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Selectively steering photon spin angular momentum via electron-induced optical spin Hall effect

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Science Advances  28 Apr 2021:
Vol. 7, no. 18, eabf8011
DOI: 10.1126/sciadv.abf8011
  • Fig. 1 Schematic of spin component detection.

    (A) Schematic illustration of electron-induced OSHE. Symmetrical Au nanorectangle antenna under electron beam excitation at the upper edge generates asymmetrical circularly polarized radiation. (B) Schematic illustration of photon spin analyzing. (C) Angle-resolved CL polarimetry for measurements of the circularly polarized radiation. The quarter wave plate and linear polarizer are used to extract circularly polarized components of CL emission.

  • Fig. 2 Analyses of spin states.

    (A) Experimental total, LCP, and RCP CL spectra obtained from Au nanoantenna with the size of 200 × 80 nm under 30-keV electron beam excitation. The stimulation position is located at middle of the upper edge of the Au nanoantenna, with the measured CL chirality corresponding to the right ordinate. (B) Measured angular patterns of horizontal (IH on the left) and vertical (IV on the right) components for CL signals. The stimulation position is located at the middle of the upper edge of the Au nanoantenna, with the detection wavelength at 650 nm. (C) Measured angular patterns of RCP (left) and LCP (right) components for CL signals. The stimulation position and detection wavelength are the same as in (B). (D) Measured angular pattern of S0 Stokes parameter. (E) Measured angular pattern of S3 Stokes parameter. All patterns are normalized to 1. Axis in (C) to (E) is the same as in (B).

  • Fig. 3 Manipulation of photon spin angular momentum.

    (A) Experimental normalized angular CL S3 patterns obtained from Au nanoantenna at the size of 200 × 80 nm, with electron stimulation voltage of 30 keV. Stimulation positions located at the middle of the upper edge, center of the antenna, and middle of the lower edge, which are marked with a red point on the pseudocolor scanning electron microscopy (SEM) image of the Au nanoantenna. Collected wavelengths are 600 and 650 nm, respectively. (B) Simulated angular CL S3 patterns of the Au nanoantenna. Electron beam excitation positions and collected wavelengths are the same as in (A). (C) Scattering ratio as function of wavelength for different excitation positions. The horizontal dashed line corresponds to the averaged scattering ratio. Error bar represents the uncertainty of scattering ratio in three experiments. (D) S3 ratio (ρ) as a function of wavelength for different excitation positions. S3 ratio (ρ) is defined as |S3left|/S3right, where S3left (S3right) is the integrated S3 value of the left (right) half of the angular hemisphere. The horizontal dashed line corresponds to the averaged ρ. Error bar represents the uncertainty of ρ in three experiments.

  • Fig. 4 Multipolar analysis of CP-resolved angular patterns for Au nanoantenna.

    (A) Experimental normalized angular S3 patterns obtained from Au nanoantennas at the size of 200 × 80, 200 × 70, 200 × 60, 180 × 60, and 160 × 60 nm. The stimulation position is located at the middle of the upper edge of the Au nanoantenna, with 30-keV electron beam excitation. The collected wavelength is 650 nm. (B) Simulated angular S3 patterns of Au nanoantenna at different sizes. The Au nanoantenna size, excitation position, and collected wavelength are the same as in (A). (C) Simulated scattering intensity of various multipole moments in nanoantenna with the size of 200 × 80 nm. Spectra correspond to total intensity and intensity of P, Q, and M moments. (D) Simulated scattering intensity of various electrical dipole components in the nanoantenna with the size of 200 × 80 nm. Spectra correspond to the intensity of Px, Py, and Pz components. Inset: axis (xyz) of the dipole orientation.

  • Fig. 5 Schematic of spin-dependent binary encoding.

    (A) Functional unit for spin-dependent binary encoding. With electron beam excitation positions located at the middle of the upper edge, middle of the lower edge, and center of the nanoantenna, which are marked with three points on the pseudocolor SEM image of the Au nanoantenna; corresponding S3 patterns are defined as 0, 1, and erasure code for binary encoding. (B) ASCII codes of capital letters “P” and “K” for the binary encoding. (C) Angular CL S3 patterns with the electron beam moving along two paths corresponding to ASCII codes, which output the binary sequences of “01010000” and “01001011” corresponding to capital letters “P” and “K,” respectively.

Supplementary Materials

  • Supplementary Materials

    Selectively steering photon spin angular momentum via electron-induced optical spin Hall effect

    Cheng Chi, Qiao Jiang, Zhixin Liu, Liheng Zheng, Meiling Jiang, Han Zhang, Feng Lin, Bo Shen, Zheyu Fang

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