title: Ultrasmall all-optical plasmonic switch and its application to superresolution imaging.
abstract: Because of their exceptional local-field enhancement and ultrasmall mode volume, plasmonic components can integrate photonics and electronics at nanoscale, and active control of plasmons is the key. However, all-optical modulation of plasmonic response with nanometer mode volume and unity modulation depth is still lacking. Here we show that scattering from a plasmonic nanoparticle, whose volume is smaller than 0.001 μm(3), can be optically switched off with less than 100 μW power. Over 80% modulation depth is observed, and shows no degradation after repetitive switching. The spectral bandwidth approaches 100 nm. The underlying mechanism is suggested to be photothermal effects, and the effective single-particle nonlinearity reaches nearly 10(-9) m(2)/W, which is to our knowledge the largest record of metallic materials to date. As a novel application, the non-bleaching and unlimitedly switchable scattering is used to enhance optical resolution to λ/5 (λ/9 after deconvolution), with 100-fold less intensity requirement compared to similar superresolution techniques. Our work not only opens up a new field of ultrasmall all-optical control based on scattering from a single nanoparticle, but also facilitates superresolution imaging for long-term observation.
authors.affiliation: Department of Physics, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan.
authors.forename: Hsueh-Yu
authors.initials: HY
authors.lastname: Wu
authors.affiliation: Department of Physics, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan.
authors.forename: Yen-Ta
authors.initials: YT
authors.lastname: Huang
authors.affiliation: Department of Physics, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan.
authors.forename: Po-Ting
authors.initials: PT
authors.lastname: Shen
authors.affiliation: Department of Physics, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan.
authors.forename: Hsuan
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0851, Japan.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Oketani
authors.affiliation: Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0851, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Yonemaru
authors.affiliation: Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0851, Japan.
authors.forename: Masahito
authors.initials: M
authors.lastname: Yamanaka
authors.affiliation: Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0851, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Shoji
authors.affiliation: Institute of Physics, Academia Sinica, 128 Sec. 2, Academia Rd., Nankang, Taipei 11529, Taiwan.
authors.forename: Kung-Hsuan
authors.initials: KH
authors.lastname: Lin
authors.affiliation: Center for Condensed Matter Sciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan.
authors.forename: Chih-Wei
authors.initials: CW
authors.lastname: Chang
authors.affiliation: Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0851, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kawata
authors.affiliation: Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0851, Japan.
authors.forename: Katsumasa
authors.initials: K
authors.lastname: Fujita
authors.affiliation: Department of Physics, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan.|Molecular Imaging Center, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan.
authors.forename: Shi-Wei
authors.initials: SW
authors.lastname: Chu