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.
Y. Chen et al., "3D Janus Plasmonic Helical Nanoapertures for Polarization-Encrypted Data Storage," Light: Science and Applications, vol. 8, no. 1, Nature Publishing Group, Dec 2019.
The definitive version is available at https://doi.org/10.1038/s41377-019-0156-8
Mechanical and Aerospace Engineering
Intelligent Systems Center
Keywords and Phrases
Dichroism; Digital storage; Enantiomers; Ion beams; Optical data processing; Plasmonics; Plasmons; Polarization, Circularly polarized incidence; Controlled polarization; Focused ion beam milling methods; Helical structures; Linearly polarized; Optical chirality; Polarization control; Quick response code, Cryptography
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01 Dec 2019