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- Das, Lakshmi, et al.
(author)
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NiO thin films fabricated using spray-pyrolysis technique : structural and optical characterization and ultrafast charge dynamics studies
- 2024
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In: Journal of Physics D. - : Institute of Physics Publishing (IOPP). - 0022-3727 .- 1361-6463. ; 57:38
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Journal article (peer-reviewed)abstract
- Nickel (II) oxide, NiO, is a wide band gap Mott insulator characterized by strong Coulomb repulsion between d-electrons and displays antiferromagnetic order at room temperature. NiO has gained attention in recent years as a very promising candidate for applications in a broad set of areas, including chemistry and metallurgy to spintronics and energy harvesting. Here, we report on the fabrication of polycrystalline NiO using spray-pyrolysis technique, which is a deposition technique able to produce quite uniform films of pure and crystalline materials without the need of high vacuum or inert atmospheres. The composition and structure of the NiO thin films were then studied using x-ray diffraction, and atomic force and scanning electron microscopies (SEM). The phononic and magnonic properties of the NiO thin films were also studied via Raman spectroscopy, and the ultrafast electron dynamics by using optical pump probe spectroscopy. We found that the NiO samples display the same phonon and magnon excitations expected for single crystal NiO at room temperature, and that electron dynamics in our system is like those of previously reported NiO mono- and polycrystalline systems synthesized using different techniques. These results prove that spray-pyrolysis can be used as affordable and large-scale fabrication technique to synthesize strongly correlated materials for a large set of applications.
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- Fischer, Peter, et al.
(author)
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Optimization of Optical Parametric Chirped-pulse Amplification
- 2021
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In: 2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2021. - : IEEE Lasers and Electro-Optics Society. - 9781665418768
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Conference paper (peer-reviewed)abstract
- Optical parametric chirped-pulse amplification (OPCPA) [1] is an established light amplification technique with many beneficial properties, like high single pass gain, scalability, large spectral bandwidth, tunability and good conversion efficiency. Different methods have been proposed for optimization of conversion [2] - [4] mainly altering the pump or the crystal properties. However, seed manipulation to increase the OPCPA conversion efficiency has been only described in a general spatiotemporal field optimization theory so far [5]. Here, we show numerical and experimental results of a novel method to improve the gain saturation in an ultra-broadband OPCPA, hence conversion efficiency, by applying an adaptive spectral filter function to the seed pulses.
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- Fischer, Peter, et al.
(author)
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Saturation control of an optical parametric chirped-pulse amplifier
- 2021
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In: Optics Express. - 1094-4087. ; 29, s. 4210-4218
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Journal article (peer-reviewed)abstract
- Optical parametric chirped-pulse amplification (OPCPA) is a light amplification technique that provides the combination of broad spectral gain bandwidth and large energy, directly supporting few-cycle pulses with multi-terawatt (TW) peak powers. Saturation in an OPCPA increases the stability and conversion efficiency of the system. However, distinct spectral components experience different gain and do not saturate under the same conditions, which reduces performance. Here, we describe a simple and robust approach to control the saturation for all spectral components. The demonstrated optimal saturation increases the overall gain, conversion efficiency and spectral bandwidth. We experimentally obtain an improvement of the pulse energy by more than 18%. This technique is easily implemented in any existing OPCPA system with a pulse shaper to maximize its output.
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- Fischer, Peter, et al.
(author)
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Towards a 100 TW, sub-5-fs Optical Parametric Synthesizer
- 2020
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In: <em>OSA High-brightness Sources and Light-driven Interactions Congress 2020 (EUVXRAY, HILAS, MICS)</em>. - : Optical Society of America. - 9781943580736
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Conference paper (peer-reviewed)abstract
- We report on details of a peak-power upgrade of a sub-5-fs Optical Parametric Synthesizer towards 100TW. System design, pump pulse delaying and relay imaging system arepresented. A tailored second and third harmonic generation reaches conversion efficiencies of 80% and 60% with 80ps pump pulses.
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- Fitting, H.-J., et al.
(author)
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Cluster growth and luminescence in ion-implanted silica
- 2008
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In: EMC 2008 14th European Microscopy Congress 1–5 September 2008, Aachen, Germany Volume 2: Materials Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783540852254 - 9783540852261 ; , s. 17-18
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Conference paper (peer-reviewed)
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