title: Tunable subwavelength hot spot of dipole nanostructure based on VO2 phase transition.
abstract: We propose a novel approach to generate and tune a hot spot in a dipole nanostructure of vanadium dioxide (VO2) laid on a gold (Au) substrate. By inducing a phase transition of the VO2, the spatial and spectral distributions of the hot spot generated in the feed gap of the dipole can be tuned. Our numerical simulation based on a finite-element method shows a strong intensity enhancement difference and tunability near the wavelength of 678 nm, where the hot spot shows 172-fold intensity enhancement when VO2 is in the semiconductor phase. The physical mechanisms of forming the hot spots at the two-different phases are discussed. Based on our analysis, the effects of geometric parameters in our dipole structure are investigated with an aim of enhancing the intensity and the tunability. We hope that the proposed nanostructure opens up a practical approach for the tunable near-field nano-photonic devices.
authors.affiliation: National Creative Research Center for Active Plasmonics Application Systems Inter-University SemiconductorResearch Center and School of Electrical Engineering Seoul National University, Gwanak-Gu Gwanakro 1, Seoul151-744, South Korea.
authors.forename: Jun-Bum
authors.initials: JB
authors.lastname: Park
authors.forename: Il-Min
authors.initials: IM
authors.lastname: Lee
authors.forename: Seung-Yeol
authors.initials: SY
authors.lastname: Lee
authors.forename: Kyuho
authors.initials: K
authors.lastname: Kim
authors.forename: Dawoon
authors.initials: D
authors.lastname: Choi
authors.forename: Eui Young
authors.initials: EY
authors.lastname: Song
authors.forename: Byoungho
authors.initials: B
authors.lastname: Lee