Abstract
We propose a metalens for coaxial double wavelength focusing. One focusing spot is a circular solid spot, and the other focusing spot is a doughnut-shaped spot that is circling the solid spot. The designed metalens was composed of a meta-molecular nanostructured cell array. Each meta-molecular nanostructured cell was divided into four squares. Two slots with exactly the same shape, but usually with the rotation angle measured clockwise from the positive x axis, are etched into the gold film in two diagonally connected squares. Another two slots with the same shape but with the rotation angle measured counter-clockwise from the positive x axis are etched into another two diagonally connected squares in the same cell. The lasers with two different wavelengths are transformed into right-handed and left-handed circularly polarized beams, respectively. The two sets of slots with different azimuthal rotations modulated the phases of incident right-handed and left-handed circularly polarized beams independently. The numerical simulation with finite-difference time-domain (FDTD) software was carried out, and the experimental verification was also implemented. Both the experimental result and the numerical simulation agree well with the theoretical design.
© 2020 Chinese Laser Press
PDF Article
More Like This
Sub-wavelength tight-focusing of terahertz waves by polarization-independent high-numerical-aperture dielectric metalens
Hao Chen, Zhixiang Wu, Zeyu Li, Zhenfei Luo, Xue Jiang, Zhongquan Wen, Liguo Zhu, Xun Zhou, Hua Li, Zhengguo Shang, Zhihai Zhang, Kun Zhang, Gaofeng Liang, Senlin Jiang, Lianghui Du, and Gang Chen
Opt. Express 26(23) 29817-29825 (2018)
Cited By
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
Contact your librarian or system administrator
or
Login to access Optica Member Subscription