Spin-controlled directional launching of surface plasmons at the subwavelength scale
Huang Tao1, Wang Jia-jian2, Li Zi-wei2, Liu Wei1, Lin Feng1, Fang Zhe-yu1, 3, Zhu Xing1, 4, †,
       

(a) Schematic diagram of the defined curve above. The inclined dashed line in point A stands for the tangent line at A.