• Hector Fellows

    Ausgezeichnete SpitzenforscherInnen aus den MINT-Fächern.

Current research projects

Tailored distributions of artificial materials called metamaterials allow for designing and fabricating invisibility cloaks in optics and counterparts thereof in other areas of physics. For example, cloaking can be used for making metal contact grids on solar cells invisible, thereby increasing the energy conversion efficiency by as much as 10% [1]. In the diffusive regime of light propagation, invisibility cloaking is also possible [2] and can, for example, be applied for homogenizing the light emission from large-area organic light-emitting diodes (OLED). The latter were inspired by thermal cloaks [3].

In a project of the Hector Fellow Academy jointly conducted with Hector Fellow Peter Gumbsch, mechanical metamaterials are being investigated. This has led to static mechanical cloaks [4,5] and to modified pentamode metamaterials [6] that might enable cloaks for mechanical waves in the future. Furthermore, tailored buckling nonlinear mechanical metamaterials can be designed that allow for large specific energy absorption – while being reusable. Metamaterials with tailored thermal expansion are another area of current research.

As another example for optical metamaterial, three-dimensional gold-helix architectures can be used as broadband circular polarizers [7]. Advanced versions thereof [8] take advantage of stimulated emission depletion (STED) laser lithography beyond the Abbe diffraction limit [9].

A more complete list of publications of the Wegener group can be found at http://www.aph.kit.edu/wegener/77.php

References

[1] Cloaked contact grids on solar cells by coordinate transformations: Designs and prototypes, M. Schumann, S. Wiesendanger, J.-C. Goldschmidt, B. Bläsi, K. Bittkau, U.W. Paetzold, A. Sprafke,
R. Wehrspohn, C. Rockstuhl, and M. Wegener, Optica 2, 850 (2015)

[2] Invisibility Cloaking in a Diffusive Light Scattering Medium, R. Schittny, M. Kadic, T. Bückmann, and M. Wegener, Science 345, 427 (2014)

[3] Experiments on transformation thermodynamics: Molding the flow of heat, R. Schittny, M. Kadic, S. Guenneau, and M. Wegener, Phys. Rev. Lett. 110, 195901 (2013)

[4] An elasto-mechanical unfeelability cloak made of pentamode metamaterials, T. Bückmann,
M. Thiel, M. Kadic, R. Schittny, and M. Wegener, Nature Commun. 5, 4130 (2014)

[5] Cloak design by direct lattice transformation, T. Bückmann, M. Kadic, R. Schittny, and
M. Wegener, Proc. Natl. Acad. Sci. USA 112, 4930 (2015)

[6] Pentamode metamaterials with independently tailored bulk modulus and mass density, M. Kadic, T. Bückmann, R. Schittny, P. Gumbsch, and M. Wegener, Phys. Rev. Appl. 2, 054007 (2014)

[7] Gold helix photonic metamaterial as broadband circular polarizer, J.K. Gansel, M. Thiel, M.S. Rill, M. Decker, K. Bade, V. Saile, G. von Freymann, S. Linden, and M. Wegener, Science 325, 1513 (2009)

[8] Gold triple-helix mid-infrared metamaterial by STED-inspired laser lithography, J. Kaschke and
M. Wegener, Opt. Lett. 40, 3986 (2015)

[9] Three-dimensional optical laser lithography beyond the diffraction limit, J. Fischer and
M. Wegener, Laser Phot. Rev. 7, 22 (2013)