title: Efficient unidirectional launching of surface plasmons by a cascade asymmetric-groove structure.
abstract: Increasing the unidirectional launching efficiency of surface plasmon polaritons (SPPs) is crucial in plasmonics. Here, we demonstrate that this efficiency may be improved by cascading subwavelength unidirectional SPP launching units. A unidirectional SPP launching efficiency of at least 46% and an extinction ratio of 40 are experimentally demonstrated using a cascade asymmetric-groove structure. Meanwhile, the device is ultracompact, and has a lateral dimension of only 1.1 μm. The proposed structure also presents a broadband response and is easy to fabricate. This high-performance wavelength-scale unidirectional SPP launcher represents an important development in practical SPP sources.
authors.affiliation: School of Physics, Peking University, Beijing 100871, China. HMLiao@pku.edu.cn z_li@pku.edu.cn.
authors.forename: Xue-Yang
authors.initials: XY
authors.lastname: Song
authors.affiliation: School of Physics, Peking University, Beijing 100871, China. HMLiao@pku.edu.cn z_li@pku.edu.cn.
authors.forename: Zhengxing
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: School of Physics, Peking University, Beijing 100871, China. HMLiao@pku.edu.cn z_li@pku.edu.cn.
authors.forename: Huimin
authors.initials: H
authors.lastname: Liao
authors.affiliation: School of Physics, Peking University, Beijing 100871, China. HMLiao@pku.edu.cn z_li@pku.edu.cn.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Li
authors.affiliation: School of Physics, Peking University, Beijing 100871, China. HMLiao@pku.edu.cn z_li@pku.edu.cn and State Key Laboratory for Mesoscopic Physics, Peking University, Beijing 100871, China.
authors.forename: Chengwei
authors.initials: C
authors.lastname: Sun
authors.affiliation: School of Physics, Peking University, Beijing 100871, China. HMLiao@pku.edu.cn z_li@pku.edu.cn and State Key Laboratory for Mesoscopic Physics, Peking University, Beijing 100871, China.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Chen
authors.affiliation: School of Physics, Peking University, Beijing 100871, China. HMLiao@pku.edu.cn z_li@pku.edu.cn and State Key Laboratory for Mesoscopic Physics, Peking University, Beijing 100871, China.
authors.forename: Qihuang
authors.initials: Q
authors.lastname: Gong