Ulf Peschel - Academia.edu (original) (raw)

Papers by Ulf Peschel

2011 Conference on Lasers and Electro Optics Europe and 12th European Quantum Electronics Conference, 2011

A unique feature of superfluidity is the frictionless flow below a critical velocity. This was fi... more A unique feature of superfluidity is the frictionless flow below a critical velocity. This was first pointed out by L. D. Landau who argued that only above the speed of sound the excitations of linear or sound waves is energetically favoured (1) leading to a finite drag and to a break down of superfluidity. The superfluid motion of a dilute

2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE/EQEC), 2011

A unique feature of superfluidity is the frictionless flow below a critical velocity. This was fi... more A unique feature of superfluidity is the frictionless flow below a critical velocity. This was first pointed out by L. D. Landau who argued that only above the speed of sound the excitations of linear or sound waves is energetically favoured (1) leading to a finite drag and to a break down of superfluidity. The superfluid motion of a dilute

Quantum Electronics and Laser Science Conference Technical Digest Postconference Edition Tops Vol 40, May 12, 2000

Summary form only given. Waveguide arrays are regarded as key components in future steering and r... more Summary form only given. Waveguide arrays are regarded as key components in future steering and routing schemes, because they allow us to distribute signals between many different channels. Therefore several present experimental activities have focused on the formation and dynamics of discrete solitons. AlGaAs samples were operated below half the bandgap to employ the focusing Kerr nonlinearity. For single-mode waveguides

Nonlinear Guided Waves and Their Applications, 2004

ABSTRACT We introduce an analytical approach which permits to identify domains of existence in pa... more ABSTRACT We introduce an analytical approach which permits to identify domains of existence in parameter space of discrete cavity solitons. We demonstrate the performance of the approach for solitons in an array of quadratically nonlinear cavities.

Nonlinear Guided Waves and Their Applications, 2005

ABSTRACT We report for the first time on the existence of dissipative lattice solitons in a quadr... more ABSTRACT We report for the first time on the existence of dissipative lattice solitons in a quadratically nonlinear cavity with a periodic modulation of the refractive index. We observe various localized structures, in particular multiband solitons.

Physical Review Letters, 2004

ACS Photonics, 2016

The ability to confine and manipulate light below the diffraction limit is a major goal of future... more The ability to confine and manipulate light below the diffraction limit is a major goal of future multifunctional optoelectronic/plasmonic systems. Here, we demonstrate the design and realization of a tunable and localized electrical source of excitons coupled to surface plasmons based on a polymer light-emitting field-effect transistor (LEFET). Gold nanorods that are integrated into the channel support localized surface plasmons and serve as nanoantennas for enhanced electroluminescence. By precise spatial control of the near-infrared emission zone in the LEFET via the applied voltages the near-field coupling between electrically generated excitons and the nanorods can be turned on or off as visualized by a change of electroluminescence intensity. Numerical calculations and spectroscopic measurements corroborate significant local electroluminescence enhancement due to the high local density of photonic states in the vicinity of the gold nanorods. Importantly, the integration of plasmonic nanostructures hardly influences the electrical performance of the LEFETs, thus, highlighting their mutual compatibility in novel active plasmonic devices.

Nonlinear Optics: Materials, Fundamentals and Applications, 2000

Physical Review Letters, Oct 1, 2010

We experimentally study the impact of intrinsic and extrinsic curvature of space on the evolution... more We experimentally study the impact of intrinsic and extrinsic curvature of space on the evolution of light. We show that the topology of a surface matters for radii of curvature comparable with the wavelength, whereas for macroscopically curved surfaces only intrinsic curvature is relevant. On a surface with constant positive Gaussian curvature we observe periodic refocusing, self-imaging, and diffractionless propagation. In contrast, light spreads exponentially on surfaces with constant negative Gaussian curvature. For the first time we realized two beam interference in negatively curved space.

Optical Design and Engineering II, 2005

For gaining a deeper understanding of the diffraction processes that take place in deep dielectri... more For gaining a deeper understanding of the diffraction processes that take place in deep dielectric transmission gratings, a phenomenological explanation has been developed on the basis of a modal field, which propagates vertically through the grating region. The excitation of these modes by the incident wave, their propagation constants and how they couple to the diffraction orders determines the diffraction efficiency of the transmitted orders. The explicit modal analysis discloses the description of the highly efficient diffraction for polarized or unpolarized light by a very simple interference mechanism, which will be the subject of this paper.

Physical Review B

Lossless propagation of longitudinal magnetic dipole waves along chains of high-index subwaveleng... more Lossless propagation of longitudinal magnetic dipole waves along chains of high-index subwavelength particles is predicted for a narrow frequency range around the magnetic Mie resonance of the individual particles. Mathematical analogies between dipole and magnetoinductive waves are used to reduce back-reflections thus improving the power transfer efficiency of respective particle waveguides. The proposed technique can be used to optimize the propagation of even more complex particle-based configurations.

Information Sciences, 2005

In this paper, we report that diffractionless propagation is also possible in the visible spectra... more In this paper, we report that diffractionless propagation is also possible in the visible spectral range by downscaling the slab system as well as the PC parameters. The experimentally obtained wavelengths for optimal guidance are in excellent agreement with iso-frequency calculation

Summaries of Papers Presented at the Quantum Electronics and Laser Science Conference, 2002

Low-loss waveguiding around sharp bends is a key task in microoptics. A coupled-defect waveguide ... more Low-loss waveguiding around sharp bends is a key task in microoptics. A coupled-defect waveguide is able to perform much better at sharp bends than a channel waveguide. It also can enhance considerably the efficiency of second harmonic generation due to the low effective group velocity. Coupled-defect optical waveguides are a superlattice or superstructure consisting of original and modified unit cells

Nonlinear Guided Waves and Their Applications, 2004

2011 Conference on Lasers and Electro Optics Europe and 12th European Quantum Electronics Conference, 2011

A unique feature of superfluidity is the frictionless flow below a critical velocity. This was fi... more A unique feature of superfluidity is the frictionless flow below a critical velocity. This was first pointed out by L. D. Landau who argued that only above the speed of sound the excitations of linear or sound waves is energetically favoured (1) leading to a finite drag and to a break down of superfluidity. The superfluid motion of a dilute

2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE/EQEC), 2011

A unique feature of superfluidity is the frictionless flow below a critical velocity. This was fi... more A unique feature of superfluidity is the frictionless flow below a critical velocity. This was first pointed out by L. D. Landau who argued that only above the speed of sound the excitations of linear or sound waves is energetically favoured (1) leading to a finite drag and to a break down of superfluidity. The superfluid motion of a dilute

Quantum Electronics and Laser Science Conference Technical Digest Postconference Edition Tops Vol 40, May 12, 2000

Summary form only given. Waveguide arrays are regarded as key components in future steering and r... more Summary form only given. Waveguide arrays are regarded as key components in future steering and routing schemes, because they allow us to distribute signals between many different channels. Therefore several present experimental activities have focused on the formation and dynamics of discrete solitons. AlGaAs samples were operated below half the bandgap to employ the focusing Kerr nonlinearity. For single-mode waveguides

Nonlinear Guided Waves and Their Applications, 2004

ABSTRACT We introduce an analytical approach which permits to identify domains of existence in pa... more ABSTRACT We introduce an analytical approach which permits to identify domains of existence in parameter space of discrete cavity solitons. We demonstrate the performance of the approach for solitons in an array of quadratically nonlinear cavities.

Nonlinear Guided Waves and Their Applications, 2005

ABSTRACT We report for the first time on the existence of dissipative lattice solitons in a quadr... more ABSTRACT We report for the first time on the existence of dissipative lattice solitons in a quadratically nonlinear cavity with a periodic modulation of the refractive index. We observe various localized structures, in particular multiband solitons.

Physical Review Letters, 2004

ACS Photonics, 2016

The ability to confine and manipulate light below the diffraction limit is a major goal of future... more The ability to confine and manipulate light below the diffraction limit is a major goal of future multifunctional optoelectronic/plasmonic systems. Here, we demonstrate the design and realization of a tunable and localized electrical source of excitons coupled to surface plasmons based on a polymer light-emitting field-effect transistor (LEFET). Gold nanorods that are integrated into the channel support localized surface plasmons and serve as nanoantennas for enhanced electroluminescence. By precise spatial control of the near-infrared emission zone in the LEFET via the applied voltages the near-field coupling between electrically generated excitons and the nanorods can be turned on or off as visualized by a change of electroluminescence intensity. Numerical calculations and spectroscopic measurements corroborate significant local electroluminescence enhancement due to the high local density of photonic states in the vicinity of the gold nanorods. Importantly, the integration of plasmonic nanostructures hardly influences the electrical performance of the LEFETs, thus, highlighting their mutual compatibility in novel active plasmonic devices.

Nonlinear Optics: Materials, Fundamentals and Applications, 2000

Physical Review Letters, Oct 1, 2010

We experimentally study the impact of intrinsic and extrinsic curvature of space on the evolution... more We experimentally study the impact of intrinsic and extrinsic curvature of space on the evolution of light. We show that the topology of a surface matters for radii of curvature comparable with the wavelength, whereas for macroscopically curved surfaces only intrinsic curvature is relevant. On a surface with constant positive Gaussian curvature we observe periodic refocusing, self-imaging, and diffractionless propagation. In contrast, light spreads exponentially on surfaces with constant negative Gaussian curvature. For the first time we realized two beam interference in negatively curved space.

Optical Design and Engineering II, 2005

For gaining a deeper understanding of the diffraction processes that take place in deep dielectri... more For gaining a deeper understanding of the diffraction processes that take place in deep dielectric transmission gratings, a phenomenological explanation has been developed on the basis of a modal field, which propagates vertically through the grating region. The excitation of these modes by the incident wave, their propagation constants and how they couple to the diffraction orders determines the diffraction efficiency of the transmitted orders. The explicit modal analysis discloses the description of the highly efficient diffraction for polarized or unpolarized light by a very simple interference mechanism, which will be the subject of this paper.

Physical Review B

Lossless propagation of longitudinal magnetic dipole waves along chains of high-index subwaveleng... more Lossless propagation of longitudinal magnetic dipole waves along chains of high-index subwavelength particles is predicted for a narrow frequency range around the magnetic Mie resonance of the individual particles. Mathematical analogies between dipole and magnetoinductive waves are used to reduce back-reflections thus improving the power transfer efficiency of respective particle waveguides. The proposed technique can be used to optimize the propagation of even more complex particle-based configurations.

Information Sciences, 2005

In this paper, we report that diffractionless propagation is also possible in the visible spectra... more In this paper, we report that diffractionless propagation is also possible in the visible spectral range by downscaling the slab system as well as the PC parameters. The experimentally obtained wavelengths for optimal guidance are in excellent agreement with iso-frequency calculation

Summaries of Papers Presented at the Quantum Electronics and Laser Science Conference, 2002

Low-loss waveguiding around sharp bends is a key task in microoptics. A coupled-defect waveguide ... more Low-loss waveguiding around sharp bends is a key task in microoptics. A coupled-defect waveguide is able to perform much better at sharp bends than a channel waveguide. It also can enhance considerably the efficiency of second harmonic generation due to the low effective group velocity. Coupled-defect optical waveguides are a superlattice or superstructure consisting of original and modified unit cells

Nonlinear Guided Waves and Their Applications, 2004