• Photonics Research
  • Vol. 13, Issue 5, 1116 (2025)
Hui Li1, Chenhui Zhao2, Wenhui Xu1, Jie Li3..., Chenglong Zheng4, Qi Tan1, Chunyu Song1, Hang Xu1,6,*, Yun Shen2,7,* and Jianquan Yao1,5,8,*|Show fewer author(s)
Author Affiliations
  • 1Key Laboratory of Opto-Electronics Information Technology (Tianjin University), Ministry of Education, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
  • 2Department of Physics, School of Physics and Materials Science, Nanchang University, Nanchang 330031, China
  • 3Sichuan Meteorological Optoelectronic Sensor Technology and Application Engineering Research Center, Chengdu University of Information Technology, Chengdu 610225, China
  • 4Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450052, China
  • 5Key Laboratory of Photonic-Electronic Integration and Communication-Sensing Convergence (Southwest Jiaotong University), Ministry of Education, Southwest Jiaotong University, Chengdu 610097, China
  • 6e-mail: xh_931119@tju.edu.cn
  • 7e-mail: shenyun@ncu.edu.cn
  • 8e-mail: jqyao@tju.edu.cn
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    DOI: 10.1364/PRJ.554358 Cite this Article Set citation alerts
    Hui Li, Chenhui Zhao, Wenhui Xu, Jie Li, Chenglong Zheng, Qi Tan, Chunyu Song, Hang Xu, Yun Shen, Jianquan Yao, "Twisted bilayer meta-device for on-demand terahertz polarization filtering," Photonics Res. 13, 1116 (2025) Copy Citation Text show less

    Abstract

    Moiré meta-devices facilitate continuous and precise modulation of optical properties through the alteration of the relative alignment, such as twisting, sliding, or rotating of the metasurfaces. This capability renders them particularly suitable for dynamic applications, including zoom optics and adaptive imaging systems. Nevertheless, such designs often sacrifice more complex functionalities, such as polarization manipulation, in favor of simplicity and tunability. Here, we propose and experimentally validate a design strategy for a twisted bilayer metasurface that exhibits both varifocal capabilities and polarization filtering properties. By selecting silicon pillars with polarization-maintaining properties for Layer I and polarization-converting properties for Layer II, the designed Moiré metasurface can become sensitive to specific polarization states. Experimental results demonstrate that the proposed design can generate on-demand terahertz (THz) focused beams, achieving an average focusing efficiency exceeding 35% under x-linearly polarized (x-LP) illumination. This is accomplished by systematically varying the twisting angles p and q of Layer I in relation to Layer II in increments of 30°. Additionally, we provide numerical evidence that the focal length of the transmitted vortex beam can be adjusted using the same approach. The Moiré meta-device platform, which is engineered to modulate optical properties via mechanical twisting, obviates the necessity for external power sources or active materials. This generalized design strategy has the potential to significantly expedite the commercialization of multifunctional metasurfaces, which can produce high-precision optics across various practical applications.
    Φ1(r,p0p)=round(r2λ·f0)·(p0p).

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    T0=[|txx|eiφxx00|tyy|eiφyy],

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    T1=Λ1TΛ11=[cos2ϕ·|txx|eiφxx+sin2ϕ·|tyy|eiφyysinϕcosϕ·(|txx|eiφxx|tyy|eiφyy)sinϕcosϕ·(|txx|eiφxx|tyy|eiφyy)sin2ϕ·|txx|eiφxx+cos2ϕ·|tyy|eiφyy],

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    T1=t2eiφxx[1+eiπ21eiπ21eiπ21+eiπ2]=2t2ei(φxx+π4)[1ii1].

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    E1=2t2eiφxx[1ii1][10]=2t2eiφxx[1i].

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    Φ2(r,p0)=round(r2λ·f0)·p0.

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    fp=πa·p·λ.

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    NA=sin(arctanL2fp),

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    T2=Λ2T1Λ21=2tei(φxx+π4)2(cos2q+sin2q)([sinq(sinq+icosq)sinq(cosq+isinq)sinq(cosqisinq)sinq(sinq+icosq)]+[cosq(cosq+isinq)cosq(sinq+icosq)cosq(sinq+icosq)cosq(cosqisinq)]),

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    E2=T2[10]=2tei(φxx+π4)2(cos2q+sin2q)([sinq(sinq+icosq)+cosq(cosq+isinq)sinq(cosqisinq)cosq(sinq+icosq)]).

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    Φ3(r,θ0,ϕ)=round(r2λ·f0)·θ0+l·ϕ,

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    E2=2t2ei(φxx+π4)[1i].(B1)

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    E2=2t2ei(φxx+π4)(1+i)[10]=2t(1+i)2ei(φxx+π4)([1i]+[1i]).(B2)

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    E2=2t2ei(φxx+π4)[1i].(B3)

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    E2=2t2ei(φxx+π4)(1i)[10]=2t(1i)2ei(φxx+π4)([1i]+[1i]).(B4)

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    Hui Li, Chenhui Zhao, Wenhui Xu, Jie Li, Chenglong Zheng, Qi Tan, Chunyu Song, Hang Xu, Yun Shen, Jianquan Yao, "Twisted bilayer meta-device for on-demand terahertz polarization filtering," Photonics Res. 13, 1116 (2025)
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