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Abstract Optical chiral imaging, as an important tool in chemical and biological analysis, has recently undergone a revolution with the development of chiral metamaterials and metasurfaces. However, the existing chiral imaging approaches based on metamaterials or metasurfaces can only display binary images with 1 bit pixel depth having either black or white pixels. Here, the unique chiral grayscale imaging based on plasmonic metasurfaces of stepped V‐shaped nanoapertures is reported with both high circular dichroism and large polarization linearity in transmission. By interlacing two subarrays of chiral nanoaperture enantiomers into one metasurface, two specific linear polarization profiles are independently generated in transmission under different incident handedness, which can then be converted into two distinct intensity profiles for demonstrating spin‐controlled grayscale images with 8 bit pixel depth. The proposed chiral grayscale imaging approach with subwavelength spatial resolution and high data density provides a versatile platform for many future applications in image encryption and decryption, dynamic display, advanced chiroptical sensing, and optical information processing.
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3D Janus plasmonic helical nanoapertures for polarization-encrypted data storage
Abstract Helical structures have attracted considerable attention due to their inherent optical chirality. Here, we report a unique type of 3D Janus plasmonic helical nanoaperture with direction-controlled polarization sensitivity, which is simply fabricated via the one-step grayscale focused ion beam milling method. Circular dichroism in transmission of as large as 0.72 is experimentally realized in the forward direction due to the spin-dependent mode coupling process inside the helical nanoaperture. However, in the backward direction, the nanoaperture acquires giant linear dichroism in transmission of up to 0.87. By encoding the Janus metasurface with the two nanoaperture enantiomers having specified rotation angles, direction-controlled polarization-encrypted data storage is demonstrated for the first time, where a binary quick-response code image is displayed in the forward direction under the circularly polarized incidence of a specified handedness, while a distinct grayscale image is revealed in the backward direction under linearly polarized illumination with a specified azimuthal angle. We envision that the proposed Janus helical nanoapertures will provide an appealing platform for a variety of applications, which will range from multifunctional polarization control, enantiomer sensing, data encryption and decryption to optical information processing.
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- PAR ID:
- 10150136
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Light: Science & Applications
- Volume:
- 8
- Issue:
- 1
- ISSN:
- 2047-7538
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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