title: Switching terahertz waves with gate-controlled active graphene metamaterials.
abstract: The extraordinary electronic properties of graphene provided the main thrusts for the rapid advance of graphene electronics. In photonics, the gate-controllable electronic properties of graphene provide a route to efficiently manipulate the interaction of photons with graphene, which has recently sparked keen interest in graphene plasmonics. However, the electro-optic tuning capability of unpatterned graphene alone is still not strong enough for practical optoelectronic applications owing to its non-resonant Drude-like behaviour. Here, we demonstrate that substantial gate-induced persistent switching and linear modulation of terahertz waves can be achieved in a two-dimensional metamaterial, into which an atomically thin, gated two-dimensional graphene layer is integrated. The gate-controllable light-matter interaction in the graphene layer can be greatly enhanced by the strong resonances of the metamaterial. Although the thickness of the embedded single-layer graphene is more than six orders of magnitude smaller than the wavelength (<λ/1,000,000), the one-atom-thick layer, in conjunction with the metamaterial, can modulate both the amplitude of the transmitted wave by up to 47% and its phase by 32.2° at room temperature. More interestingly, the gate-controlled active graphene metamaterials show hysteretic behaviour in the transmission of terahertz waves, which is indicative of persistent photonic memory effects.
authors.affiliation: Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-751, Republic of Korea.
authors.forename: Seung Hoon
authors.initials: SH
authors.lastname: Lee
authors.forename: Muhan
authors.initials: M
authors.lastname: Choi
authors.forename: Teun-Teun
authors.initials: TT
authors.lastname: Kim
authors.forename: Seungwoo
authors.initials: S
authors.lastname: Lee
authors.forename: Ming
authors.initials: M
authors.lastname: Liu
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Yin
authors.forename: Hong Kyw
authors.initials: HK
authors.lastname: Choi
authors.forename: Seung S
authors.initials: SS
authors.lastname: Lee
authors.forename: Choon-Gi
authors.initials: CG
authors.lastname: Choi
authors.forename: Sung-Yool
authors.initials: SY
authors.lastname: Choi
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhang
authors.forename: Bumki
authors.initials: B
authors.lastname: Min