Polarization-insensitive unidirectional spoof surface plasmon polaritons coupling by gradient metasurface
Shi Hong-yu1, Zhang An-xue1, 2, †, , Chen Jian-zhong1, Wang Jia-fu3, Xia Song4, Xu Zhuo4
       

The simulated dispersion curves of the resonators with different geometric parameter l. k is the wave number of the excitation and p is the period of the resonators.