Enhancement of high harmonic generation by confining electron motion in plasmonic nanostrutures

M. F. Ciappina*, Srdjan S. Aćimović, T. Shaaran, J. Biegert, R. Quidant, M. Lewenstein

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

118 Scopus citations

Abstract

We study high-order harmonic generation (HHG) resulting from the illumination of plasmonic nanostructures with a short laser pulse of long wavelength. We demonstrate that both the confinement of the electron motion and the inhomogeneous character of the laser electric field play an important role in the HHG process and lead to a significant increase of the harmonic cutoff. In particular, in bow-tie nanostructures with small gaps, electron trajectories with large excursion amplitudes experience significant confinement and their contribution is essentially suppressed. In order to understand and characterize this feature, we combine the numerical solution of the time-dependent Schrödinger equation (TDSE) with the electric fields obtained from 3D finite element simulations. We employ time-frequency analysis to extract more detailed information from the TDSE results and classical tools to explain the extended harmonic spectra. The spatial inhomogeneity of the laser electric field modifies substantially the electron trajectories and contributes also to cutoff increase.

Original languageEnglish
Pages (from-to)26261-26274
Number of pages14
JournalOptics Express
Volume20
Issue number24
DOIs
StatePublished - 19 Nov 2012
Externally publishedYes

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