效率。
