73 citations · 455 across the 28 of their papers we have counts for
30 papers
Contact-free charge carrier density determination of doped sub-μm thin cubic GaN layers with terahertz time-domain spectroscopy
Joshua Hennig, Mario F. Zscherp, Silas A. Jentsch +11
As cubic GaN is a promising material for optoelectronic applications, its layers need to be precisely doped to realize the desired properties. While contact-based methods are estab…
Mach-Zehnder based Rotational Shearing Interferometer for Non-destructive Testing using Spatial Phase-Shifting Shearography
Valentin-Johannes Bastgen, Michael Schuth, Georg von Freymann
This work introduces a novel optical setup based on a Mach-Zehnder interferometer, enabling spatial phase shifting shearography with rotational shear. The optical concept employs a…
Spatiotemporal Terahertz Emission Nanoscopy of Spintronic Photocurrents
F. Paries, R. Rouzegar, J. Cai +9
Capturing ultrafast spin and charge photocurrents on nanoscopic scales is essential for fundamental research in physics and engineering, as well as for future applications, such as…
Enhancement of magnon flux toward a Bose-Einstein condensate
Franziska Kühn, Matthias R. Schweizer, Tamara Azevedo +5
We present a combined theoretical and experimental study of angle-dependent parametric pumping of magnons in Yttrium Iron Garnet films, with a focus on the mechanisms that transfer…
Spontaneous Emergence of Phase Coherence in a quasiparticle Bose-Einstein Condensate
Malte Koster, Matthias R. Schweizer, Timo Noack +6
Since their prediction by Einstein at the dawn of quantum mechanics, Bose-Einstein condensates (BECs), owing to their property to show quantum phenomena on macroscopic scales, are…
Terahertz Quantum Imaging
Mirco Kutas, Felix Riexinger, Jens Klier +2
Quantum imaging with undetected photons spatially transfers amplitude and phase information from one spectral region of physical interest to another spectral region that is easy to…
Magnetic nutation: transient separation of magnetization from its angular momentum
Anulekha De, Julius Schlegel, Akira Lentfert +6
For nearly 90 years, precession and relaxation processes have been thought to dominate magnetization dynamics. Only recently has it been considered that, on short time scales, an i…
Wide-range resistivity characterization of semiconductors with terahertz time-domain spectroscopy
Joshua Hennig, Jens Klier, Stefan Duran +9
Resistivity is one of the most important characteristics in the semiconductor industry. The most common way to measure resistivity is the four-point probe method, which requires ph…
Local temperature control of magnon frequency and direction of supercurrents in a magnon Bose-Einstein condensate
Matthias R. Schweizer, Franziska Kühn, Victor S. L'vov +4
The creation of temperature variations in magnetization, and hence in the frequencies of the magnon spectrum in laser-heated regions of magnetic films, is an important method for s…
Dimensional Crossover in a Quantum Gas of Light
Kirankumar Karkihalli Umesh, Julian Schulz, Julian Schmitt +3
The dimensionality of a system profoundly influences its physical behaviour, leading to the emergence of different states of matter in many-body quantum systems. In lower dimension…
Broadband mode division multiplexing of OAM-modes by a micro printed waveguide structure
Julian Schulz, Georg von Freymann
A light beam carrying orbital angular momentum (OAM) is characterized by a helical phase-front that winds around the center of the beam. These beams have unique properties that hav…
Mixing Rule for Calculating the Effective Refractive Index Beyond the Limit of Small Particles
Dominic T. Meiers, Georg von Freymann
Considering light transport in disordered media, the medium is often treated as an effective medium requiring accurate evaluation of an effective refractive index. Because of its s…
Rapid-prototyping of microscopic thermal landscapes in Brillouin light scattering spectroscopy
Matthias R. Schweizer, Franziska Kühn, Malte Koster +3
Since temperature and its spatial and temporal variations affect a wide range of physical properties of material systems, they can be used to create reconfigurable spatial structur…
Fiber-tip spintronic terahertz emitters
Felix Paries, Nicolas Tiercelin, Geoffrey Lezier +12
Spintronic terahertz emitters promise terahertz sources with an unmatched broad frequency bandwidth that are easy to fabricate and operate, and therefore easy to scale at low cost.…
Coherent and incoherent magnons induced by strong ultrafast demagnetization in thin permalloy films
Anulekha De, Akira Lentfert, Laura Scheuer +4
Understanding spin dynamics on femto- and picosecond timescales offers new opportunities for faster and more efficient spintronic devices. Here, we experimentally investigate the c…
Coherent magnetization dynamics in strongly quenched Ni thin films
Akira Lentfert, Anulekha De, Laura Scheuer +4
The remagnetization process after ultrafast demagnetization can be described by relaxation mechanisms between the spin, electron, and lattice reservoirs. Thereby, collective spin e…
Initiator-free photo-crosslinkable cellulose-based resists for fabricating submicron patterns via direct laser writing
Maximilian Rothammer, Dominic T. Meiers, Maximilian Maier +2
Novel bifunctional cellulose diacetate derivatives were synthesized in order to achieve bio-based photoresists, which can be structured by two-photon absorption via direct laser wr…
Confinement of Bose-Einstein magnon condensates in adjustable complex magnetization landscapes
Matthias R. Schweizer, Alexander J. E. Kreil, Georg von Freymann +2
Coherent wave states such as Bose-Einstein condensates (BECs), which spontaneously form in an overpopulated magnon gas even at room temperature, have considerable potential for wav…
Phase-quadrature quantum imaging with undetected photons
Björn Erik Haase, Joshua Hennig, Mirco Kutas +4
Sensing with undetected photons allows access to spectral regions with simultaneous detection of photons of another region and is based on nonlinear interferometry. To obtain the f…
Electronic Phase Detection with sub-10 fs Timing Jitter for Terahertz Time-Domain Spectroscopy Systems
Felix Paries, Oliver Boidol, Georg von Freymann +1
Terahertz time-domain spectroscopy systems based on resonator-internal repetition-rate modulation, such as SLAPCOPS [12] and ECOPS [11], rely on electronic phase detectors which ar…
Towards efficient structure prediction and pre-compensation in multi-photon lithography
Nicolas Lang, Sven Enns, Julian Hering +1
Microscale 3D printing technologies have been of increasing interest in industry and research for several years. Unfortunately, the fabricated structures always deviate from the re…
Fiber-tip endoscope for optical and microwave control
Stefan Dix, Jonas Gutsche, Erik Waller +2
We present a robust, fiber based endoscope with a silver direct-laser-written (DLW) structure for radio frequency (RF) emission next to the optical fiber facet. Thereby, we are abl…
Photonic quadrupole topological insulator using orbital-induced synthetic flux
Julian Schulz, Jiho Noh, Wladimir A. Benalcazar +2
The rich physical properties of multiatomic molecules and crystalline structures are determined, to a significant extent, by the underlying geometry and connectivity of atomic orbi…
General simulation method for spontaneous parametric down- and parametric up-conversion experiments
Felix Riexinger, Mirco Kutas, Björn Haase +4
Spontaneous parametric down-conversion (SPDC) sources are an important technology for quantum sensing and imaging. We demonstrate a general simulation method, based on modeling fro…