• Chinese Optics Letters
  • Vol. 21, Issue 2, 023602 (2023)
Jun Liu1, Xiaoshu Zhu1, Juanzi He1, Yifan Zhou1, Mingqian Shi1, Zhaofu Qin1, Shuming Wang1、2、3、*, and Zhenlin Wang1、2
Author Affiliations
  • 1National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
  • 2Key Laboratory of Intelligent Optical Sensing and Manipulation, Ministry of Education, Nanjing University, Nanjing 210093, China
  • 3Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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    DOI: 10.3788/COL202321.023602 Cite this Article Set citation alerts
    Jun Liu, Xiaoshu Zhu, Juanzi He, Yifan Zhou, Mingqian Shi, Zhaofu Qin, Shuming Wang, Zhenlin Wang. Metasurfaces enabled dual-wavelength decoupling of near-field and far-field encoding[J]. Chinese Optics Letters, 2023, 21(2): 023602 Copy Citation Text show less

    Abstract

    The metasurface is a platform with a small footprint and abundant functionalities. With propagation phase and geometric phase, polarization multiplexing is possible. However, different response behaviors of propagation phase and geometric phase to wavelength have not been fully employed to widen the capabilities of metasurfaces. Here, we theoretically demonstrate that metasurfaces can achieve near-field and far-field decoupling with the same polarization at two wavelengths. First, we found a set of pillars whose propagation phase difference between two wavelengths covers the full range of 2π. Then, by rotating pillars to control the geometric phase, the phase at both wavelengths can cover the full range of 2π. Finally, by means of interference principle, arbitrary independent coding for the near field and far field of dual wavelengths is realized. In addition, when the far-field function is focusing, the focused spot is close to the diffraction limit, and, when the NA of the lens is very small, the final output focal length is four times of initial input focal length. This work circumvents the strong wavelength-dependent limitation of planar devices and paves the way toward designing multi-wavelength and multi-functional metadevices for scenarios such as AR applications, fluorescence microscopy, and stimulated emission depletion microscopy.
    Eout,β=E0ξ1βeiϕ1β+E0ξ2βeiϕ2β=E0eiϕ1β+ϕ2β2[(ξ1β+ξ2β)cos(ϕ1βϕ2β2)+i(ξ1βξ2β)sin(ϕ1βϕ2β2)],

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    Iout,β=E02[(ξ1β+ξ2β)2cos2(ϕ1βϕ2β2)+(ξ1βξ2β)2sin2(ϕ1βϕ2β2)].

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    Eout,β=E0eiϕ1β+ϕ2β2(ξ1β+ξ2β).

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    Eout,β=iE0eiϕ1β+ϕ2β2(ξ1βξ2β).

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    V=Iout,β,maxIout,β,minIout,β,max+Iout,β,min=2ξ1βξ2βξ1β2+ξ2β2.

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    2πλ(r2+f2f)=2πλ(4r2+f2f),

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    f=4f.

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    Jun Liu, Xiaoshu Zhu, Juanzi He, Yifan Zhou, Mingqian Shi, Zhaofu Qin, Shuming Wang, Zhenlin Wang. Metasurfaces enabled dual-wavelength decoupling of near-field and far-field encoding[J]. Chinese Optics Letters, 2023, 21(2): 023602
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