Ulf Peschel

Publications (48)184.42 Total impact

• Article: Nanointerferometric Amplitude and Phase Reconstruction of Tightly Focused Vector Beams

  Thomas Bauer, Sergej Orlov, Ulf Peschel, Peter Banzer, Gerd Leuchs
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  ABSTRACT: Highly confined vectorial electromagnetic field distributions represent an excellent tool for detailed studies in nano-optics and high resolution microscopy, such as nonlinear microscopy, advanced fluorescence imaging or nanoplasmonics. Such field distributions can be generated, for instance, by tight focussing of polarized light beams. To guarantee high quality and resolution in the investigation of objects with sub-wavelength dimensions, the precise knowledge of the spatial distribution of the exciting vectorial field is of utmost importance. Full-field reconstruction methods presented so far involved, for instance, complex near-field techniques. Here, we demonstrate a simple and straight-forward to implement measurement scheme and reconstruction algorithm based on the scattering signal of a single spherical nanoparticle as a field-probe. We are able to reconstruct the amplitudes of the individual focal field components as well as their relative phase distributions with sub-wavelength resolution from a single scan measurement without the need for polarization analysis of the scattered light. This scheme can help to improve modern microscopy and nanoscopy techniques.
  04/2013;
• Article: Observation of Defect States in PT-Symmetric Optical Lattices

  Alois Regensburger, Mohammad-Ali Miri, Christoph Bersch, Jakob Näger, Georgy Onishchukov, Demetrios N. Christodoulides, Ulf Peschel
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  ABSTRACT: We provide the first experimental demonstration of defect states in parity-time (PT) symmetric mesh-periodic potentials. Our results indicate that these localized modes can undergo an abrupt phase transition in spite of the fact that they remain localized in a PT-symmetric periodic environment. Even more intriguing is the possibility of observing a linearly growing radiation emission from such defects provided their eigenvalue is associated with an exceptional point that resides within the continuum part of the spectrum. Localized complex modes existing outside the band-gap regions are also reported along with their evolution dynamics.
  01/2013;
• Source

  Available from: Sergej Orlov

  Article: Probing guided modes in a monolayer colloidal crystal on a flat metal film

  Sergei G Romanov, Nicolas Vogel, Karina Bley, Katharina Landfester, Clemens K Weiss, Sergej Orlov, Alexander V Korovin, Gennady P Chuiko, Alois Regensburger, Alexandra S Romanova, Arian Kriesch, Ulf Peschel
  Phys. Rev. B. 11/2012; 86(19):195145.
• Source

  Available from: Arian Kriesch

  Dataset: Experimental cross-polarization detection of coupling far-field light to highly confined plasmonic gap modes via nanoantennas

  Jing Wen, Peter Banzer, Arian Kriesch, Daniel Ploss, Bernhard Schmauss, Ulf Peschel
• Article: Optical mesh lattices with PT-symmetry

  Mohammad-Ali Miri, Alois Regensburger, Ulf Peschel, Demetrios N. Christodoulides
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  ABSTRACT: We investigate a new class of optical mesh periodic structures that are discretized in both the transverse and longitudinal directions. These networks are composed of waveguide arrays that are discretely coupled while phase elements are also inserted to discretely control their effective potentials and can be realized both in the temporal and the spatial domain. Their band structure and impulse response is studied in both the passive and parity-time (PT) symmetric regime. The possibility of band merging and the emergence of exceptional points along with the associated optical dynamics are considered in detail both above and below the PT-symmetry breaking point. Finally unidirectional invisibility in PT-synthetic mesh lattices is also examined along with possible superluminal light transport dynamics.
  08/2012;
• Article: Parity-time synthetic photonic lattices.

  Alois Regensburger, Christoph Bersch, Mohammad-Ali Miri, Georgy Onishchukov, Demetrios N Christodoulides, Ulf Peschel
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  ABSTRACT: The development of new artificial structures and materials is today one of the major research challenges in optics. In most studies so far, the design of such structures has been based on the judicious manipulation of their refractive index properties. Recently, the prospect of simultaneously using gain and loss was suggested as a new way of achieving optical behaviour that is at present unattainable with standard arrangements. What facilitated these quests is the recently developed notion of 'parity-time symmetry' in optical systems, which allows a controlled interplay between gain and loss. Here we report the experimental observation of light transport in large-scale temporal lattices that are parity-time symmetric. In addition, we demonstrate that periodic structures respecting this symmetry can act as unidirectional invisible media when operated near their exceptional points. Our experimental results represent a step in the application of concepts from parity-time symmetry to a new generation of multifunctional optical devices and networks.
  Nature 08/2012; 488(7410):167-71. · 36.28 Impact Factor
• Article: Optical gap solitons and truncated nonlinear Bloch waves in temporal lattices

  Christoph Bersch, Georgy Onishchukov, Ulf Peschel
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  ABSTRACT: We experimentally demonstrate the formation and stable propagation of various types of discrete temporal solitons in an optical fiber system. Pulses interacting with a time-periodic potential and defocusing nonlinearity are shown to form gap solitons and nonlinear truncated Bloch waves. Multi-pulse solitons with defects, as well as novel structures composed of a strong soliton riding on a weaker truncated nonlinear Bloch wave are shown to propagate over up to eleven coupling lengths. The nonlinear dynamics of all pulse structures is monitored over the full propagation distance which provides detailed insight into the soliton dynamics.
  07/2012;
• Article: Tuning the structural properties of femtosecond-laser-induced nanogratings

  Lourdes Patricia R. Ramirez, Matthias Heinrich, Sören Richter, Felix Dreisow, Robert Keil, Alexander V. Korovin, Ulf Peschel, Stefan Nolte, Andreas Tünnermann
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  ABSTRACT: We present the results of our investigations on the formation process of nanogratings in fused silica and the influence of fabrication parameters, thereby identifying ways to systematically control the grating properties. Nanogratings, self-organized nanostructures with subwavelength periodicity, are formed in certain parameter ranges during femtosecond-laser processing of transparent materials, resulting in characteristic birefringent modifications. They provide the opportunity for the fabrication of arbitrary three-dimensional birefringent elements with position-dependent retardation. Based on our findings, we were able to fabricate birefringent elements with various precise retardations in otherwise isotropic fused silica.
  Applied Physics A 04/2012; 100(1):1-6. · 1.63 Impact Factor
• Article: The role of self-trapped excitons and defects in the formation of nanogratings in fused silica.

  Sören Richter, Fei Jia, Matthias Heinrich, Sven Döring, Ulf Peschel, Andreas Tünnermann, Stefan Nolte
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  ABSTRACT: We investigate the role of self-trapped excitons (STEs) and defects in the formation of femtosecond laser pulse induced nanogratings (NGs) in fused silica. Our experiments reveal strongly enhanced NG formation for pulse separations up to the STE lifetime. In addition, the absorption spectra show that the weaker cumulative action of laser pulses for longer temporal separations is predominantly mediated by dangling-bond-type lattice defects that emerge from decaying STEs.
  Optics Letters 02/2012; 37(4):482-4. · 3.40 Impact Factor
• Conference Proceeding: Hybrid architectures: enabling 4-dimensional plasmonic-photonic crystals

  Sergei G Romanov, Alexander V Korovin, M Reza Bahrami, Ulf Peschel
  Proc. SPIE; 01/2012
• Conference Proceeding: Interplay of Mie and Bragg resonances in partly ordered monolayers of colloidal spheres

  Sergei G Romanov, Sergei Orlov, Alexander V Korovin, Oleksandr Zhuromskyy, Nicolas Vogel, Katharina Landfester, Clemens K Weiss, Ulf Peschel
  Proc. SPIE; 01/2012
• Source

  Available from: ArXiv

  Article: Photon propagation in a discrete fiber network: an interplay of coherence and losses.

  Alois Regensburger, Christoph Bersch, Benjamin Hinrichs, Georgy Onishchukov, Andreas Schreiber, Christine Silberhorn, Ulf Peschel
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  ABSTRACT: We study light propagation in a photonic system that shows stepwise evolution in a discretized environment. It resembles a discrete-time version of photonic waveguide arrays or quantum walks. By introducing controlled photon losses to our experimental setup, we observe unexpected effects like subexponential energy decay and formation of complex fractal patterns. This demonstrates that the interplay of linear losses, discreteness and energy gradients leads to genuinely new coherent phenomena in classical and quantum optical experiments. Moreover, the influence of decoherence is investigated.
  Physical Review Letters 12/2011; 107(23):233902. · 7.37 Impact Factor
• Article: Negative Goos-Hänchen shift in periodic media.

  Mikael C Rechtsman, Yaroslav V Kartashov, Frank Setzpfandt, Henrike Trompeter, Lluis Torner, Thomas Pertsch, Ulf Peschel, Alexander Szameit
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  ABSTRACT: We show that, under certain conditions, a negative Goos-Hänchen shift-a longitudinal displacement of a totally internally reflected wave packet-occurs in periodic media such as waveguide arrays.
  Optics Letters 11/2011; 36(22):4446-8. · 3.40 Impact Factor
• Article: Hybrid colloidal plasmonic-photonic crystals.

  Sergei G Romanov, Alexander V Korovin, Alois Regensburger, Ulf Peschel
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  ABSTRACT: We review the recently emerged class of hybrid metal-dielectric colloidal photonic crystals. The hybrid approach is understood as the combination of a dielectric photonic crystal with a continuous metal film. It allows to achieve a strong modification of the optical properties of photonic crystals by involving the light scattering at electronic excitations in the metal component into moulding of the light flow in series to the diffraction resonances occurring in the body of the photonic crystal. We consider different realizations of hybrid plasmonic-photonic crystals based on two- and three-dimensional colloidal photonic crystals in association with flat and corrugated metal films. In agreement with model calculations, different resonance phenomena determine the optical response of hybrid crystals leading to a broadly tuneable functionality of these crystals.
  Advanced Materials 06/2011; 23(22-23):2515-33. · 13.88 Impact Factor
• Article: PLASMONIC-PHOTONIC CRYSTALS: Hybrid Colloidal Plasmonic-Photonic Crystals (Adv. Mater. 22-23/2011).

  Sergei G Romanov, Alexander V Korovin, Alois Regensburger, Ulf Peschel
  Advanced Materials 06/2011; 23(22-23):2514. · 13.88 Impact Factor
• Article: Painting by numbers: nanoparticle-based colorants in the post-empirical age.

  Robin N Klupp Taylor, Frantisek Seifrt, Oleksandr Zhuromskyy, Ulf Peschel, Günter Leugering, Wolfgang Peukert
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  ABSTRACT: The visual appearance of the artificial world is largely governed by films or composites containing particles with at least one dimension smaller than a micron. Over the past century and a half, the optical properties of such materials have been scrutinized and a broad range of colorant products, based mostly on empirical microstructural improvements, developed. With the advent of advanced synthetic approaches capable of tailoring particle shape, size and composition on the nanoscale, the question of what is the optimum particle for a certain optical property can no longer be answered solely by experimentation. Instead, new and improved computational approaches are required to invert the structure-function relationship. This progress report reviews the development in our understanding of this relationship and indicates recent examples of how theoretical design is taking an ever increasingly important role in the search for enhanced or multifunctional colorants.
  Advanced Materials 06/2011; 23(22-23):2554-70. · 13.88 Impact Factor
• Source

  Available from: ArXiv

  Article: Zitterbewegung, Bloch Oscillations and Landau-Zener Tunneling in a Quantum Walk

  Alois Regensburger, Christoph Bersch, Benjamin Hinrichs, Georgy Onishchukov, Andreas Schreiber, Christine Silberhorn, Ulf Peschel
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  ABSTRACT: We experimentally investigate a discrete time quantum walk in a system of coupled fiber loops and observe typical phenomena known from the wave propagation in periodic structures as ballistic spreading or an oscillation between two internal quantum states similar to Zitterbewegung (trembling motion). If a position-dependent phase gradient is applied we find localization and Bloch oscillations of the field for moderate as well as Landau-Zener tunneling for strong phase gradients.
  04/2011;
• Article: Frustrated quantum phase diffusion and increased coherence of solitons due to nonlocality

  Sascha Batz, Ulf Peschel
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  ABSTRACT: We investigate the quantum properties of solitons with nonlocal self-interaction. We find significant changes when compared to the local interaction. Quantum phase diffusion of nonlocal solitons is always reduced with respect to the local interaction and vanishes in the strongly nonlocal limit. Thus, coherence is increased in the nonlocal case. Furthermore, we compare the intrinsic quantum wave packet spreading to the recently discussed classical Gordon-Haus effect for nonlocal solitons [ V. Folli and C. Conti Phys. Rev. Lett. 104 193901 (2010)].
  Phys. Rev. A. 03/2011; 83(3).
• Source

  Available from: Arian Kriesch

  Article: Experimental cross-polarization detection of coupling far-field light tohighly confined plasmonic gap modes via nanoantennas

  Jing Wen, Peter Banzer, Arian Kriesch, Daniel Ploss, Bernhard Schmauss, Ulf Peschel
  [show abstract] [hide abstract]
  ABSTRACT: We experimentally demonstrate the coupling of far-field light to highly confined plasmonic gap modes via connected nanoantennas. The excitation of plasmonic gap modes is shown to depend on the polarization, position and wavelength of the incident beam. Far-field measurements performed in crossed polarization allow for the detection of extremely weak signals re-emitted from gap waveguides and can increase the signal-to-noise ratio dramatically.
  Applied Physics Letters 02/2011; 98. · 3.84 Impact Factor
• Article: Perfect imaging of hypersurfaces via transformation optics.

  Klaus Mantel, Dustin Bachstein, Ulf Peschel
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  ABSTRACT: Conventional optical imaging systems suffer from the presence of many imperfections, such as spherical aberrations, astigmatism, or coma. If the imaging system is corrected for spherical aberrations and fulfills the Abbe sine condition, perfect imaging is guaranteed between two parallel planes but only in a small neighborhood of the optical axis. It is therefore worth asking for optical systems that would allow for perfect imaging between arbitrary smooth surfaces without restrictions in shape or extension. In this Letter, we describe the application of transformation optics to design refractive index distributions that allow perfect, aberration-free imaging for various imaging configurations in R(n). A special case is the imaging between two extended parallel lines in R(2), which leads to the well-known hyperbolic secant index distribution that is used for the fabrication of gradient index lenses.
  Optics Letters 01/2011; 36(2):199-201. · 3.40 Impact Factor