\begin{document}$\kappa $\end{document} and completely control the direction of outing wave. Therefore, the metasurface can possess many novel optical applications, such as holograms, metalenses, photonic spin Hall effect, etc. In this work, we design a simplified reflection-type optical metagrating. The results demonstrate that the metagrating can achive the function of two-channel retroreflection, that is, redirecting the incident wave back toward the source, with a nearly perfect conversion efficiency.The metagrating designed in this paper contains only two sub-cells with π reflection phase difference in period. The working wavelength (λ) of metagrating is fixed at 3 μm. The two sub-cells are filled with an impedance matching material (their material relative refractive indexes are n1 = 1 and n2 = 1.5 respectively and their thickness is d = 1.5 μm.).The period length range is 1.5 μm ≤ p ≤ 3 μm(considering reducing the reflection order). When the incident angle is \begin{document}${\theta _{\rm{i}}}= \pm \arcsin [\lambda /(2p)]$\end{document}, the absolute values of the incident angle and the reflected angle are equal, and then retroreflection occurs. When the wavelength is greater than the period (\begin{document}$\lambda \geqslant p$\end{document}), the angle of retroreflection can be adjusted to any value (\begin{document}$\left| {{\theta _{\rm{i}}}} \right| \geqslant {\rm{3}}{{\rm{0}}^ \circ }$\end{document}) by adjusting the period p. In this work, COMSOL MULTIPHYSICS software is used to simulate the retroreflection reflectivity and field pattern of the designed metagrating. The results verify the two-channel retroreflection property of the metagrating. In addition,as the angle of incidence changes from 30° to 60°, the efficiency of retroreflection at any incident angle can reach to more than 95%. When the incident angle is 75.4°, the metagrating still has an efficiency of 80% retroreflection. Therefore, the metagrating also achieves the function of high-efficiency retroreflection at a large-angle. Comparing with multiple sub-cells’ metasurface, the simplified metagrating with two sub-cells enables a similar function of retroreflection, but has many potential advantages, and can play an important role in high-efficiency sensing, imaging and communication."> - 必威体育下载

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    Wang Mei-Ou, Xiao Qian, Jin Xia, Cao Yan-Yan, Xu Ya-Dong
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    • Abstract views:8466
    • PDF Downloads:179
    • Cited By:0
    Publishing process
    • Received Date:26 July 2019
    • Accepted Date:03 October 2019
    • Available Online:07 December 2019
    • Published Online:05 January 2020

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