Carsten Rockstuhl

Karlsruhe Institute of Technology, Carlsruhe, Baden-Württemberg, Germany

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Publications (353)844.71 Total impact

  • Optics Letters 12/2015; 40(23):5626. DOI:10.1364/OL.40.005626 · 3.29 Impact Factor
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    ABSTRACT: 3D photonic crystals (3DPCs) provide light management for solar cells. Here, we fabricate 3DPCs via spray coating, which is a fast, cheap, and scalable technique and apply them as backside structures for solar cells.
    Optical Society of America / Light, Energy and the Environement, Souzhou, China; 11/2015
  • Jako Straubel · Robert Filter · Carsten Rockstuhl · Karolina Słowik ·
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    ABSTRACT: Highly integrated single photon sources are key components in future quantum-optical circuits. Whereas the probabilistic generation of single photons can routinely be done by now, their triggered generation is a much greater challenge. Here, we describe the triggered generation of single photons in a hybrid plasmonic device. It consists of a lambda-type quantum emitter coupled to a multimode optical nanoantenna. For moderate interaction strengths between the subsystems, the description of the quantum optical evolution can be simplified by an adiabatic elimination of the electromagnetic fields of the nanoantenna modes. This leads to an insightful analysis of the emitter's dynamics, entails the opportunity to understand the physics of the device, and to identify parameter regimes for a desired operation. Even though the approach presented in this work is general, we consider a simple exemplary design of a plasmonic nanoantenna, made of two silver nanorods, suitable for triggered generation of single photons.
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    Optica 09/2015; 2(10):850-853. DOI:10.1364/OPTICA.2.000850
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    Ivan Fernandez-Corbaton · Martin Fruhnert · Carsten Rockstuhl ·
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    ABSTRACT: We demonstrate a route to design structures exhibiting optical activity in general scattering directions. This means that when the structure is illuminated from an arbitrary direction, the polarization of the field measured in another arbitrary direction is a rotated version of the incident polarization. The rotation angle does not depend on the incident polarization.
    Piers 2015 Prague, and Metamaterials 2015 Oxford; 09/2015
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    ABSTRACT: The study of high-index dielectric nanoparticles and nanoantennas currently attracts a lot of attention. They do not suffer from absorption but promise to provide control on the properties of light comparable to plasmonic nanoantennas. To further advance the field, it is important to identify versatile dielectric nanoantennas with unconventional properties. Here, we show that breaking the symmetry of an all-dielectric nanoantenna leads to a geometrically tunable magneto-electric coupling, i.e. a strong bianisotropy. The suggested nanoantenna exhibits different backscatterings and, as an interesting consequence, different optical scattering forces for opposite illumination directions. An array of such nanoantennas provides different reflection phases when illuminated from opposite directions. With a proper geometrical tuning, this bianisotropic nanoantenna is capable of providing a $2\pi$ phase change in the reflection spectrum while possessing a rather large and constant amplitude. This allows creating reflectarrays with near-perfect transmission out of the resonance band due to the absence of an usually employed metallic screen.
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    Ivan Fernandez-Corbaton · Carsten Rockstuhl ·
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    ABSTRACT: We introduce a definition of the electromagnetic chirality of an object and show that it has an upper bound. The upper bound is attained if and only if the object is transparent for fields of one handedness (helicity). Additionally, electromagnetic duality symmetry, i.e. helicity preservation upon scattering, turns out to be a necessary condition for reciprocal scatterers to attain the upper bound. We use these results to provide requirements for the design of such extremal scatterers. The requirements can be formulated as constraints on the polarizability tensors for dipolar scatterers or as material constitutive relations. We also outline two applications for objects of maximum electromagnetic chirality: A twofold resonantly enhanced and background free circular dichroism measurement setup, and angle independent helicity filtering glasses.
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    ABSTRACT: We report on the investigation of an advanced circular plasmonic nanoantenna under ultrafast excitation using nonlinear photoemission electron microscopy (PEEM) under near-normal incidence. The circular nanoantenna is enhanced in its performance by a supporting grating and milled out from a gold film. The considered antenna shows a sophisticated physical resonance behavior that is ideal to demonstrate the possibilities of PEEM for the experimental investigations of plasmonic effects on the nanoscale. Field profiles of the antenna resonance for both possible linear polarizations of the incident field are measured with high spatial resolution. In addition, outward propagating Hankel plasmons, which are also excited by the structure, are measured and analyzed. We compare our findings to measurements of an isolated plasmonic nanodisc resonator and scanning near-field optical microscopy (SNOM) measurements of both structures. All results are in very good agreement with numerical simulations as well as analytial models that are also discussed in our paper.
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    ABSTRACT: Plasmonic nanoantennas can feature a sophisticated spectral response that may be the springboard for a plethora of applications. Particularly, spectrally sharp Fano resonances have been at the focus of interest because of their promising applications in sensing. Usually, the observation of Fano resonances requires nanostructures that exhibit multiple plasmonic resonances such as higher-order multipole moments. We show that similar spectral features can be observed with nanoantennas sustaining solely electric-dipolar resonances. The considered nanoantennas consist of multiple concentric gold nanorings separated by thin dielectric spacers. These nanoantennas host multiple resonances with disparate line widths in the visible and near-infrared. We theoretically and experimentally show that the interference of these resonances causes Fano features and scattering dark states. The electric-dipolar character permits the use of a simplified dense-array theory to predict the response of arrays of such nanoantennas from the electric polarizability of the individual constituents. This paves the way for a simplified design of plasmonic metasurfaces.
    07/2015; 2(8):150713144200008. DOI:10.1021/acsphotonics.5b00133
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    ABSTRACT: Bonding individual metallic nanoparticles at small separation distances to let them form dimers and making them available in large quantities is a key requirement for various applications that wish to exploit the tremendous enhancement of electromagnetic fields in plasmonic junctions. Although progress has been witnessed in the past concerning the fabrication of dimers mediated by rigid molecular linkers, the exact bonding mechanism remains unclear. Here, we describe the fabrication of a rigid linker molecule and demonstrate its feasibility to achieve dimers made from closely spaced metallic nanoparticles in large quantities. Although the topography of the dimers proofs the success of the fabrication method, we use what we call a hypermethod characterization approach to study the optical properties of dimers from various perspectives. Measuring the surface enhanced Raman scattering signal of the linker molecule enables tracing directly the optical environment it perceives. By reaching a strong field enhancement in the gap of the dimers, we are able to investigate optical and geometrical properties of the linker. Moreover, upon isolation of the dimers, we use single particle extinction spectroscopy to study the optical response of a fabricated dimer directly. Full wave numerical simulations corroborate the experimental results and provide insights into quantities, which cannot be accessed directly in experiments. The ability to fabricate and to characterize rigidly linked nanoparticles will pave the way towards various plasmonic applications such as sensors, photocatalysis, and plexcitonics.
    The Journal of Physical Chemistry C 07/2015; 119(31). DOI:10.1021/acs.jpcc.5b04346 · 4.77 Impact Factor
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    Ivan Fernandez-Corbaton · Stefan Nanz · Rasoul Alaee · Carsten Rockstuhl ·
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    ABSTRACT: The multipolar decomposition of current distributions is used in many branches of physics. Here, we obtain new exact expressions for the dipolar moments of a localized electric current distribution. The typical integrals for the dipole moments of electromagnetically small sources are recovered as the lowest order terms of the new expressions in a series expansion with respect to the size of the source. All the higher order terms can be easily obtained. We also provide exact and approximated expressions for dipoles that radiate a definite polarization handedness (helicity). Formally, the new exact expressions are only marginally more complex than their lowest order approximations.
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    Ivan Fernandez-Corbaton · Stefan Nanz · Carsten Rockstuhl ·
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    ABSTRACT: Toroidal multipoles are attracting research attention, particularly in the field of metamaterials. They are often understood as a multipolar family in its own right. The dynamic toroidal multipoles emerge from the separation of one of the two transverse multipoles into two parts, referred to as electric and toroidal. Here, we establish that the dynamic toroidal multipolar components of an electric current distribution cannot be determined by measuring the radiation from the source or its coupling to external electromagnetic waves. We analytically show how the split into electric and toroidal parts causes the appearance of non-radiative components in each of the two parts, which cancel when summed back together. The toroidal multipoles do not have an independent meaning with respect to their interaction with the radiation field. Their formal meaning is clear, however. They are the higher order terms of an expansion of the multipolar coefficients of electric parity with respect to the electromagnetic size of the source.
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    ABSTRACT: In this paper, we propose, design, theoretically study, and experimentally test a simple periodical array which provides perfect absorptivity when one of its surfaces is illuminated and controllable reflectivity for illuminations of the other side. The proposed structure does not contain any ground plane and relies on the bianisotropic properties of the unit cells forming the absorbing layer. The absence of the ground plane makes the new design suitable for applications where the absorber should not block transmission outside the absorption band. The proposed structure is realized as an array of nonidentical conducting patches imprinted on the two sides of a thin dielectric slab. This ultra-thin ($simlambda/150$, where $lambda$ is the operational wavelength) metasurface absorber is optimized, fabricated, and tested. The test results confirm nearly perfect absorption (from one direction) and controllable reflection (from the other direction) at the resonance frequency, as well as partial transparency outside of the absorption band.
    IEEE Transactions on Antennas and Propagation 07/2015; 63(7):1-1. DOI:10.1109/TAP.2015.2423855 · 2.18 Impact Factor
  • R Alaee · R Filter · D Lehr · F Lederer · C Rockstuhl ·
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    ABSTRACT: A nanoantenna with balanced electric and magnetic dipole moments, known as the first Kerker condition, exhibits a directive radiation pattern with zero backscattering. In principle, a nanoantenna can provide even better directionality if higher order moments are properly balanced. Here, we study a generalized Kerker condition in the example of a nanoring nanoantenna supporting electric dipole and electric quadrupole moments. Nanoring antennas are well suited since both multipole moments can be almost independently tuned to meet the generalized Kerker condition.
    Optics Letters 06/2015; 40(11):2645-2648. DOI:10.1364/OL.40.002645 · 3.29 Impact Factor
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    ABSTRACT: Optical plasmonic antennas allow for localizing and enhancing light at the nanoscale. To enhance the application opportunities of optical antennas, their quality factor needs to be substantially improved. Here, we numerically and experimentally demonstrate that the resonance of a dipolar metallic disc antenna can be enhanced by a circular grating that obeys the Bragg condition. The supporting grating effectively collects energy from an extended spatial domain and guides it spectrally-selected into the central antenna, leading to a significantly enhanced field intensity at resonance. Accordingly, the quality factor of the antenna is enhanced by at least five times. The approach can be applied to other plasmonic systems, hence constituting an important ingredient to a future plasmonic tool box.
    Optics Express 06/2015; 23(11):14583. DOI:10.1364/OE.23.014583 · 3.49 Impact Factor
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    ABSTRACT: We design by transformation optics, fabricate by three-dimensional direct laser writing, and characterize experimentally polymer-based cloaks for 20 µm wide gold-wire contacts on a silicon wafer. The contact shadowing effect is reduced by 90%.
    CLEO / Optical Society of America, San Jose, California United States; 05/2015
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    M. Albooyeh · R. Alaee · C. Rockstuhl · C. Simovski ·
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    ABSTRACT: Recently, it has been shown that a metasurface of plasmonic nanospheres deposited on a highly refractive substrate requires a bianisotropic magnetoelectric coupling for its effective description. The effect has been coined substrate-induced bianisotropy. It leads to an asymmetric reflectance similar to bianisotropic metasurfaces. In this work, through a circuit model, we show that such bianisotropy does not necessarily emerge for all substrated metasurfaces. Indeed, we show that the thickness of the metasurface plays a crucial role to encounter substrate-induced bianisotropy. Moreover, by taking advantage of substrate-induced bianisotropy, we present the necessary conditions for the circuit model parameters to compensate the asymmetric reflectance generated by an intrinsically bianisotropic metasurface. We finally express that, in substrated metasurfaces, the asymmetric reflectance and the bianisotropic response are two separate issues albeit with interdependencies.
    Physical Review B 05/2015; 91(19). DOI:10.1103/PhysRevB.91.195304 · 3.74 Impact Factor
  • T. Kaiser · M. Falkner · J. Qi · M. Steinert · C. Menzel · C. Rockstuhl · T. Pertsch ·
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    ABSTRACT: We theoretically and experimentally investigate circular plasmonic disc nanoantennas enhanced in their performance by a surrounding Bragg grating ring structure. PEEM investigations are demonstrated to provide unprecedented insights into the field localization and enhancement.
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Publication Stats

6k Citations
844.71 Total Impact Points


  • 2014-2015
    • Karlsruhe Institute of Technology
      • Institute for Theoretical Solid State Physics
      Carlsruhe, Baden-Württemberg, Germany
  • 2008-2014
    • Universitätsklinikum Jena
      Jena, Thuringia, Germany
    • Waseda University
      • Department of Electrical Engineering and Bioscience
      Edo, Tōkyō, Japan
  • 2005-2014
    • Friedrich Schiller University Jena
      • • Institute of Organic Chemistry and Macromolecular Chemistry
      • • Department of Condensed Matter and Optics
      • • Department of Applied Physics
      Jena, Thuringia, Germany
  • 2012-2013
    • The University of Sheffield
      • Department of Materials Science and Engineering
      Sheffield, England, United Kingdom
    • Oklahoma State University - Stillwater
      • School of Electrical and Computer Engineering
      Stillwater, OK, United States
  • 2005-2007
    • National Institute of Advanced Industrial Science and Technology
      • Electronics and Photonics Research Institute
      Tsukuba, Ibaraki, Japan
  • 2001-2006
    • Université de Neuchâtel
      • Laboratoire Temps-Fréquence (LTF)
      Neuenburg, Neuchâtel, Switzerland