Journal ArticleDOI
Simultaneous time and wavelength resolved spectroscopy under two-colour near infrared and terahertz excitation
Jayeeta Bhattacharyya,Martin Wagner,S. Zybell,S. Winnerl,D. Stehr,Manfred Helm,Harald Schneider +6 more
TLDR
This work uses table-top Ti:sapphire lasers and a free-electron laser emitting ps pulses as excitation sources and a streak camera coupled to a spectrometer for detection for time and wavelength resolved spectroscopy.Abstract:
Time and wavelength resolved spectroscopy requires optical sources emitting very short pulses and a fast detection mechanism capable of measuring the evolution of the output spectrum as a function of time. We use table-top Ti:sapphire lasers and a free-electron laser (FEL) emitting ps pulses as excitation sources and a streak camera coupled to a spectrometer for detection. One of the major aspects of this setup is the synchronization of pulses from the two lasers which we describe in detail. Optical properties of the FEL pulses are studied by autocorrelation and electro-optic sampling measurements. We discuss the advantages of using this setup to perform photoluminescence quenching in semiconductor quantum wells and quantum dots. Carrier redistribution due to pulsed excitation in these heterostructures can be investigated directly. Sideband generation in quantum wells is also studied where the intense FEL pulses facilitate the detection of the otherwise weak nonlinear effect.read more
Citations
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Journal ArticleDOI
Ultrafast graphene-based broadband THz detector
Martin Mittendorff,Stephan Winnerl,Josef Kamann,Jonathan Eroms,Dieter Weiss,Harald Schneider,Manfred Helm +6 more
TL;DR: In this article, an ultrafast graphene-based detector is presented, working in the THz range at room temperature, with a logarithmic-periodic antenna coupled to a graphene flake that is produced by exfoliation on SiO2.
Journal ArticleDOI
Ultrafast graphene-based broadband THz detector
Martin Mittendorff,Stephan Winnerl,Josef Kamann,Jonathan Eroms,Dieter Weiss,Harald Schneider,Manfred Helm +6 more
TL;DR: In this article, a logarithmic-periodic antenna is coupled to a graphene flake that is produced by exfoliation on SiO2, and the detector rise time is 50 ps in the wavelength range from 30 um to 220 um.
Journal ArticleDOI
Note: Three wavelengths near-infrared spectroscopy system for compensating the light absorbance by water
TL;DR: A wireless functional near-infrared spectroscopy system that detects not only the concentration changes of oxy- and deoxy-hemoglobin during mental activity but also that of water (H2O) and implements a water- absorption correction algorithm that improves the HbO and HbR signal strengths during an arithmetic task.
Journal ArticleDOI
Time-resolved spectroscopy on epitaxial graphene in the infrared spectral range: relaxation dynamics and saturation behavior
Stephan Winnerl,F. Göttfert,Martin Mittendorff,Martin Mittendorff,Harald Schneider,Manfred Helm,Manfred Helm,Torben Winzer,Ermin Malic,Andreas Knorr,Milan Orlita,Milan Orlita,Marek Potemski,Mike Sprinkle,Claire Berger,W. A. de Heer +15 more
TL;DR: The saturation of pump-induced bleaching of graphene is studied and a quadratic dependence of the saturation fluence on the pump photon energy in the infrared spectral range is revealed.
Journal ArticleDOI
Ultra-fast transistor-based detectors for precise timing of near infrared and THz signals
TL;DR: This paper presents the first detector capable to resolve both near-infrared and Terahertz pulses at the same time, operated at room temperature, and its dynamic range is as large as 65±3dB/Hz, enabling applications in a large variety of experiments and setups.
References
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Journal ArticleDOI
Ultralong Dephasing Time in InGaAs Quantum Dots
Paola Borri,Wolfgang Werner Langbein,S. Schneider,Ulrike Woggon,Roman Sellin,D. Ouyang,Dieter Bimberg +6 more
TL;DR: Between 7 and 100 K the polarization decay has two distinct components resulting in a non-Lorentzian line shape with a lifetime-limited zero-phonon line and a broadband from elastic exciton-acoustic phonon interactions.
Journal ArticleDOI
Ultrafast Carrier Dynamics in Graphite
TL;DR: Optical pump-probe spectroscopy with 7-fs pump pulses and a probe spectrum wider than 0.7 eV reveals the ultrafast carrier dynamics in freestanding thin graphite films and discerns for the first time a rapid intraband carrier equilibration within 30 fs, leaving the system with separated electron and hole chemical potentials.
Journal ArticleDOI
Optical investigation of Bloch oscillations in a semiconductor superlattice.
Jochen Feldmann,Karl Leo,Jagdeep Shah,David A. B. Miller,J. E. Cunningham,Torsten Meier,G. von Plessen,A. Schulze,P. Thomas,S. Schmitt-Rink +9 more
TL;DR: In this paper, optical dephazing of Wannier-Stark ladder excitations in a semiconductor superlattice was studied by means of transient degenerate four-wave mixing.
Journal ArticleDOI
Mode-locked pulses from mid-infrared quantum cascade lasers.
C. Y. Wang,Lyuba Kuznetsova,Vasileios-Marios Gkortsas,Laurent Diehl,Franz X. Kärtner,Mikhail A. Belkin,Alexey Belyanin,Xiaofeng Li,Donhee Ham,Harald Schneider,P. D. Grant,C. Y. Song,Soufien Haffouz,Z. R. Wasilewski,H. C. Liu,Federico Capasso +15 more
TL;DR: This study reports the unequivocal demonstration of midinfrared mode-locked pulses from quantum cascade lasers generated by actively modulating the current and hence the gain of an edge-emitting quantum cascade laser (QCL).
Journal ArticleDOI
Stable mode-locked pulses from mid-infrared semiconductor lasers
C. Y. Wang,Lyuba Kuznetsova,Vasileios-Marios Gkortsas,Laurent Diehl,F. X. Kaertner,Mikhail A. Belkin,A. A. Belyanin,Xiangping Li,Donhee Ham,Harald Schneider,P. D. Grant,C. Y. Song,S. Haffouz,Z. R. Wasilewski,H. C. Liu,Federico Capasso +15 more
TL;DR: In this article, mode-locking dynamics in a small section of an edge-emitting quantum cascade laser (QCL) were modeled and simulated based on the Maxwell-Bloch equations in an open two-level system.