• Chinese Optics Letters
  • Vol. 19, Issue 2, 023601 (2021)
Ming Deng, Tangxuan Ren, Jian Wang, and Lin Chen*
Author Affiliations
  • Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
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    DOI: 10.3788/COL202119.023601 Cite this Article Set citation alerts
    Ming Deng, Tangxuan Ren, Jian Wang, Lin Chen. Doublet achromatic metalens for broadband optical retroreflector[J]. Chinese Optics Letters, 2021, 19(2): 023601 Copy Citation Text show less

    Abstract

    A retroreflector that reflects light along its incident direction has found numerous applications in photonics, but the available metasurface schemes suffer from the issue of narrow bandwidth and/or a single angle of incidence. Here, a retroreflector using double layers of achromatic gradient metasurfaces is reported, which can realize retroreflection over a continuous range of incidence angles within a wide spectral band. The first metasurface serves as a transmissive achromatic lens that performs a broadband spatial Fourier transform and its inverse, while the second metasurface works as a reflective achromatic lens that undergoes wavelength- and position-dependent phase dispersions. Using this design strategy, a near-infrared retroreflector comprised of silicon nanopillars with the cross sections of square pillars and square holes is numerically demonstrated, providing a high-performance retroreflection for polarization-independent incident light waves over a continuous range of incidence angles from 0° to 16° within an extremely broad wavelength range between 1.35 and 1.95 μm. The scheme herein can offer a design strategy of broadband retroreflectors and impact numerous photonics applications.
    φL(r0,λ)φL(0,λ)=n2πλ(F2+r02F),

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    sinθ=nl(θ)/F,

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    φR(R0,λ)R0|R0=l(θ)=2(2πλ)sinθ,

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    φR(R0,λ)φR(0,λ)=2πλnFR02.

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    Eref,v(x,y=0,z,θ,λ)=(2π)2+Av(kx,ky,θ,λ)ejkxxj(2π/λ)2kx2ky2(zz0)dkxdky,

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    ΔAv(kx,ky,θ,λ)=+ΔEref,v(x,y,z=z0,θ,λ)ejkxxjkyydxdy,

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    rret(θ,λ)=[+Eref,v(x,y,z=z0,θ,λ)ej2πλxsinθdxdy]/[+Einc,v(x,y,z=z1,θ,λ)ej2πλxsinθdxdy],

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    rnor(θ,λ)=[+Eref,v(x,y,z=z0,θ,λ)ej2πλxsinθdxdy]/[+Einc,v(x,y,z=z1,θ,λ)ej2πλxsinθdxdy].

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    Ming Deng, Tangxuan Ren, Jian Wang, Lin Chen. Doublet achromatic metalens for broadband optical retroreflector[J]. Chinese Optics Letters, 2021, 19(2): 023601
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