title: Ultrafast dynamics of surface plasmons in InAs by time-resolved infrared nanospectroscopy.
abstract: We report on time-resolved mid-infrared (mid-IR) near-field spectroscopy of the narrow bandgap semiconductor InAs. The dominant effect we observed pertains to the dynamics of photoexcited carriers and associated surface plasmons. A novel combination of pump-probe techniques and near-field nanospectroscopy accesses high momentum plasmons and demonstrates efficient, subpicosecond photomodulation of the surface plasmon dispersion with subsequent tens of picoseconds decay under ambient conditions. The photoinduced change of the probe intensity due to plasmons in InAs is found to exceed that of other mid-IR or near-IR media by 1-2 orders of magnitude. Remarkably, the required control pulse fluence is as low as 60 μJ/cm(2), much smaller than fluences of ∼ 1-10 mJ/cm(2) previously utilized in ultrafast control of near-IR plasmonics. These low excitation densities are easily attained with a standard 1.56 μm fiber laser. Thus, InAs--a common semiconductor with favorable plasmonic properties such as a low effective mass--has the potential to become an important building block of optically controlled plasmonic devices operating at infrared frequencies.
authors.affiliation: Department of Physics, University of California, San Diego , La Jolla, California 92093, United States.
authors.forename: Martin
authors.initials: M
authors.lastname: Wagner
authors.forename: Alexander S
authors.initials: AS
authors.lastname: McLeod
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Maddox
authors.forename: Zhe
authors.initials: Z
authors.lastname: Fei
authors.forename: Mengkun
authors.initials: M
authors.lastname: Liu
authors.forename: Richard D
authors.initials: RD
authors.lastname: Averitt
authors.forename: Michael M
authors.initials: MM
authors.lastname: Fogler
authors.forename: Seth R
authors.initials: SR
authors.lastname: Bank
authors.forename: Fritz
authors.initials: F
authors.lastname: Keilmann
authors.forename: D N
authors.initials: DN
authors.lastname: Basov