title: Tunable Wide-Angle Tunneling in Graphene-Assisted Frustrated Total Internal Reflection.
abstract: Electrically tunable permittivity of graphene provides an excellent tool in photonic device design. Many previous works on graphene-based photonic devices relied on variable absorption in graphene, which is naturally small in the optical region, and resonant structures to enhance it. Here we proposed a novel scheme to control evanescent coupling strength by inserting two graphene layers to a frustrated total internal reflection (FTIR) configuration. The resulting structure behaves in a drastically different way from the original FTIR: optical transmission though the structure can be electrically controlled from ~10(-5) to ~1 with little dependency on angle of incidence. This unique feature stems from the fact that the permittivity of doped graphene can be close to zero at a certain photon energy. The electrical controllability of evanescent coupling strength can enable novel design of optical devices. As a proof-of-concept, we designed a waveguide-type optical modulator of a novel operation principle: transmission modulation depends on the electrically controlled existence of a guided-mode of the waveguide, not the variation of the ohmic loss of graphene, resulting in a low insertion loss and a small device footprint.
authors.affiliation: Department of Electrical and Computer Engineering, Ajou University, Suwon, South Korea.
authors.forename: Thang Q
authors.initials: TQ
authors.lastname: Tran
authors.affiliation: Department of Energy System Research, Ajou University, Suwon 443-749, Korea.
authors.forename: Sangjun
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Electrical and Computer Engineering, Ajou University, Suwon, South Korea.
authors.forename: Hyungjun
authors.initials: H
authors.lastname: Heo
authors.affiliation: Department of Electrical and Computer Engineering, Ajou University, Suwon, South Korea.
authors.forename: Sangin
authors.initials: S
authors.lastname: Kim
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