| 1. |
- Brizuela, Fernando, et al.
(författare)
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Efficient high order harmonic generation boosted by below threshold harmonics
- 2013
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- High-order harmonic generation (HHG) in gases has been established as an important technique for the generation of coherent extreme ultraviolet (XUV) pulses at ultrashort time scales. Its main drawback, however, is the low conversion efficiency, setting limits for many applications, such as ultrafast coherent imaging, nonlinear processes in the XUV range, or seeded free electron lasers. Here we introduce a novel scheme based on using below-threshold harmonics, generated in a seeding cell, to boost the HHG process in a generation cell, placed further downstream in the focused laser beam. By modifying the fundamental driving field, these low-order harmonics alter the ionization step of the nonlinear HHG process. Our dual-cell scheme enhances the conversion efficiency of HHG, opening the path for the realization of robust intense attosecond XUV sources.
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| 2. |
- Matyschok, Jan, et al.
(författare)
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Temporal and spatial effects inside a compact and CEP stabilized, few-cycle OPCPA system at high repetition rates
- 2013
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Ingår i: Optics Express. - 1094-4087. ; 21:24, s. 29656-29665
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Tidskriftsartikel (refereegranskat)abstract
- We present a compact and ultra-stable few-cycle OPCPA system. In two non-collinear parametric amplification stages pulse energies up to 17 mu J at 200 kHz repetition rate are obtained. Recompression of the broadband pulses down to 6.3 fs is performed with chirped mirrors leading to peak powers above 800 MW. The parametric amplification processes were studied in detail employing (2 + 1) dimensional numerical simulations and compared to experimental observations in terms of spectral shapes, pulse energy, spatial effects as well as delay dependent nonlinear mixing products. This gives new insights into the parametric process and design guidelines for high repetition rate OPCPA systems. (C) 2013 Optical Society of America
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| 3. |
- Miranda, Miguel, et al.
(författare)
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Ultrashort laser pulse characterization from dispersion scans : A comparison with SPIDER
- 2013
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Ingår i: 2013 Conference on Lasers and Electro-Optics, CLEO 2013. - 9781557529725 - 9781557529732
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Konferensbidrag (refereegranskat)abstract
- We investigate the performance of the recently introduced 'd-scan' technique for the characterization of ultrashort laser pulses by comparing it with a well-established technique (SPIDER). Good agreement is obtained from the two different measurements.
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| 4. |
- Rudawski, Piotr, et al.
(författare)
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A high-flux high-order harmonic source.
- 2013
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 84:7
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Tidskriftsartikel (refereegranskat)abstract
- We develop and implement an experimental strategy for the generation of high-energy high-order harmonics (HHG) in gases for studies of nonlinear processes in the soft x-ray region. We generate high-order harmonics by focusing a high energy Ti:Sapphire laser into a gas cell filled with argon or neon. The energy per pulse is optimized by an automated control of the multiple parameters that influence the generation process. This optimization procedure allows us to obtain energies per pulse and harmonic order as high as 200 nJ in argon and 20 nJ in neon, with good spatial properties, using a loose focusing geometry (f#≈400) and a 20 mm long medium. We also theoretically examine the macroscopic conditions for absorption-limited conversion efficiency and optimization of the HHG pulse energy for high-energy laser systems.
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