Ultrathin Planar Cavity Metasurfaces |
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| Authors: | Hsiang‐Chu Wang Cheng Hung Chu Pin Chieh Wu Hui‐Hsin Hsiao Hui Jun Wu Jia‐Wern Chen Wei Hou Lee Yi‐Chieh Lai Yao‐Wei Huang Ming Lun Tseng Shu‐Wei Chang Din Ping Tsai |
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| Affiliation: | 1. Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan;2. Department of Physics, National Taiwan University, Taipei, Taiwan;3. Graduate Institute of Biomedical Optomechatronics, Taipei Medical University, Taipei, Taiwan |
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| Abstract: | An ultrathin planar cavity metasurface is proposed based on ultrathin film interference and its practicability for light manipulation in visible region is experimentally demonstrated. Phase of reflected light is modulated by finely adjusting the thickness of amorphous silicon (a‐Si) by a few nanometers on an aluminum (Al) substrate via nontrivial phase shifts at the interfaces and interference of multireflections generated from the planar cavity. A phase shift of π, the basic requirement for two‐level phase metasurface systems, can be accomplished with an 8 nm thick difference. For proof of concept, gradient metasurfaces for beam deflection, Fresnel zone plate metalens for light focusing, and metaholograms for image reconstruction are presented, demonstrating polarization‐independent and broadband characteristics. This novel mechanism for phase modulation with ultrathin planar cavity provides diverse routes to construct advanced flat optical devices with versatile applications. |
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| Keywords: | beam deflection Fresnel zone plates metaholograms metasurfaces ultrathin planar cavities |
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