title: Switchable Ultrathin Quarter-wave Plate in Terahertz Using Active Phase-change Metasurface.
abstract: Metamaterials open up various exotic means to control electromagnetic waves and among them polarization manipulations with metamaterials have attracted intense attention. As of today, static responses of resonators in metamaterials lead to a narrow-band and single-function operation. Extension of the working frequency relies on multilayer metamaterials or different unit cells, which hinder the development of ultra-compact optical systems. In this work, we demonstrate a switchable ultrathin terahertz quarter-wave plate by hybridizing a phase change material, vanadium dioxide (VO2), with a metasurface. Before the phase transition, VO2 behaves as a semiconductor and the metasurface operates as a quarter-wave plate at 0.468 THz. After the transition to metal phase, the quarter-wave plate operates at 0.502 THz. At the corresponding operating frequencies, the metasurface converts a linearly polarized light into a circularly polarized light. This work reveals the feasibility to realize tunable/active and extremely low-profile polarization manipulation devices in the terahertz regime through the incorporation of such phase-change metasurfaces, enabling novel applications of ultrathin terahertz meta-devices.
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.|Institute for Infocomm Research, 1 Fusionoplis Way, #21-01 Connexis, 138632, Singapore.
authors.forename: Dacheng
authors.initials: D
authors.lastname: Wang
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.|NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, 117411, Singapore.
authors.forename: Lingchao
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.
authors.forename: Yinghong
authors.initials: Y
authors.lastname: Gu
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.
authors.forename: M Q
authors.initials: MQ
authors.lastname: Mehmood
authors.affiliation: Institute for Infocomm Research, 1 Fusionoplis Way, #21-01 Connexis, 138632, Singapore.
authors.forename: Yandong
authors.initials: Y
authors.lastname: Gong
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.|NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, 117411, Singapore.
authors.forename: Amar
authors.initials: A
authors.lastname: Srivastava
authors.affiliation: NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, 117411, Singapore.
authors.forename: Linke
authors.initials: L
authors.lastname: Jian
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.|Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.|NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, 117411, Singapore.|Materials Science and Engineering and Integrative Science and Engineering, National University of Singapore, 117456, Singapore.
authors.forename: T
authors.initials: T
authors.lastname: Venkatesan
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.
authors.forename: Cheng-Wei
authors.initials: CW
authors.lastname: Qiu
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.
authors.forename: Minghui
authors.initials: M
authors.lastname: Hong