A5054444212- Spectroscopy and Laser Applications
- Photonic and Optical Devices
- Terahertz technology and applications
- Semiconductor Quantum Structures and Devices
- Electron and X-Ray Spectroscopy Techniques
- Silicon Nanostructures and Photoluminescence
- Photocathodes and Microchannel Plates
- Advanced Semiconductor Detectors and Materials
- Planetary Science and Exploration
- Advanced Electron Microscopy Techniques and Applications
- Laser-induced spectroscopy and plasma
- Particle Accelerators and Free-Electron Lasers
- Advanced Chemical Physics Studies
- Quantum and electron transport phenomena
- Silicon and Solar Cell Technologies
- Semiconductor materials and devices
- Semiconductor materials and interfaces
- Ultrasonics and Acoustic Wave Propagation
- Phase-change materials and chalcogenides
- Calibration and Measurement Techniques
- Advancements in Photolithography Techniques
- Image Processing and 3D Reconstruction
- Diamond and Carbon-based Materials Research
- Gyrotron and Vacuum Electronics Research
- Spectroscopy and Quantum Chemical Studies
FELIX Laboratory
2020-2024
Radboud University Nijmegen
2020-2024
Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)
2012-2020
University of Central Florida
2020
Institute for Physics of Microstructures
2020
University of Leeds
2020
Delft University of Technology
2020
Scuola Normale Superiore
2020
Istituto Nanoscienze
2017-2020
Humboldt-Universität zu Berlin
2015-2018
Abstract Semiconductor heterostructures have enabled a great variety of applications ranging from GHz electronics to photonic quantum devices. While nonlinearities play central role for cutting-edge functionality, they require strong field amplitudes owing the weak light-matter coupling electronic resonances naturally occurring materials. Here, we ultrastrongly couple intersubband transitions semiconductor wells mode metallic cavity in order custom-tailor population and polarization dynamics...
The low temperature ($T$ = 5--40 K) capture of free electrons into hydrogenlike antimony centers in germanium has been studied by a time-resolving experiment using the electron laser FELBE. analysis pump-probe signal reveals typical time about 1.7 ns that decreases with pump energy to less than 1 while number ionized donors increases. dependence on pump-pulse is well described an acoustic phonon-assisted process. In cases when (i) significant conduction band (flux densities larger 5...
Silicon-based laser sources could bring tremendous advances to science and technology. But, generation in pure silicon is fundamentally forbidden. Now scientists demonstrate experimentally the feasibility of boron-doped silicon.
The recombination times of photo-excited free charge carriers in heavily doped and highly compensated germanium are studied by a time-resolved pump-probe experiment at frequency ∼3 THz. dominant dopant the samples is either antimony (n-Ge:Ga:Sb) or gallium (p-Ge:Sb:Ga) with compensating doping levels close to 100%. time measured our technique varies between 30 300 ps. It decreases increasing pump pulse energy compensation due high concentrations Coulomb centers. low powers up ten shorter...
The measurement of the wavefront a terahertz (THz) beam is essential for development any optical instrument operating at THz frequencies. We have realized Hartmann sensor frequency range. based on an aperture plate consisting regular square pattern holes and microbolometer camera. performance demonstrated by characterizing emitted quantum-cascade laser. determined agrees well with that expected from Gaussian-shaped beam. spatial resolution 1 mm, single-wavefront takes less than s.
Subnanosecond dynamics of optically excited electrons bound to states neutral magnesium donor centers in silicon has been investigated. Lifetimes nonequilibrium have derived from the decay differential transmission at photon energies matching intracenter and impurity-to-conduction band transitions. In contrast hydrogenlike shallow donors silicon, significantly longer lifetimes observed. This indicates weaker two-phonon off-resonant interactions dominate relaxation processes...
The low‐temperature capture processes of non‐equilibrium holes into gallium acceptors in moderately doped p‐germanium ( N A ≈ 2 × 10 15 cm −3 ) has been investigated by a single‐color pump–probe experiment using the free electron laser FELBE. time decreases with increasing average photon flux density excitation pulse from about 10.9 ns (at ∼1.2 24 −2 s −1 to (∼2 26 ). Relaxation inside valence band is almost independent on pump light intensity and its characteristic 200 ps. In Addition,...
We report on an optically pumped laser where photons are simultaneously generated by population inversion and stimulated Raman scattering in the same active medium, namely crystalline silicon doped bismuth (Si∶Bi). The medium utilizes three electronic levels: ground state [|1⟩: 1s(A1) Si∶Bi], upper [|3⟩: 2p±] lower [|2⟩: 1s(E)] levels. |1⟩↔|3⟩ |2⟩↔|3⟩ transitions allowed |1⟩↔|2⟩ transition is active. Lasing based occurs between states |3⟩ |2⟩, while benefits from Raman-active transition. At...
Abstract All-optical schemes for switching magnetization offer a pathway towards the creation of more advanced data-storage technologies, both in terms recording speed and energy-efficiency. It has previously been shown that picosecond-long optical pulses with central frequencies ranging between 12 30 THz are capable driving magnetic yttrium-iron-garnet films, provided excitation frequency matches characteristic longitudinal phonons. Here, we explore how phononic mechanism three distinct...
Transient-type stimulated emission in the terahertz (THz) frequency range has been achieved from phosphorus doped silicon crystals under optical excitation by a few-picosecond-long pulses generated infrared free electron lasers FELIX and CLIO. The analysis of lasing threshold spectra indicates that occurs due to combined population inversion based Raman scattering. Giant gain obtained optically pumped large THz cross sections intracenter impurity transitions resonant electronic...
We present the results of first systematic "round-robin" comparison far-infrared transmittance spectra measurements, which was performed by five laboratories and piloted Physikalisch-Technische (PTB). The four different samples were measured participating in 600 cm-1 to 10 range (16.67 µm 1000 µm) a blind comparison. Different types instruments, Fourier transform infrared (FT-IR) spectrometers Michelson type laser radiation-based system used for measurements. FT-IR are most popular commonly...