J. Petschulat
University of Jena
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Featured researches published by J. Petschulat.
Optics Express | 2007
Carsten Rockstuhl; Ekaterina Pshenay-Severin; J. Petschulat; A. Chipouline; J. Kuhl; Thomas Pertsch; Harald Giessen; Falk Lederer
We explain the origin of the electric and particular the magnetic polarizabiltiy of metamaterials employing a fully electromagnetic plasmonic picture. As example we study an U-shaped split-ring resonator based metamaterial at optical frequencies. The relevance of the split-ring resonator orientation relative to the illuminating field for obtaining a strong magnetic response is outlined. We reveal higher-order magnetic resonances and explain their origin on the basis of higher-order plasmonic eigenmodes caused by an appropriate current flow in the split-ring resonator. Finally, the conditions required for obtaining a negative index at optical frequencies in a metamaterial consisting of split-ring resonators and wires are investigated.
Optics Express | 2010
J. Petschulat; Dana Cialla; Norik Janunts; Carsten Rockstuhl; Uwe Hübner; Robert Möller; Henrik Schneidewind; Roland Mattheis; Jürgen Popp; Andreas Tünnermann; Falk Lederer; Thomas Pertsch
We report that rhomb-shaped metal nanoantenna arrays support multiple plasmonic resonances, making them favorable bio-sensing substrates. Besides the two localized plasmonic dipole modes associated with the two principle axes of the rhombi, the sample supports an additional grating-induced surface plasmon polariton resonance. The plasmonic properties of all modes are carefully studied by far-field measurements together with numerical and analytical calculations. The sample is then applied to surface-enhanced Raman scattering measurements. It is shown to be highly efficient since two plasmonic resonances of the structure were simultaneously tuned to coincide with the excitation and the emission wavelength in the SERS experiment. The analysis is completed by measuring the impact of the polarization angle on the SERS signal.
ChemPhysChem | 2010
Dana Cialla; J. Petschulat; Uwe Hübner; Henrik Schneidewind; Matthias Zeisberger; Roland Mattheis; Thomas Pertsch; Michael Schmitt; Robert Möller; Jürgen Popp
In general, the electromagnetic mechanism is understood as the strongest contribution to the overall surface-enhanced Raman spectroscopy (SERS) enhancement. Due to the excitation of surface plasmons, a strong electromagnetic field is induced at the interfaces of a metallic nanoparticle leading to a drastic enhancement of the Raman scattering cross-section. Furthermore, the Raman scattered light expierences an emission enhancement due to the plasmon resonances of the nanoantennas. Herein, this second part of the electromagnetic enhancement phenomenon is investigated for different Raman bands of crystal violet by utilizing the anisotropic plasmonic character of gold nanorhomb SERS arrays. We aim at evaluating the effects of localized and propagating surface plasmon polariton modes as well as their combination on the scattered SERS intensity. From that point of view, design and fabrication strategies towards the fabrication of SERS arrays for excitation wavelengths in the visible and near-infrared (NIR) spectral region can be given, also using a double-resonant electromagnetic enhancement.
Analytical and Bioanalytical Chemistry | 2009
Dana Cialla; Ronald Siebert; Uwe Hübner; Robert Möller; Henrik Schneidewind; Roland Mattheis; J. Petschulat; Andreas Tünnermann; Thomas Pertsch; Benjamin Dietzek; Jiirgen Popp
AbstractSurface-enhanced Raman scattering (SERS) is a potent tool in bioanalytical science because the technique combines high sensitivity with molecular specificity. However, the widespread and routine use of SERS in quantitative biomedical diagnostics is limited by tight requirements on the reproducibility of the noble metal substrates used. To solve this problem, we recently introduced a novel approach to reproducible SERS substrates. In this contribution, we apply ultrafast time-resolved spectroscopy to investigate the photo-induced collective charge-carrier dynamics in such substrates, which represents the fundamental origin of the SERS mechanism. The ultrafast experiments are accompanied by scanning-near field optical microscopy and SERS experiments to correlate the appearance of plasmon dynamics with the resultant evanescent field distribution and the analytically relevant SERS enhancement. FigureUltrafast time-resolved differential absorption spectroscopy combined with scanning near-field optical microscopy (left) and atomic force microscopy (right) yields insight into the photoinduced charge-carrier dynamics in innovative reproducible SERS-substrates
Physical Review B | 2010
J. Petschulat; A. Chipouline; Andreas Tünnermann; Thomas Pertsch; Christoph Menzel; Carsten Rockstuhl; Thomas Paul; Falk Lederer
We present a simple model which permits to access the optical properties of planar metamaterials made of unit cells (meta-atoms) which are formed by a set of elementary building blocks, namely, thin metallic wires. In the model, the wires are represented as oscillating electric dipoles which are mutually coupled. The parameters describing the building blocks have to be matched once to let the model reproduce the results of a rigorous simulation or measurement. But afterwards the building blocks can be arranged in quite a different way and the achievable optical properties can be fully explored within the model without further rigorous simulations. The optical properties are accessed at normal incidence only and, for convenience, they can be described in terms of effective material tensors which are assigned to a conceptually homogenous medium causing the same optical response. As an example the model is applied to reveal the occurrence of elliptical dichroism if the split ring resonator meta-atom is modified to L- or S-shaped meta-atoms. The model constitutes an excellent tool to explore new designs of metamaterials.
Optics Express | 2010
J. Petschulat; Yang J; Christoph Menzel; Carsten Rockstuhl; A. Chipouline; Philippe Lalanne; Andreas Tuennermann; Falk Lederer; Thomas Pertsch
We introduce a technique to decompose the scattered near field of two-dimensional arbitrary metaatoms into its multipole contributions. To this end we expand the scattered field upon plane wave illumination into cylindrical harmonics as known from Mies theory. By relating these cylindrical harmonics to the field radiated by Cartesian multipoles, the contribution of the lowest order electric and magnetic multipoles can be identified. Revealing these multipoles is essential for the design of metamaterials because they largely determine the character of light propagation. In particular, having this information at hand it is straightforward to distinguish between effects that result either from the arrangement of the metaatoms or from their particular design.
Optics Letters | 2010
J. Petschulat; Christian Helgert; Michael Steinert; Norbert Bergner; Carsten Rockstuhl; Falk Lederer; Thomas Pertsch; Andreas Tünnermann; Ernst-Bernhard Kley
We study the physics of a new type of subwavelength nanocavities. They are based on U-shaped metal-insulator-metal waveguides supporting the excitation of surface plasmon polaritons. The nanocavity arrays are excited by plane waves at either a normal or oblique incidence. Because of their finite length, discrete modes emerge within the nanocavity. We show that the excitation symmetry with respect to the cavity ends permits the observation of even and odd modes. Our investigations include near- and far-field simulations and predict a strong spectral far-field response of the comparably small nanoresonators. The strong near-field enhancement observed in the cavity at resonance might be suitable to increase the efficiency of nonlinear optical effects and quantum analogies and might facilitate the development of optical elements, such as active plasmonic devices.
Optics Express | 2011
Ekaterina Pshenay-Severin; A. Chipouline; J. Petschulat; Uwe Hübner; Thünnerman A; Thomas Pertsch
We performed theoretical and experimental investigations of the magnetic properties of metamaterials based on asymmetric double-wire structures. Using the multipole model for the description of metamaterials, we investigated the influence of the geometrical asymmetry of the structure on the macroscopic effective parameters. The results show that the larger wire in the system dominates the dynamics of the structure and defines the orientation and the strength of the microscopic currents. As a result the magnetization of the structure can be significantly enhanced for certain asymmetric configurations of the double-wire structure.
Metamaterials | 2008
Carsten Rockstuhl; Christoph Menzel; Thomas Paul; Christian Helgert; Ekaterina Pshenay-Severin; J. Petschulat; A. Chipouline; Thomas Pertsch; Falk Lederer
The properties of metamaterials made of an increasing number of discrete functional layers are analyzed. Convergence of the effective properties towards their bulk counterparts is observed if the light propagation in the metamaterial is dominated by a single eigenmode. The effective properties of the finite structure will be compared to the properties of the infinite structure for which an effective refractive index can be derived from the dispersion relation. The dispersion relation is furthermore shown to be useful in deriving angle dependent effective material parameters. They are compared to the effective properties obtained from a finite slab by applying a dedicated retrieval procedure.
Advances in Optoelectronics | 2012
A. Chipouline; S. Sugavanam; J. Petschulat; Thomas Pertsch
Influence of the short-range lateral disorder in the meta-atoms positioning on the effective parameters of the metamaterials is investigated theoretically using the multipole approach. Random variation of the near field quasi-static interaction between metaatoms in form of double wires is shown to be the reason for the effective permittivity and permeability changes. The obtained analytical results are compared with the known experimental ones.