A5030017389- Plasmonic and Surface Plasmon Research
- Gold and Silver Nanoparticles Synthesis and Applications
- Laser-Plasma Interactions and Diagnostics
- Strong Light-Matter Interactions
- Near-Field Optical Microscopy
- 2D Materials and Applications
- Advanced X-ray Imaging Techniques
- Photonic and Optical Devices
- Random lasers and scattering media
- Molecular Junctions and Nanostructures
- Metamaterials and Metasurfaces Applications
- Laser-Matter Interactions and Applications
- Photonic Crystals and Applications
- Orbital Angular Momentum in Optics
- Advanced Fluorescence Microscopy Techniques
- Advanced Electron Microscopy Techniques and Applications
- Perovskite Materials and Applications
- Quantum Information and Cryptography
- Spectroscopy and Quantum Chemical Studies
- Quantum and electron transport phenomena
- Nonlinear Optical Materials Studies
- Microwave Engineering and Waveguides
- Integrated Circuits and Semiconductor Failure Analysis
- Optical Coatings and Gratings
- X-ray Diffraction in Crystallography
Carl von Ossietzky Universität Oldenburg
2015-2024
University of Applied Sciences Emden Leer
2022-2023
CeNTech
2006-2010
University of Münster
2004-2007
Plasmonic nanoantennas are versatile tools for coherently controlling and directing light on the nanoscale. For these antennas, current fabrication techniques such as electron beam lithography (EBL) or focused ion (FIB) milling with Ga+-ions routinely achieve feature sizes in 10 nm range. However, they suffer increasingly from inherent limitations when a precision of single nanometers down to atomic length scales is required, where exciting quantum mechanical effects expected affect...
Transition metal dichalcogenides (TMDs) are quantum confined systems with interesting optoelectronic properties, governed by Coulomb interactions in the monolayer (1L) limit, where strongly bound excitons provide a sensitive probe for many-body interactions. Here, we use two-dimensional electronic spectroscopy (2DES) to investigate and their dynamics 1L-WS
Solid-state single-photon sources are central building blocks in quantum information processing. Atomically thin crystals have emerged as of nonclassical light; however, they perform below the state-of-the-art devices based on volume crystals. Here, we implement a bright source an atomically sheet WSe2 coupled to tunable optical cavity liquid-helium-free cryostat without further need for active stabilization. Its performance is characterized by high purity (g(2)(0) = 4.7 ± 0.7%) and...
Structural diffraction analysis of an anilino squaraine with branched isobutyl side chains shows crystallization into two polymorphic structures in the bulk and spin-casted thin films. We observe multipeaked pleochroic absorption spectra being blue-(red)-shifted for monoclinic (orthorhombic) polymorph. understand packing as Coulombic molecular H-(J)-aggregates supporting Davydov splitting. Pictures projected components oriented films fit well to polarization resolved spectro-microscopy...
Enlarging exciton coherence lengths in molecular aggregates is critical for enhancing the collective optical and transport properties of thin film nanostructures or devices. We demonstrate that length squaraine can be increased from 10 to 24 units at room temperature when preparing aggregated on a metallic rather than dielectric substrate. Two-dimensional electronic spectroscopy measurements reveal much lower degree inhomogeneous line broadening gold film, pointing reduced disorder. The...
We demonstrate an essentially dispersion-free and diffraction-limited focusing of few-cycle laser pulses through all-reflective microscope objectives. By transmitting 6-fs-pulses from a Ti:sapphire oscillator 0.5 NA objective, we reach focus with beam diameter 1.0 µm, preserving the time structure pulses. The temporal spatial pulse profile is recorded simultaneously using novel tip-enhanced electron emission autocorrelator, indicating focal volume these only 1.8 µm3. anticipate that...
Metallic nanostructures can transport electromagnetic fields in the form of surface plasmon polariton (SPP) excitations, focus them into nanometric spots, and transfer to nearby by near-field coupling. This provides a basic functionality for designing new plasmonic devices that greatly enhance light–matter coupling facilitate ultrafast efficient all-optical switching on nanoscale. Here, we study prototypical device geometry, bow-tie antenna equipped with curved line gratings, light across...
We report the first observation of coupling strong optical near fields to wavepackets free, 100 eV electrons with <50 fs temporal resolution in an ultrafast point-projection microscope. Optical are created by excitation a thin, nanometer-sized Yagi-Uda antenna, 20 near-infrared laser pulses. Phase matching between and is achieved due spatial confinement antenna field. Energy-resolved projection images recorded pump-electron probe scheme. show that phase modulation electron transverse-field...
Abstract A combination of helium- and gallium-ion beam milling together with a fast reliable sketch-and-peel technique is used to fabricate gold nanorod dimer antennas an excellent quality factor gap distances less than 6 nm. The high fabrication the compared conventional ion proven by polarisation-resolved linear dark-field spectromicroscopy isolated antennas. We demonstrate strong coupling two antenna arms for both techniques, more 14, close theoretical limit, sketch-and-peel–produced only...
Organic exciton-polaritons, which arise from the strong light-matter coupling between excitons in organic molecules and cavity photons, have emerged as a versatile platform for investigation of polariton lasing, Bose-Einstein condensation many-body phenomena at ambient conditions. Here, we study exciton-polaritons fluorescent protein-filled microcavities with elliptical cross-sections. The structural anisotropy these cavities yields distinct optical polarization splitting, investigate both...
The nonlinear optical properties of thin ZnO film are studied using interferometric autocorrelation (IFRAC) microscopy. Ultrafast, below-bandgap excitation with 6-fs laser pulses at 800 nm focused to a spot size 1 µm results in two emission bands the blue and blue-green spectral region distinctly different coherence properties. We show that an analysis wavelength-dependence interference fringes IFRAC signal allows for unambiguous assignment these as coherent second harmonic incoherent,...
Surface plasmon polaritons (SPPs) are short-lived evanescent waves that can confine light at the surface of metallic nanostructures and transport energy over mesoscopic distances. They may be used to generate process information encoded as optical signals realize nanometer-scale ultrafast all-optical circuitry. The propagation properties these SPPs defined by geometry composition nanostructure. Due their short, femtosecond lifetimes, it has so far proven difficult track this in time domain...
Chiral plasmonic nanostructures will be of increasing importance for future applications in the field nano optics and metamaterials. Their sensitivity to incident circularly polarized light combination with ability extreme electromagnetic localization renders them ideal candidates chiral sensing all-optical information processing. Here, resonant modes single helices are investigated. We find that a helix can efficiently excited both equal opposite handedness relative helix. An analytic model...
We report a drastic increase of the damping time plasmonic eigenmodes in resonant bull's eye (BE) nanoresonators to more than 35 fs. This is achieved by tailoring groove depth resonator and coupling confined field aperture an extended mode such that spatial coherence preserved over distances 10 μm. Experimentally, this demonstrated probing plasmon dynamics at level using broadband spectral interferometry. The nanoresonator allows us efficiently concentrate incident inside central BE tailor...
The strong coherent coupling of quantum emitters to vacuum fluctuations the light field offers opportunities for manipulating optical and transport properties nanomaterials, with potential applications ranging from ultrasensitive all-optical switching creating polariton condensates. Often, ubiquitous decoherence processes at ambient conditions limit these couplings such short time scales that dynamics interacting system remains elusive. Prominent examples are strongly coupled exciton-plasmon...
We propose an approach of steering the second harmonic (SH) emission from a single plasmonic structure, through local excitations plasmon. The proposed idea is confirmed experimentally, by adjusting incident beam position at fundamental frequency, on antenna. A significant directivity change ( ± 52°) for SH observed with submicrometer adjustment 250 nm) excitation position, over broadband frequencies. Providing simple method controlling frequency-converted light, our paves way to new design...
Abstract Despite the plethora of intriguing phenomena observed in heterostructure stacks 2D transition metal dichalcogenide (2D‐TMDC) flakes, their application functional devices is still hampered due to lack reliable growth methodologies for large‐area heterostructures. Here, a scalable process obtaining as‐grown di‐chalcogenide heterostructures by combination atomic layer deposition monolayer MoS 2 and solution‐based processing ultrathin WS presented. Spatially uniform optical electrical...
Femtosecond laser excitation and density functional theory reveal site vibrational state specificity in neutral atomic hydrogen desorption from graphite induced by multiple electronic transitions. Multimodal velocity distributions witness the participation of ortho para pair states chemisorbed process. Very slow velocities 700 $400\text{ }\text{ }{\mathrm{ms}}^{\ensuremath{-}1}$ for H D atoms are associated with out highest a barrierless potential.