Photonics Research, Volume. 10, Issue 7, 1695(2022)

All dielectric metasurfaces for spin-dependent terahertz wavefront control

Tong Wu1, Huifang Zhang2,4、*, Sivaloganathan Kumaran2, Yuehong Xu1, Qingwei Wang1, Wladislaw Michailow2, Xueqian Zhang1,5、*, Harvey E. Beere2,6、*, David A. Ritchie2, and Jiaguang Han1,3,7、*
Author Affiliations
  • 1Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, and Key Laboratory of Optoelectronics Information and Technology, Ministry of Education of China, Tianjin 300072, China
  • 2Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
  • 3Guangxi Key Laboratory of Optoelectronic Information Processing, School of Optoelectronic Engineering, Guilin University of Electronic Technology, Guilin 541004, China
  • 4e-mail: hz372@cam.ac.uk
  • 5e-mail: alearn@tju.edu.cn
  • 6e-mail: heb1000@cam.ac.uk
  • 7e-mail: jiaghan@tju.edu.cn
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    Figures & Tables(6)
    (a) Schematic of the spin-dependent metasurface, which consists of PBOEs and can generate two arbitrarily designable beam functions, F1 and F2, under orthogonally circularly polarized incidences. (b) Schematic of a rotated constituent PBOE marked by the red rectangular post in (a). (c) and (d) The simulated transport phase shifts and the corresponding transmission amplitudes of all the 15 PBOEs.
    (a) Simulated electric field distributions of Ex (top row, in the x-z cross section) and Ey (bottom row, in the y-z cross section) at 1.0 THz of the 8 fundamental PBOEs under x- and y-polarized incidences, respectively. (b) and (c) Simulated transmission amplitude spectra |tyx| and |txx| of the 8 fundamental PBOEs (No.1 to No.8) with α=45° under the x-polarized incidence. (d) Calculated PCR of the 8 fundamental PBOEs. (e) Extracted |tyx|, |txx|, and PCR values at 1.0 THz.
    (a) Microscopic image of the fabricated PCD. Scale bar: 300 μm. (b) and (c) The measured normalized intensity distributions as a function of the diffraction angle and the frequency of the y- and x-polarized outputs under x-polarized input, respectively. The white dashed line in (b) indicates the theoretical angles for the +1st diffraction order. (d) The power efficiency of the PCD. The maximum power efficiency appears at 1.1 THz. (e) The normalized intensity profiles of x- and y-polarized output at 1.1 THz.
    (a) Microscopic image of a fraction of the fabricated Bessel/half-wave metasurface. Scale bar: 300 μm. (b)–(d) The measured normalized RHCP intensity distributions at the longitudinal propagation plane at x=0 and the intensity and phase profiles at the transverse plane at z=8 mm under the LHCP incidence. (e)–(g) The corresponding measured LHCP distributions under the RHCP incidence. In the measurement, the longitudinal plane spans from −5 to 5 mm along the y-direction and 1 to 12.2 mm along the z-direction, whereas the transverse plane spans from −5 to 5 mm along both the x- and y-directions. The scanning steps are 0.2, 0.2, and 0.4 mm along the x-, y-, and z-directions, respectively.
    (a) Microscopic image of a fraction of the fabricated Bessel/vortex metasurface. Scale bar: 300 μm. (b)–(d) The measured normalized RHCP intensity distributions at the longitudinal propagation plane at x=0, and the intensity and phase profiles at the transverse plane at z=5 mm under LHCP incidence. (e)–(g) The corresponding measured LHCP distributions under the RHCP incidence, in which the transverse plane is at z=8 mm.
    • Table 1. Geometrical Parameters and Relative φf of the Selected 15 PBOEs

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      Table 1. Geometrical Parameters and Relative φf of the Selected 15 PBOEs

      No.φf (deg)lf (μm)ls (μm)No.φf (deg)lf (μm)ls (μm)
      1093.55091805093.5
      222.585.54910202.54985.5
      3458047.51122547.580
      467.57645.512247.545.576
      59075.541.51327041.575.5
      6112.58035.514292.535.580
      7135501201531512050
      8157.550106    
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    Tong Wu, Huifang Zhang, Sivaloganathan Kumaran, Yuehong Xu, Qingwei Wang, Wladislaw Michailow, Xueqian Zhang, Harvey E. Beere, David A. Ritchie, Jiaguang Han. All dielectric metasurfaces for spin-dependent terahertz wavefront control[J]. Photonics Research, 2022, 10(7): 1695

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    Paper Information

    Category: Optical Devices

    Received: Apr. 28, 2022

    Accepted: May. 29, 2022

    Published Online: Jun. 29, 2022

    The Author Email: Huifang Zhang (hz372@cam.ac.uk), Xueqian Zhang (alearn@tju.edu.cn), Harvey E. Beere (heb1000@cam.ac.uk), Jiaguang Han (jiaghan@tju.edu.cn)

    DOI:10.1364/PRJ.462153

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