313 citations · 1.1k across the 22 of their papers we have counts for
22 papers
Ultrafast Relaxation Dynamics of Spin-Density Wave Order in BaFeAs under High Pressures
Ivan Fotev, Stephan Winnerl, Saicharan Aswartham +5
BaFeAs is the parent compound for a family of iron-based high-temperature superconductors as well as a prototypical example of the spin-density wave (SDW) system. In this s…
Ultra-Broadband Visible and Infrared Light Generation Driven by Far Infrared Light in the Broad Region from 8μm to 240μm
Nils W. Rosemann, Robin C. Döring, Eike Dornsiepen +12
The most commonly used nonlinear optical process is the conversion of infrared light at 1064nm to green light at 532nm, as performed in common laser pointers. However, more relevan…
Pump-induced terahertz anisotropy in bilayer graphene
Angelika Seidl, Roozbeh Anvari, Marc M. Dignam +5
We investigate the intraband nonlinear dynamics in doped bilayer graphene in the presence of strong, linearly-polarized, in-plane terahertz fields. We perform degenerate pump-probe…
Enhanced trion emission in monolayer MoSe2 by constructing a type-I van der Waals heterostructure
Juanmei Duan, Phanish Chava, Mahdi Ghorbani-Asl +10
Trions, quasi-particles consisting of two electrons combined with one hole or of two holes with one electron, have recently been observed in transition metal dichalcogenides (TMDCs…
Optical Kerr nonlinearity and multi-photon absorption of DSTMS measured by Z-scan method
Jiang Li, Rakesh Rana, Liguo Zhu +3
We investigate the optical Kerr nonlinearity and multi-photon absorption (MPA) properties of DSTMS excited by femtosecond pulses at a wavelengths of 1.43 μm, which is optimal for t…
Silicon-based Intermediate-band Infrared Photodetector realized by Te Hyperdoping
Mao Wang, Eric García-Hemme, Yonder Berencén +7
Si-based photodetectors satisfy the criteria of low-cost and environmental-friendly, and can enable the development of on-chip complementary metal-oxide-semiconductor (CMOS)-compat…
Nonlinear Charge Transport in InGaAs Nanowires at Terahertz Frequencies
Rakesh Rana, Leila Balaghi, Ivan Fotev +4
We probe the electron transport properties in the shell of GaAs/In0.2Ga0.8As core/shell nanowires at high electric fields using optical pump / THz probe spectroscopy with broadband…
Photoluminescence dynamics in few-layer InSe
Tommaso Venanzi, Himani Arora, Stephan Winnerl +10
We study the optical properties of thin flakes of InSe encapsulated in hBN. More specifically, we investigate the photoluminescence (PL) emission and its dependence on sample thick…
Mode-locked ultrashort pulses from an 8 m wavelength semiconductor laser
Johannes Hillbrand, Nikola Opacak, Marco Piccardo +4
Quantum cascade lasers (QCL) have revolutionized the generation of mid-infrared light. Yet, the ultrafast carrier transport in mid-infrared QCLs has so far constituted a seemingly…
Up to 70 THz bandwidth from implanted Ge photoconductive antenna excited by a fibre laser
Abhishek Singh, Alexej Pashkin, Stephan Winnerl +6
Phase-stable electromagnetic pulses in the THz frequency range offer several unique capabilities in time-resolved spectroscopy. However, the diversity of their application is limit…
Carrier dynamics in graphene: ultrafast many-particle phenomena
Ermin Malic, Torben Winzer, Florian Wendler +10
Graphene is an ideal material to study fundamental Coulomb- and phonon-induced carrier scattering processes. Its remarkable gapless and linear band structure opens up new carrier r…
Non-thermal nature of photo-induced insulator-to-metal transition in NbO
Rakesh Rana, J. Michael Klopf, Jörg Grenzer +3
We study the photo-induced metallization process in niobium dioxide NbO. This compound undergoes the thermal insulator-to-metal transition at the remarkably high temperature of…
Up to 40 % reduction of the GaAs band gap energy via strain engineering in core/shell nanowires
L. Balaghi, G. Bussone, R. Grifone +7
The great possibilities for strain engineering in core/shell nanowires have been explored as an alternative route to tailor the properties of binary III-V semiconductors without ch…
Symmetry-breaking supercollisions in Landau-quantized graphene
Florian Wendler, Martin Mittendorff, Jacob C. König-Otto +8
Recent pump-probe experiments performed on graphene in a perpendicular magnetic field have revealed carrier relaxation times ranging from picoseconds to nanoseconds depending on th…
Infrared nanoscopy down to liquid helium temperatures
D. Lang, J. Döring, T. Nörenberg +7
We introduce a scattering-type scanning near-field infrared microscope (s-SNIM) for the local scale near- field sample analysis and spectroscopy from room (RT) down to liquid heliu…
Ultrafast Carrier Dynamics in VO across the Pressure-Induced Insulator-to-Metal Transition
Johannes M. Braun, Harald Schneider, Manfred Helm +5
We utilize near-infrared pump and mid-infrared probe spectroscopy to investigate the ultrafast electronic response of pressurized VO. Distinct pump-probe signals and a pumping…
Doubly dressed bosons - exciton-polaritons in a strong terahertz field
B. Piętka, N. Bobrovska, D. Stephan +12
We demonstrate the existence of a novel quasiparticle: an exciton in a semiconductor doubly dressed with two photons of different wavelengths: near infrared cavity photon and terah…
Anisotropy of excitation and relaxation of photogenerated Dirac electrons in graphene
Martin Mittendorff, Torben Winzer, Ermin Malic +6
We investigate the polarization dependence of the carrier excitation and relaxation in epitaxial multilayer graphene. Degenerate pump-probe experiments with a temporal resolution o…
Ultrafast graphene-based broadband THz detector
Martin Mittendorff, Stephan Winnerl, Josef Kamann +4
We present an ultrafast graphene-based detector, working in the THz range at room temperature. A logarithmic-periodic antenna is coupled to a graphene flake that is produced by exf…
Universal phase relation between longitudinal and transverse fields observed in focused terahertz beams
S. Winnerl, R. Hubrich, M. Mittendorff +2
We directly observe longitudinal electromagnetic fields in focused freely propagating terahertz beams of radial and linear polarization. In accordance with theory, the longitudinal…
Observation of Coulomb-Assisted Dipole-Forbidden Intraexciton Transitions in Semiconductors
W. D. Rice, J. Kono, S. Zybell +14
We use terahertz pulses to induce resonant transitions between the eigenstates of optically generated exciton populations in a high-quality semiconductor quantum-well sample. Monit…
Carrier dynamics in epitaxial graphene close to the Dirac point
Stephan Winnerl, Milan Orlita, Paulina Plochocka +10
We study the carrier dynamics in epitaxially grown graphene in the range of photon energies from 10 - 250 meV. The experiments complemented by microscopic modeling reveal that the…