Tan Zhiyu, Fan Fei, Dong Xipu, Cheng Jierong, Chang Shengjiang
Institute of Modern Optics, Nankai University, Tianjin, 300350, China.
Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Tianjin, 300350, China.
Sci Rep. 2019 Dec 27;9(1):20210. doi: 10.1038/s41598-019-56789-x.
In this work, an active nonreciprocal THz beam steering has been proposed based on a transversely magnetized metal/InSb metagrating. The nonreciprocal dispersion relation and phase shift characteristics of the metal/InSb waveguide are investigated in details. A metagrating structure with gradient phase shift has been designed based on the metal/InSb waveguide. Under the external magnetic field (EMF), the THz beam can be changed among 0, +1, and -1 order of the metagrating. Due to the nonreciprocity of the metal/InSb metagrating, the deflection angle can be controlled by changing the positive and negative directions of the EMF, to realize bilateral symmetric scanning from -67.8° to 67.8° with over 70% diffraction efficiency, and this device also exhibits the nonreciprocal one-way transmission as an isolator with the isolation of 13 dB. This low-loss, large deflection degree, nonreciprocal beam scanner has a great potential application in the THz regime.
在这项工作中，基于横向磁化的金属/锑化铟超颖光栅提出了一种有源非互易太赫兹波束转向方法。详细研究了金属/锑化铟波导的非互易色散关系和相移特性。基于金属/锑化铟波导设计了一种具有梯度相移的超颖光栅结构。在外加磁场（EMF）作用下，太赫兹波束可以在超颖光栅的0、+1和-1级之间切换。由于金属/锑化铟超颖光栅的非互易性，可以通过改变外加磁场的正负方向来控制偏转角，实现-67.8°至67.8°的双侧对称扫描，衍射效率超过70%，并且该器件还表现出作为隔离器的非互易单向传输特性，隔离度为13 dB。这种低损耗、大偏转角的非互易波束扫描器在太赫兹领域具有巨大的潜在应用价值。
