title: Electromagnetic energy vortex associated with sub-wavelength plasmonic Taiji marks.
authors.affiliation: Department of Physics, National Taiwan University, Taipei, Taiwan.
authors.forename: Wei Ting
authors.initials: WT
authors.lastname: Chen
authors.forename: Pin Chieh
authors.initials: PC
authors.lastname: Wu
authors.forename: Chen Jung
authors.initials: CJ
authors.lastname: Chen
authors.forename: Hung-Yi
authors.initials: HY
authors.lastname: Chung
authors.forename: Yuan-Fong
authors.initials: YF
authors.lastname: Chau
authors.forename: Chieh-Hsiung
authors.initials: CH
authors.lastname: Kuan
authors.forename: Din Ping
authors.initials: DP
authors.lastname: Tsai