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Broadband and Robust Metalens with Nonlinear Phase Profiles for Efficient Terahertz Wave Control
Author(s) -
Yang Quanlong,
Gu Jianqiang,
Xu Yuehong,
Zhang Xueqian,
Li Yanfeng,
Ouyang Chunmei,
Tian Zhen,
Han Jiaguang,
Zhang Weili
Publication year - 2017
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.201601084
Subject(s) - terahertz radiation , optics , broadband , materials science , terahertz gap , optoelectronics , electromagnetic spectrum , transmittance , phase (matter) , electromagnetic radiation , terahertz spectroscopy and technology , terahertz metamaterials , physics , far infrared laser , laser , quantum mechanics
Metasurfaces, 2D artificial electromagnetic media, open up a new frontier of functional device design ranging from radio waves to the visible region. Particularly, metasurface‐based lenses are indispensable in various practical terahertz applications. The authors aim at achieving flexible and robust metalenses for efficient terahertz wave control. In general, resolution and efficiency are two inevitable parameters in determining the focusing and imaging abilities of lenses, which however are rarely experimentally demonstrated in the terahertz band. In this Communication, three broadband and robust metalenses with nonlinear phase profiles are proposed, all of which are experimentally investigated by using near‐field scanning terahertz microscopy (NSTM) with a spatial resolution of 50 µm. The measurement shows that the metalens can focus a 0.95 THz wave to a spot size of 580 µm and achieve a transmittance efficiency of 45%. In addition, the NSTM system facilitates an experimental investigation of the incidence angle dependence of the terahertz metalens, which proves the robust focusing feature of the proposed device. This demonstration delivers a promising metasurface design for potential applications in imaging and information processing that may be of interest for the entire electromagnetic spectrum.