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Wang HC, Chu CH, Wu PC, Hsiao HH, Wu HJ, Chen JW, Lee WH, Lai YC, Huang YW, Tseng ML, Chang SW, Tsai DP. Ultrathin Planar Cavity Metasurfaces. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1703920. [PMID: 29611338 DOI: 10.1002/smll.201703920] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 01/19/2018] [Indexed: 06/08/2023]
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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Affiliation(s)
- Hsiang-Chu Wang
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Cheng Hung Chu
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Pin Chieh Wu
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Hui-Hsin Hsiao
- Graduate Institute of Biomedical Optomechatronics, Taipei Medical University, Taipei, 11031, Taiwan
| | - Hui Jun Wu
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Jia-Wern Chen
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Wei Hou Lee
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Yi-Chieh Lai
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - Yao-Wei Huang
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Ming Lun Tseng
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Shu-Wei Chang
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Din Ping Tsai
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
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Abstract
Manipulation of nanoparticles in solution is of great importance for a wide range of applications in biomedical, environmental, and material sciences. In this work, we present a novel plasmonic tweezers based on metahologram. We show that various kinds of nanoparticles can be stably trapped in a surface plasmon (SP) standing wave generated by the constructive interference between two coherent focusing SPs. The absence of the axial scattering force and the enhanced gradient force enable to avoid overheating effect while maintaining mechanical stability even under the resonant condition of the metallic nanoparticle. The work illustrates the potential of such plasmonic tweezers for further development in lab-on-a-chip devices.
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