Applied Physics B

, 122:94

Investigation of the nonlinear refractive index of single-crystalline thin gold films and plasmonic nanostructures

  • Sebastian Goetz
  • Gary Razinskas
  • Enno Krauss
  • Christian Dreher
  • Matthias Wurdack
  • Peter Geisler
  • Monika Pawłowska
  • Bert Hecht
  • Tobias Brixner
Article

DOI: 10.1007/s00340-016-6370-7

Cite this article as:
Goetz, S., Razinskas, G., Krauss, E. et al. Appl. Phys. B (2016) 122: 94. doi:10.1007/s00340-016-6370-7
Part of the following topical collections:
  1. Ultrafast Nanooptics

Abstract

The nonlinear refractive index of plasmonic materials may be used to obtain nonlinear functionality, e.g., power-dependent switching. Here, we investigate the nonlinear refractive index of single-crystalline gold in thin layers and nanostructures on dielectric substrates. In a first step, we implement a z-scan setup to investigate ~100-µm-sized thin-film samples. We determine the nonlinear refractive index of fused silica, n2(SiO2) = 2.9 × 10−20 m2/W, in agreement with literature values. Subsequent z-scan measurements of single-crystalline gold films reveal a damage threshold of 0.22 TW/cm2 and approximate upper limits of the real and imaginary parts of the nonlinear refractive index, |n2′(Au)| < 1.2 × 10−16 m2/W and |n2″(Au)| < 0.6 × 10−16 m2/W, respectively. To further determine possible effects of a nonlinear refractive index in plasmonic circuitry, interferometry is proposed as a phase-sensitive probe. In corresponding nanostructures, relative phase changes between two propagating near-field modes are converted to amplitude changes by mode interference. Power-dependent experiments using sub-10-fs near-infrared pulses and diffraction-limited resolution (NA = 1.4) reveal linear behavior up to the damage threshold (0.23 times relative to that of a solid single-crystalline gold film). An upper limit for the nonlinear power-dependent phase change between two propagating near-field modes is determined to Δφ < 0.07 rad.

Funding information

Funder NameGrant NumberFunding Note
Deutsche Forschungsgemeinschaft
  • SPP 1391
  • SPP 1391

Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Sebastian Goetz
    • 1
  • Gary Razinskas
    • 2
  • Enno Krauss
    • 2
  • Christian Dreher
    • 1
  • Matthias Wurdack
    • 1
  • Peter Geisler
    • 2
  • Monika Pawłowska
    • 1
    • 3
  • Bert Hecht
    • 2
    • 4
  • Tobias Brixner
    • 1
    • 4
  1. 1.Institut für Physikalische und Theoretische ChemieUniversität WürzburgWürzburgGermany
  2. 2.Nano-Optics and Biophotonics Group, Experimentelle Physik 5Universität WürzburgWürzburgGermany
  3. 3.Nencki Institute for Experimental BiologyPolish Academy of SciencesWarsawPoland
  4. 4.Röntgen Research Center for Complex Material Systems (RCCM)Universität WürzburgWürzburgGermany

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