title: Ultrafast imaging of surface plasmons propagating on a gold surface.
abstract: We record time-resolved nonlinear photoemission electron microscopy (tr-PEEM) images of propagating surface plasmons (PSPs) launched from a lithographically patterned rectangular trench on a flat gold surface. Our tr-PEEM scheme involves a pair of identical, spatially separated, and interferometrically locked femtosecond laser pulses. Power-dependent PEEM images provide experimental evidence for a sequential coherent nonlinear photoemission process, in which one laser source launches a PSP through a linear interaction, and the second subsequently probes the PSP via two-photon photoemission. The recorded time-resolved movies of a PSP allow us to directly measure various properties of the surface-bound wave packet, including its carrier wavelength (783 nm) and group velocity (0.95c). In addition, tr-PEEM images reveal that the launched PSP may be detected at least 250 μm away from the coupling trench structure.
authors.affiliation: †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
authors.forename: Yu
authors.initials: Y
authors.lastname: Gong
authors.affiliation: †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
authors.forename: Alan G
authors.initials: AG
authors.lastname: Joly
authors.affiliation: †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
authors.forename: Dehong
authors.initials: D
authors.lastname: Hu
authors.affiliation: †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
authors.forename: Patrick Z
authors.initials: PZ
authors.lastname: El-Khoury
authors.affiliation: †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States.
authors.forename: Wayne P
authors.initials: WP
authors.lastname: Hess
keywords: PEEM; Propagating surface plasmon; sub-femtosecond; time-resolved