Experimental determination of the refractive index of metamaterials

Michael G. Nielsen, Anders Pors, Ole Albrektsen, Morten Willatzen, Sergey I. Bozhevolnyi

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

We present a simple experimental technique based on diffraction for determining the complex refractive index of metamaterials, and demonstrate it with metamaterials that consist of detuned electrical dipoles (DEDs), mimicking the dressed-state picture of electromagnetically induced transparency (EIT). The metamaterials are realized by fabricating lithographically defined gold nanorods on a silica substrate, covered with a similar to 15 mu m thick polymer layer, and feature EIT-like transmission spectra with transparency windows centered at wavelengths near similar to 800 nm. The refractive indices are determined for wavelengths where the DED metamaterials exhibit enhanced transmission. Thereby, we experimentally demonstrate normal dispersion in the transmission window and estimate the group refractive index to similar to 3.6. Furthermore, finite-element simulations are conducted on a monolayer of DED unit cells, which similarly exhibit the EIT-like behavior in terms of enhanced transmission revealed in the transmission spectra. Simulated transmission and reflection spectra are utilized for calculations of the real and imaginary parts of the metamaterial refractive index, showing consistent trends with those obtained experimentally.
Original languageEnglish
JournalJournal of Optics
Volume13
Issue number5
Pages (from-to)055106
Number of pages7
ISSN2040-8978
DOIs
Publication statusPublished - 2011
Externally publishedYes

Keywords

  • Electromagnetically induced transparancy
  • Optics
  • Light
  • Limit

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