• Chinese Optics Letters
  • Vol. 18, Issue 4, 042401 (2020)
Jiannong Chen*, Baodong Wang, Linwei Zhu, Jing Han, and Qinfeng Xu
Author Affiliations
  • School of Physics and Opto-Electronics Engineering, Ludong University, Yantai 264025, China
  • show less
    DOI: 10.3788/COL202018.042401 Cite this Article Set citation alerts
    Jiannong Chen, Baodong Wang, Linwei Zhu, Jing Han, Qinfeng Xu. Metalens for coaxial double wavelength focusing[J]. Chinese Optics Letters, 2020, 18(4): 042401 Copy Citation Text show less

    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.
    ψ1(x,y)=2πλ1(x2+y2+f2f),(1)

    View in Article

    ψ2(x,y)=2πλ2(x2+y2+f2f)+ϕ(x,y),(2)

    View in Article

    Jiannong Chen, Baodong Wang, Linwei Zhu, Jing Han, Qinfeng Xu. Metalens for coaxial double wavelength focusing[J]. Chinese Optics Letters, 2020, 18(4): 042401
    Download Citation