title: Monolayer graphene sensing enabled by the strong Fano-resonant metasurface.
abstract: Recent advances in graphene photonics reveal promising applications in the technologically important terahertz spectrum, where graphene-based active terahertz metamaterial modulators have been experimentally demonstrated. However, the sensitivity of the atomically thin graphene monolayer towards sharp Fano resonant terahertz metasurfaces remains unexplored. Here, we demonstrate thin-film sensing of the graphene monolayer with a high quality factor terahertz Fano resonance in metasurfaces consisting of a two-dimensional array of asymmetric resonators. A drastic change in the transmission amplitude of the Fano resonance was observed due to strong interactions between the monolayer graphene and the tightly confined electric fields in the capacitive gaps of the Fano resonator. The deep-subwavelength sensing of the atomically thin monolayer graphene further highlights the extreme sensitivity of the resonant electric field excited at the dark Fano resonance, allowing the detection of an analyte that is λ/1 000 000 thinner than the free space wavelength.
authors.affiliation: Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University and the Key Laboratory of Optoelectronics Information and Technology (Ministry of Education), Tianjin 300072, China. tianzhen@tju.edu.cn jiaghan@tju.edu.cn and School of Electronic Engineering, Tianjin University of Technology and Education, Tianjin 300222, China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Li
authors.affiliation: Division of Physics and Applied Physics, Center for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link 637371, Singapore. ranjans@ntu.edu.sg.
authors.forename: Longqing
authors.initials: L
authors.lastname: Cong
authors.affiliation: Division of Physics and Applied Physics, Center for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link 637371, Singapore. ranjans@ntu.edu.sg.
authors.forename: Ranjan
authors.initials: R
authors.lastname: Singh
authors.affiliation: School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, Oklahoma 74078, USA.
authors.forename: Ningning
authors.initials: N
authors.lastname: Xu
authors.affiliation: School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, Oklahoma 74078, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Cao
authors.affiliation: Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University and the Key Laboratory of Optoelectronics Information and Technology (Ministry of Education), Tianjin 300072, China. tianzhen@tju.edu.cn jiaghan@tju.edu.cn.
authors.forename: Xueqian
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University and the Key Laboratory of Optoelectronics Information and Technology (Ministry of Education), Tianjin 300072, China. tianzhen@tju.edu.cn jiaghan@tju.edu.cn.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Tian
authors.affiliation: Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University and the Key Laboratory of Optoelectronics Information and Technology (Ministry of Education), Tianjin 300072, China. tianzhen@tju.edu.cn jiaghan@tju.edu.cn and College of Electrical Engineering and Automation, Guilin University of Electronic Technology, Guilin 541000, China.
authors.forename: Liangliang
authors.initials: L
authors.lastname: Du
authors.affiliation: Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University and the Key Laboratory of Optoelectronics Information and Technology (Ministry of Education), Tianjin 300072, China. tianzhen@tju.edu.cn jiaghan@tju.edu.cn.
authors.forename: Jiaguang
authors.initials: J
authors.lastname: Han
authors.affiliation: Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University and the Key Laboratory of Optoelectronics Information and Technology (Ministry of Education), Tianjin 300072, China. tianzhen@tju.edu.cn jiaghan@tju.edu.cn and School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, Oklahoma 74078, USA.
authors.forename: Weili
authors.initials: W
authors.lastname: Zhang