Research ArticleAPPLIED OPTICS

Single-pixel computational ghost imaging with helicity-dependent metasurface hologram

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Science Advances  08 Sep 2017:
Vol. 3, no. 9, e1701477
DOI: 10.1126/sciadv.1701477

Figures

  • Fig. 1 Experimental setup and metasurface structure.

    (A) Schematic experimental setup of computational GI with reflective metasurface. (B) One-pixel cell structure of the metasurface. (C) Scanning electron microscopy image of the metasurface nanorod structure. (D) Schematic diagram of reflective metasurface hologram with LCP and RCP light.

  • Fig. 2 Simulated and experimental results with different GI algorithms.

    (A) Original image. (B) Experimental metasurface holographic image. (C) The intensity distribution of metasurface holographic image in 51 × 51 pixels. Simulated reconstructed image (51 × 51 pixels) from holographic image with different algorithms: (D) standard GI, (E) DGI, and (F) CGI. The sampling measurement is set to N = 51 × 51 = 2601 in the simulation. Experimentally reconstructed image with different algorithms: (G) GI, (H) DGI, and (I) CGI. The incident light is LCP, and the sampling measurement N is 668 in the experiment.

  • Fig. 3 Experimentally recovered images (51 × 51 pixels) and their PSNR with CGI algorithm.

    The polarization state of incident light is LCP in the first row and RCP in the second row. The sampling measurements were as follows: N = 200 in (A) and (E), N = 350 in (B) and (F), N = 500 in (C) and (G), and N = 650 in (D) and (H). (I) Experimental PSNR at different measurement N for both LCP and RCP cases.

  • Fig. 4 Optical encryption proposal and its vulnerability test.

    (A) Scheme of the optical encryption based on CGI with helicity-dependent metasurface hologram. All holographic and CGI recovered images come from the simulation with a 101 pixel × 101 pixel 1608 original image and measurement N = 8000. Experimentally reconstructed image with LCP light: (B) 15% key mismatch, (C) 30% key mismatch, and (D) 45% key mismatch. Their corresponding recovered hologram image with 0% key mismatch is Fig. 3C. Experimentally reconstructed image with different key ratios of LCP and RCP light: (E) 10% LCP versus 90% RCP, (F) 30% LCP versus 70% RCP, and (G) 50% LCP versus 50% RCP. The key numbers of RCP light in (E) to (G) are fixed at 500.