Quantitative angle-resolved small-spot reflectance measurements on plasmonic perfect absorbers: Impedance matching and disorder effects

Andreas Tittl, Moshe G. Harats, Ramon Walter, Xinghui Yin, Martin Schäferling, Na Liu, Ronen Rapaport, Harald Giessen

Research output: Contribution to journalArticlepeer-review

78 Scopus citations

Abstract

Plasmonic devices with absorbance close to unity have emerged as essential building blocks for a multitude of technological applications ranging from trace gas detection to infrared imaging. A crucial requirement for such elements is the angle independence of the absorptive performance. In this work, we develop theoretically and verify experimentally a quantitative model for the angular behavior of plasmonic perfect absorber structures based on an optical impedance matching picture. To achieve this, we utilize a simple and elegant k-space measurement technique to record quantitative angle-resolved reflectance measurements on various perfect absorber structures. Particularly, this method allows quantitative reflectance measurements on samples where only small areas have been nanostructured, for example, by electron-beam lithography. Combining these results with extensive numerical modeling, we find that matching of both the real and imaginary parts of the optical impedance is crucial to obtain perfect absorption over a large angular range. Furthermore, we successfully apply our model to the angular dispersion of perfect absorber geometries with disordered plasmonic elements as a favorable alternative to current array-based designs.

Original languageEnglish
Pages (from-to)10885-10892
Number of pages8
JournalACS Nano
Volume8
Issue number10
DOIs
StatePublished - 28 Oct 2014
Externally publishedYes

Keywords

  • angular dispersion
  • impedance matching
  • perfect absorbers
  • plasmonics

ASJC Scopus subject areas

  • Materials Science (all)
  • Engineering (all)
  • Physics and Astronomy (all)

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