Research Bio.

Since 03/2010
     Research Fellow in the group of Prof. U. Leonhardt
     Experimental Examination of Optical Event Horizons

2008-2010
     Postdoc in the group of Prof. R. Ramesh,
     Physics Department, University of California, Berkeley,
     Materials Sciences, Lawrence Berkeley National Laboratory
     Superlenses based on Ferroics
     Funded by the “German Academic Science Foundation –
     Deutscher Akademische Austauschdienst (DAAD)”

2007-2008
     Research group leader as part of DFG project DFG-EN 434/22-1,
     Prof. L.M. Eng, Institute of Applied Photophysics, TU Dresden and
     Prof. Helm, Forschungszentrum Dresden-Rossendorf, Germany
     Near-field microscopy in combination with a free-electron laser

Aug. 2007
     PhD in physics (summa cum laude, with distinction)

2002-2007
     Research assistant as part of doctoral program
     ”Scattering scanning near-field optical microscopy on anisotropic dielectrics”
     in the group of Prof. L.M. Eng,
     Institute of Applied Photophysics, TU Dresden, Germany
     Funded from 2004-2006 by the “Studienstiftung des Deutschen Volkes”

2003
     Exchange program: “Near-field optics on ferroelectrics”  
     Gary Wiederrecht and Stephen Streiffer,
     Argonne National Laboratory, IL, USA

2001-2002
     Diploma program “s-SNOM on ferroelectrics”,
     Group of Prof. Dr. L.M. Eng,
     Institute of Applied Physics/Photophysics, TU Dresden, Germany
     awarded by Harry Dember Award of the Zentrum für Angewandte Photonik

1997-2002
     Academic studies (major: physics), TU Dresden, Germany

CURRENT COLLABORATIONS

USA
     Prof. Ramamoorthy Ramesh, UC Berkeley
     Dr. Yongmin Liu, Prof. Xiang Zhang, UC Berkeley
     Dr. Carl Poitras, Prof. Michal Lipson, Cornell University
Germany
     Prof. Manfred Helm, Forschungszentrum Dresden-Rossendorf
     Prof. Lukas M. Eng, Technische Universität Dresden

Current Research

I study the optical analogy of black hole event horizons in the laboratory. Such event horizons are expected in moving media or moving refractive-index changes. When a pulse is sent into a fiber or waveguide, it’s electric fields change the local refractive index due to the Kerr effect. As the pulse travels almost with the speed of light in the fiber, the local refractive-index change moves with it, creating an event horizon. For the special case of a black hole event horizon, we expect to observe Hawking radiation. This radiation is created from vacuum fluctuations at the horizon and consists of photon-photon pairs, which can be observed as correlated pairs at defined wavelengths.

Research Topics

Dr. Kehr's research topics include:

• Transformation optics
• Fibre-optical black holes
• Perfect Imaging
• Few-cycle Pulses in Fibres
• 'Cherenkov' Radiation

Publications

2011

S.C. Kehr.
Near-field Microscopy with Superlenses.
Wiley/G.I.T. Imaging & Microscopy 4, 22-25 (2011).
http://www.imaging-git.com/science/scanning-probe-microscopy/near-field-microscopy-superlenses

A. Di Falco, S.C. Kehr, and U. Leonhardt.
Luneburg lens in Silicon-on-Insulator platform.
Integrated Photonic Research, Silicon and Nanophotonics (IPRSN), OSA Technical Digest (CD) (Optical Society of America 2011), paper IMD4.

http://www.opticsinfobase.org/abstract.cfm?URI=IPRSN-2011-IMD4

S.C. Kehr, Y.G. Ma, S. Sahebdivan, A. Di Falco, T. Philbin, A.J. Danner, T. Tyc, and U. Leonhard.
Sub-diffraction-limited imaging in the far-field.
Fifth International Congress on Advanced Electro-magnetic Materials in Microwaves and Optics, 991-993 (2011). 

http://proceedings.metamorphose-vi.org

S.C. Kehr, P. Yu, Y. Liu, M. Parzefall, A.I. Khan, R. Jacob, M.T. Wenzel, H.-G. Von Ribbeck, M. Helm, X. Zhang, L.M. Eng, and R. Ramesh.
Microspectroscopy on pervoskite-based superlenses.
Optical Materials Express 1, 1051-1060 (2011) (invited).

S.C. Kehr, Y. Liu, L.W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M.T. Wenzel, R. Jacob, H.-G. Von Ribbeck, M. Helm, X. Zhang, L.M. Eng, and R. Ramesh.
Near-field examination of perovskite-based superlenses and superlens- enhanced probe-object coupling.
Nature Communications 2, 249, doi:10.1038/ncomms1249 (2011).

A. Di Falco, S.C. Kehr, and U. Leonhardt.
Luneburg lens in silicon photonics.
Optics Express 19 (6), 5156-5162 (2011).

2010

R. Jacob, S. Winnerl, H. Schneider, M. Helm, M.T. Wenzel, H.-G. von Ribbeck, L.M. Eng, and S.C. Kehr.
Quantitative determination of the charge carrier concentration of sub-surface implanted silicon by IR-near-field spectroscopy.
Optics Express 18 (25), 26206-26213 (2010).

S.C. Kehr, Y.M. Liu, P. Yu, L.W. Martin, M. Helm, X. Zhang, L.M. Eng, and R. Ramesh.
Oxide-based superlenses in the infrared regime.
Fourth International Congress on Advanced Electro-magnetic Materials in Microwaves and Optics, 628- 630 (2010).
http://proceedings.metamorphose-vi.org

2009

S.C. Kehr, L.M. Eng, and R. Ramesh. Tunable Perfect Lens Based on Ferroelectrics.
3rd International Congress on Advanced Electromagnetic Materials in Microwaves and Optics, 629-631 (2009).
http://proceedings.metamorphose-vi.org

M.P. Nikiforov, S.C. Kehr, T.-H. Park, P. Milde, U. Zerweck, C. Loppacher, L.M. Eng, M.J. Therien, N. Engheta, and D. Bonnell.
Probing polarization and dielectric function of molecules with higher order harmonics in scattering-near-field scanning optical microscopy.
Journal of Applied Physics 106, 114307 (2009).

2008

M.T. Wenzel, T. Härtling, P. Olk, S.C. Kehr, S. Grafström, S. Winnerl, M. Helm, and L.M. Eng.
Gold nanoparticle tips for optical field confinement in infrared scattering near-field optical microscopy.
Optics Express 16 (16), 12302-12312 (2008).

S.C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L.M. Eng, S. Winnerl, D. Stehr, and M. Helm.
Anisotropy contrast in phonon-enhanced apertureless near-field microscopy using a free-electron laser.
Physical Review Letters 100, 256403 (2008).

2003-2007

S.C. Schneider, J. Seidel, S. Grafström, L.M. Eng, S. Winnerl, D. Stehr, and M. Helm.
Impact of optical in-plane anisotropy on near-field phonon polariton spectroscopy.
Applied Physics Letters 90, 143101-143103 (2007).

S. Winnerl, D. Stehr, O. Drachenko, H. Schneider, M. Helm, W. Seidel, P. Michel, S. Schneider, J. Seidel, S. Grafström, L.M. Eng , T. Roch, G. Strasser, T. Maier, M. Walther.
FELBE Free-Electron-Laser: Status and Application for Time Resolved Spectroscopy Experiments.
Proceedings paper in Conference Digest, Joint 31st International Conference on Infrared and Millimeter Waves and 14th International Conference on Terahertz Electronics (IRMMW-THz), 159-159 (2006).

S.C. Schneider, S. Grafström, and L.M. Eng.
Scattering scanning near-field optical microscopy of optically anisotropic systems.
Physical Review B 71 (1), 115418-1-8 (2005).

Ch. Loppacher, F. Schlaphof, S. Schneider, U. Zerweck, S. Grafström, L.M. Eng, A. Roelofs, and R. Waser.
Lamellar ferroelectric domains in PbTiO3 grains imaged and manipulated by AFM.
Surface Science 532-535, 483-487 (2003).