Opto-Electronic Engineering, Volume. 44, Issue 3, 331(2017)
Two dimensional subdiffraction focusing beyond the near-field diffraction limit via metasurface
Near-field plates with the capabilities of modulating the near-field pattern and forcing the incident wave to a subwavelength spot have been experimentally investigated at microwave wavelengths. Their super-lensing properties result from the radiationless electromagnetic interference. However, the material’s loss and limitations of state-of-the-art nanofabricating technology pose great challenges to scale down the microwave near-field plates to the infrared or optical region. In this paper, a related but alternative approach based on metasurface is introduced which breaks the near-field diffraction limit at mid-infrared region (10.6 μm). The metasurface consists of periodic arrangement of chromium dipolar antennas with the same geometry but spa-tially varying orientations, which plays the dual roles in achieving the prescribed amplitude modulation and the abrupt π phase change between the subwavelength neighboring elements. As a result, a two dimensional sub-diffraction focus as small as 0.037λ2 at ~0.15λ above the metasurface is presented. In addition, the broadband response and ease fabrication bridge the gap between the theoretical investigation and valuable applications, such as near-field data storage, subdiffraction imaging and nanolithography.
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[in Chinese], [in Chinese]. Two dimensional subdiffraction focusing beyond the near-field diffraction limit via metasurface[J]. Opto-Electronic Engineering, 2017, 44(3): 331
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Received: Nov. 17, 2016
Accepted: --
Published Online: Jun. 6, 2017
The Author Email: (hlyu@cqu.edu.cn)