title: Observation of Plasmon Wave Packet Motions via Femtosecond Time-Resolved Near-Field Imaging Techniques.
abstract: The generation and dynamics of plasmon wave packets in single gold nanorods were observed at a spatiotemporal scale of 100 nm and 10 fs via time-resolved near-field optical microscopy. Following simultaneous excitation of two plasmon modes of a nanorod with an ultrashort near-field pulse, a decay and revival feature of the time-resolved signal was obtained, which reflected the reciprocating motion of the wave packet. The time-resolved near-field images were also indicative of the wave packet motion. At some period of time after the excitation, the spatial features of the two modes appeared alternately, showing motion of plasmonic wave crests along the rod. The wave packet propagation was clearly demonstrated from this observation with the aid of a simulation model. The present experimental scheme opens the door to coherent control of plasmon-induced optical fields in a nanometer spatial scale and femtosecond temporal scale.
authors.affiliation: Institute for Molecular Science , Myodaiji, 38 Nishigonaka, Okazaki, Aichi 444-8585, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Nishiyama
authors.affiliation: School of Advanced Science and Engineering, Waseda University , Okubo, Shinjuku, Tokyo 169-8555, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Imura
authors.affiliation: Institute for Molecular Science , Myodaiji, 38 Nishigonaka, Okazaki, Aichi 444-8585, Japan.|The Graduate University for Advanced Studies , Myodaiji, 38 Nishigonaka, Okazaki, Aichi 444-8585, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Okamoto
keywords: Plasmon wave packet; nanoscale; near-field optical microscopy; ultrafast dynamics