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- Heyl, Christoph, et al.
(författare)
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Macroscopic effects in noncollinear high-order harmonic generation.
- 2014
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Ingår i: Physical Review Letters. - 1079-7114. ; 112:14
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Tidskriftsartikel (refereegranskat)abstract
- We study two-color high-order harmonic generation using an intense driving field and its weak second harmonic, crossed under a small angle in the focus. Employing sum- and difference-frequency generation processes, such a noncollinear scheme can be used to measure and control macroscopic phase matching effects by utilizing a geometrical phase mismatch component, which depends on the noncollinear angle. We further show how spatial phase effects in the generation volume are mapped out into the far field allowing a direct analogy with temporal carrier envelope effects in attosecond pulse generation.
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- Jarnac, Amelie, et al.
(författare)
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Compression of TW class laser pulses in a planar hollow waveguide for applications in strong-field physics
- 2014
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Ingår i: European Physical Journal D. Atomic, Molecular, Optical and Plasma Physics. - : Springer Science and Business Media LLC. - 1434-6060. ; 68:12
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate pulse post-compression of a TW class chirped pulse amplification laser employing a gas-filled planar hollow waveguide. A waveguide throughput of 80% is achieved for 50 mJ input pulse energy. Good focusability is found and after compression with chirped mirrors a pulse duration of sub-15 fs is measured in the beam center. Whereas a total energy efficiency of approximate to 70% should be achievable, our post-compressor currently delivers 20 mJ output pulse energy (approximate to 40% efficiency), mostly limited by apertures of chirped mirrors and vacuum windows. The viability of the planar hollow waveguide compression scheme for applications in strong-field physics is demonstrated by generating high-order harmonics in a pulsed Ar gas cell.
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- Matyschok, Jan, et al.
(författare)
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Compact, high-repetition-rate OPCPA system for high harmonic generation
- 2014
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Ingår i: Frontiers in Ultrafast Optics : Biomedical, Scientific, and Industrial Applications XIV - Biomedical, Scientific, and Industrial Applications XIV. - : SPIE. - 9780819498854 ; 8972
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Konferensbidrag (refereegranskat)abstract
- A compact, high-repetition rate optical parametric chirped pulse amplifier system emitting CEP-stable, few-cycle pulses with 10 μJ of pulse energy is reported for the purpose of high-order harmonic generation. The system is seeded from a commercially available, CEP-stabilized Ti:sapphire oscillator, delivering an octave-spanning spectrum from 600-1200 nm. The oscillator output serves on the one hand as broadband signal for the parametric amplification process and on the other hand as narrowband seed for an Ytterbium-based fiber preamplifier with subsequent main amplifiers and frequency doubling. Broadband parametric amplification up to 17 μJ at 200 kHz repetition rate was achieved in two 5 mm BBO crystals using non-collinear phase matching in the Poynting-vector-walk-off geometry. Efficient pulse compression down to 6.3 fs is achieved with chirped mirrors leading to a peak power exceeding 800 MW. We observed after warm-up time a stability of < 0.5 % rms over 100 min. Drifts of the CE-phase in the parametric amplifier part could be compensated by a slow feedback to the set point of the oscillator phase lock. The CEP stability was measured to be better than 80 mrad over 15 min (3 ms integration time). The experimentally observed output spectra and energies could be well reproduced by simulations of the parametric amplification process based on a (2+1)-dimensional nonlinear propagation code, providing important insight for future repetition rate scaling of OPCPA systems. The system is well-suited for attosecond science experiments which benefit from the high repetition rate. First results for high-order harmonic generation in argon will be presented.
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- Miranda, Miguel, et al.
(författare)
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Spatiotemporal characterization of ultrashort laser pulses using spatially resolved Fourier transform spectrometry
- 2014
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Ingår i: Optics Letters. - 0146-9592. ; 39:17, s. 5142-5145
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Tidskriftsartikel (refereegranskat)abstract
- We present a method for characterizing ultrashort laser pulses in space and time, based on spatially resolved Fourier transform spectrometry. An unknown pulse is interfered with a delayed, spatially uniform reference on a CCD camera. The reference pulse is created by spatially filtering a portion of the unknown pulse. By scanning the delay between the two pulses, an interferogram is obtained at each pixel, allowing us to determine the spatially resolved phase difference between the unknown pulse and the reference pulse. High-resolution spatiotemporal characterization of an ultrashort pulse is demonstrated, and the sensitivity of the method to spatiotemporal coupling is shown for the case of a pulse with pulse front tilt. (C) 2014 Optical Society of America
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| 7. |
- Rudawski, Piotr
(författare)
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Second-generation High-Order Harmonic Sources — From CPA to OPCPA
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents two sources of extreme ultraviolet (XUV) radiation based on high-order harmonic generation (HHG) in gases. The sources were developed for experiments requiring high-flux harmonic beams or HHG pulses at high-repetition rate. These were used experimentally to image nano-scale objects. The high-flux HHG source was used for digital in-line holography, and the high-repetition rate source for photoemission electron microscopy. In addition, a conceptual design for a high-flux gas beamline for a large scale facility, Extreme Light Infrastructure - Attosecond Light Pulse Source, is described. The work focuses on the construction and development of the driving laser systems and the HHG sources, as well as on the optimization of their performance. The thesis describes the two lasers used to drive the HHG sources: a high-power laser system and a newly built optical parametric chirped pulse amplification (OPCPA) system. The two systems are both based on the chirped pulse amplification technique, but the amplification process is carried out in different ways. The high-power laser system is based on linear amplification in Ti:Sapphire while the OPCPA system uses nonlinear amplification via difference frequency generation. Furthermore, the use of multi-color driving fields to manipulate the generation process, both from the microscopic and the macroscopic points of view, was investigated. The combination of the fundamental field with its second harmonic in a non-collinear geometry allows us to probe and control macroscopic properties. The addition of loworder odd harmonics in a collinear geometry results in an enhancement of the single atom response.
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