Zobrazeno 1 - 10
of 2 784
pro vyhledávání: '"H T Grahn"'
Publikováno v:
AIP Advances, Vol 12, Iss 8, Pp 085122-085122-5 (2022)
We have investigated high-performance GaAs/AlAs terahertz (THz) quantum-cascade lasers (QCLs) with respect to the long-term stability of their operating parameters. The output power of lasers that contain an additional, thick AlAs refractive-index co
Externí odkaz:
https://doaj.org/article/c72fd122cca14144adaa9c1d54fb45da
Autor:
X Lü, B Röben, K Biermann, J R Wubs, U Macherius, K-D Weltmann, J H van Helden, L Schrottke, H T Grahn
We report on terahertz (THz) quantum-cascade lasers (QCLs) based on GaAs/AlAs heterostructures, which exhibit single-mode emission at 3.360, 3.921, and 4.745 THz. These frequencies are in close correspondence to fine-structure transitions of Al atoms
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::d0f591cb82820fd3c7ef3cb869421056
Autor:
R. Voigt, M. Wienold, D. Jayasankar, V. Drakinskiy, J. Stake, P. Sobis, L. Schrottke, X. Lü, H. T. Grahn, H.-W. Hübers
Publikováno v:
Optics Express. 31:13888
We demonstrate the frequency stabilization of a terahertz quantum-cascade laser (QCL) to the Lamb dip of the absorption line of a D2O rotational transition at 3.3809309 THz. To assess the quality of the frequency stabilization, a Schottky diode harmo
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::0eb99d2bb1c7fe51e424ceba9c15a5d7
https://doi.org/10.1364/oe.483883
https://doi.org/10.1364/oe.483883
Publikováno v:
AIP Advances, Vol 6, Iss 6, Pp 065104-065104-6 (2016)
The far-field distribution of the emission intensity of terahertz (THz) quantum-cascade lasers (QCLs) frequently exhibits multiple lobes instead of a single-lobed Gaussian distribution. We show that such multiple lobes can result from self-interferen
Externí odkaz:
https://doaj.org/article/4705667e140c43dcbb338ba9ee14ebc7
Autor:
J R Wubs, U Macherius, K-D Weltmann, X Lü, B Röben, K Biermann, L Schrottke, H T Grahn, J H van Helden
Publikováno v:
Plasma Sources Science and Technology. 32:025006
This paper describes the first implementation of terahertz (THz) quantum cascade lasers for high-resolution absorption spectroscopy on plasmas. Absolute densities of ground state atomic oxygen were directly obtained by using the fine structure transi
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::ed13128e6d3a1fda257f5fa280a4f500
https://doi.org/10.1088/1361-6595/acb815
https://doi.org/10.1088/1361-6595/acb815
Publikováno v:
Optics express. 27(4)
Near-infrared optical excitation enables wideband frequency tuning of terahertz quantum-cascade lasers. In this work, we demonstrate the feasibility of the approach for molecular laser absorption spectroscopy. We present a physical model which explai
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=pmid________::6841886a51081614d8f22a3df8c4e6b7
https://pubmed.ncbi.nlm.nih.gov/30876146
https://pubmed.ncbi.nlm.nih.gov/30876146
Publikováno v:
Optics express. 26(6)
We report on the Doppler-free saturation spectroscopy of a molecular transition at 3.3 THz based on a quantum-cascade laser and an absorption cell in a collinear pump-probe configuration. A Lamb dip with a sub-Doppler linewidth of 170 kHz is observed
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=pmid________::b4ab0ee2cf01622a9af004b406fd212b
https://pubmed.ncbi.nlm.nih.gov/29609356
https://pubmed.ncbi.nlm.nih.gov/29609356
Autor:
Martin Wienold, Kerstin Rösner, Michael Greiner-Bär, Lutz Schrottke, H. T. Grahn, Klaus Biermann, Heinz-Wilhelm Hübers, A. D. Semenov, Heiko Richter
Publikováno v:
2014 39th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz).
— We report on the development of a 4.7-THz local oscillator (LO) for the heterodyne spectrometer GREAT on SOFIA. The design of the LO and its performance in terms of output power, frequency accuracy, frequency stability, and beam profile as well a
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::669e19bf550848ba565a8fda00498185
https://doi.org/10.1109/irmmw-thz.2014.6956456
https://doi.org/10.1109/irmmw-thz.2014.6956456
Publikováno v:
physica status solidi (a). 211:736-739
We prepared {11−22} GaN layers with different thicknesses on r-plane patterned sapphire substrates (r-PSS) through metal-organic vapor phase epitaxy. In order to obtain a {11−22} GaN layer of high crystalline quality, a wide terrace was adopted f
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::fc8b46c98947dbdea9d92b62bf94daf0
https://doi.org/10.1002/pssa.201300465
https://doi.org/10.1002/pssa.201300465
Autor:
H.-W. Hübers, Lutz Schrottke, Klaus Biermann, H. T. Grahn, Michael Greiner-Bär, Heiko Richter, Martin Wienold
Publikováno v:
2015 40th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz).
The design and the performance of a 4.7-THz local oscillator (LO) for the GREAT (German REceiver for Astronomy at Terahertz frequencies) heterodyne spectrometer on SOFIA, the Stratospheric Observatory for Infrared Astronomy, are presented. The LO is
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::a661a893dd7672ac28e9e3d4ae7aa106
https://doi.org/10.1109/irmmw-thz.2015.7327877
https://doi.org/10.1109/irmmw-thz.2015.7327877