Materials with tunable negative index of refraction and reduced absorption

• Applicant: Professor Dr. Michael Fleischhauer
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2007 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 47366906

• Final Report Year: 2012

Final Report Abstract

A novel approach to achieve a negative index of refraction in near-resonant atomic systems or other quantum oscillators with simulatenously strongly suppressed absorption was proposed and theoretically analyzed. In the proposal coherent cross coupling between nearly degenerate electric and magnetic dipole transitions e.g. by laser fields resulted in a chiral cross-coupling between electric and magnetic compents of a probe field. Interference phenomena similar to electromagnetically induced transparency caused resonant amplification of chiral cross coupling and simultaneously lead to a suppressed electric response, which is the main source of absorption losses. The effect termed electromagnetically induced chirality lead to theoretical values for the achievable ratio of negative refraction to absorption of 100 and larger, which exceeds by far state-of-the-art values, which are on the order of unity. The initially scalar, one-dimensional theory was generalized to three dimension and the tensorial properties of the medium were investigated. Furthermore local field corrections in dense media were analyzed, which required to generalize existing theories of local field effects from purely dielectric to magneto-electric media. In collaboration with the experimental group of H. Giessen (Stuttgart) the first successful demonstration of interference effects like electromagnetically induced transparency in nano-plasmonic structures was performed. This opens new ways to apply concepts of atomic physics to solid-state meta-materials and was highlighted in several media (“Plasmonics: The benefits of darkness“, Nature News, Nature Materials 8, (2009) ; “Durchsichtige Goldpartikel”, Stuttgarter Zeitung, 07. July 2009; “Plasmonic transparency”, research highlights of Nature Physics, Vol. 5, August 2009).

Publications

• Comment on: ”Electromagnetically induced left-handedness in optically excited four-level atomic media”. Phys. Rev. Lett 98, 069301 (2007)
  J. Kästel, M. Fleischhauer
  
• Local-field effects in radiatively broadened magneto-dielectric media: negative refraction and absorption reduction. Phys. Rev. A 76, 062509 (2007)
  J. Kästel, M. Fleischhauer, G. Juzeliunas
  
• Tunable negative refraction without absorption in the optical regime. Phys. Rev. Lett. 99, 073602 (2007)
  J. Kästel, M. Fleischhauer, S. F. Yelin, R. L. Walsworth
  
• Ph.D. Thesis, University of Kaiserslautern (2008). Quantum interference and absorption suppression in negative index materials
  Jürgen Kästel
  
• Low-loss negative refraction by laser induced magneto-electric cross-coupling. Phys. Rev. A 79, 063818 (2009)
  J. Kästel, M. Fleischhauer, S. F. Yelin, R. L. Walsworth
  
• Plasmonic analogue of electromagnetically induced transparency at the Drude damping limit. Nature Materials 8, 758 (2009)
  Na Liu, Lutz Langguth, Thomas Weiss, Juergen Kästel, Michael Fleischhauer, Tilman Pfau and Harald Giesen