期刊
NANO LETTERS
卷 14, 期 8, 页码 4529-4534出版社
AMER CHEMICAL SOC
DOI: 10.1021/nl501558t
关键词
Surface plasmon; semiconductor; pump-probe; ultrafast spectroscopy; near-field microscopy; s-SNOM
类别
资金
- ONR
- AFOSR
- DOE-BES [DE-FG03-00ER45799]
- Alexander von Humboldt foundation
- Multidisciplinary University Research Initiative from the Air Force Office of Scientific Research (AFOSR MURI) [FA9550-12-1-0488]
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 photo-modulation 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 mu J/cm(2), much smaller than fluences of similar to 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 mu m 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.
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