Stefan Nolte

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Topological insulators are a new phase of matter, with the striking property that conduction of electrons occurs only on their surfaces. In two dimensions, electrons on the surface of a topological insulator are not scattered despite defects and disorder, providing robustness akin to that of superconductors. Topological insulators are predicted to have(More)
Graphene, a two-dimensional honeycomb lattice of carbon atoms, has been attracting much interest in recent years. Electrons therein behave as massless relativistic particles, giving rise to strikingly unconventional phenomena. Graphene edge states are essential for understanding the electronic properties of this material. However, the coarse or impure(More)
The aim of the present study was to investigate the influence of reduced plantar sensation on pressure distribution patterns during gait of 40 healthy subjects (25.3+/-3.3 yr, 70.8+/-10.6 kg and 176.5+/-7.8 cm) with no history of sensory disorders. Plantar sensation in the subjects was reduced by using an ice immersion approach, and reduced sensitivity was(More)
We report on a novel ytterbium-doped fiber design that combines the advantages of rod and fiber gain media. The fiber design has outer dimensions of a rod laser, meaning a diameter in the range of a few millimeters and a length of just a few tens of centimeters, and includes two important waveguide structures, one for pump radiation and one for laser(More)
We report on a 2.3 m long air-clad ytterbium-doped large-modearea photonic crystal fiber laser generating up to 80 W output power with a slope efficiency of 78%. Single transverse mode operation is achieved with a mode-field area of 350 microm2. No thermo-optical limitations are observed at the extracted ~35W/m, therefore such fibers allow scaling to even(More)
We investigate dynamic localization in curved femtosecond (fs) laser written waveguide arrays. The light propagation inside the array is directly observed by monitoring fluorescence of color centers induced during the fs writing process. In addition to monochromatic excitation the spectral response of the arrays is investigated by launching white light(More)
We report the observation of nonlinearity-induced broadening of resonances in dynamically modulated directional couplers. When the refractive index of the guiding channels in the coupler is harmonically modulated along the propagation direction and is out-of-phase in two channels, coupling can be completely inhibited at resonant modulation frequencies. We(More)
OBJECTIVE In this feasibility study, we investigate possible femtosecond laser thrombolysis. BACKGROUND DATA Because of low pulse energies, femtosecond laser surgery inherently minimizes side effects on the surrounding tissue. Moreover, current femtosecond laser sources as well as fiber technology allow consideration of catheter-based treatments. (More)
The observation of discrete spatial solitons in fs laser written waveguide arrays in fused silica is reported for the .rst time. The fs writing process permits the speci.c setting of the linear and nonlinear guiding properties of the waveguides. The results in this paper reveal a new avenue for the fabrication of various nonlinear optical devices.
We report on an air-clad large-core single-transverse-mode ytterbium-doped photonic crystal fiber with a mode-field-diameter of 35 microm, corresponding to a mode-field-area of ~1000 microm(2). In a first experiment this fiber is used to amplify 10-ps pulses to a peak power of 60 kW without significant spectral broadening due to self-phase modulation(More)