排序方式: 共有11条查询结果,搜索用时 15 毫秒
1.
Knippels G.M.H. van der Meer A.F.G. Oepts D. van Amersfoort P.W. 《Quantum Electronics, IEEE Journal of》1997,33(1):10-17
We have investigated the optical output of the free-electron laser for infrared experiments (FELIX) when it is driven by an electron beam with a ramped energy. We show that the applied slow ramp on the electron beam energy leads to a frequency chirp on each picosecond optical pulse. Typical values for the chirp are 0.2% frequency sweep across a 1.5-ps-long optical pulse. The optical pulses were analyzed with a double-grating pair and with a second-order autocorrelator. The pulse duration was reduced in the double-grating pair by 20%. A linear dependence of the chirp on the cavity desynchronization was measured 相似文献
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Weits H.H. Knippels G.M.H. van Werkhoven G.H.C. Oepts D. van Amersfoort P.W. 《Quantum Electronics, IEEE Journal of》1997,33(3):314-323
In the strong-slippage regime of a free-electron laser, the optical pulse inside the resonator is composed of a series of subsequently growing and decaying subpulses due to a limit-cycle oscillation. The picosecond time structure of the outcoupled pulses can be quite different from that of the intracavity pulse, in case of outcoupling through a hole and for specific resonator parameters. This is demonstrated by autocorrelation measurements and corroborated by simulations 相似文献
3.
Wilke I MacLeod AM Gillespie WA Berden G Knippels GM van der Meer AF 《Physical review letters》2002,88(12):124801
We report subpicosecond electro-optic measurements of the length of individual relativistic electron bunches. The longitudinal electron-bunch shape is encoded electro-optically on to the spectrum of a chirped laser pulse. The electron-bunch length is determined by analyzing individual laser-pulse spectra obtained with and without the presence of an electron bunch. Since the length of the chirped laser pulse can be easily changed, the electron bunch can be visualized on different time scales. This single-shot imaging technique is a promising method for real-time electron-bunch diagnostics. 相似文献
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Knippels G.M.H. van de Meer A.F.G. Mols R.F.X.A.M. Oepts D. van Amersfoort P.W. Jaroszynski D.A. 《Quantum Electronics, IEEE Journal of》1996,32(6):896-904
The optical output of the free-electron laser for infrared experiments (FELIX), which operates in the regime of strong slippage, consists of picosecond pulses. Depending on the amount of cavity desynchronization, the optical pulse can develop substantial structure in the form of multiple subpulses. We present second-order autocorrelation measurements of the subpulses at several far-infrared wavelengths while applying a step-taper in the undulator field. The operation with a step-tapered undulator prevents the electrons from reabsorbing the optical field energy, leading to a smooth optical pulse. For different settings of the undulator the measured pulse shape and corresponding power spectrum are discussed. It is possible without decreasing the small-signal gain to produce a smooth high-power optical pulse during the whole saturated part of the machine pulse in an FEL oscillator with a reverse-step tapered undulator 相似文献
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Yan X MacLeod AM Gillespie WA Knippels GM Oepts D van Der Meer AF Seidel W 《Physical review letters》2000,85(16):3404-3407
Time-resolved measurements of the transverse electric field associated with relativistic electron bunches are presented. Using an ultrafast electro-optic sensor close to the electron beam, the longitudinal profile of the electric field was measured with subpicosecond time resolution and without time-reversal ambiguity. Results are shown for two cases: inside the vacuum beam line in the presence of wake fields, and in air behind a beryllium window, effectively probing the near-field transition radiation. Especially in the latter case, reconstruction of the longitudinal electron bunch shape is straightforward. 相似文献
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C Kisielowski B Freitag M Bischoff H van Lin S Lazar G Knippels P Tiemeijer M van der Stam S von Harrach M Stekelenburg M Haider S Uhlemann H Müller P Hartel B Kabius D Miller I Petrov E A Olson T Donchev E A Kenik A R Lupini J Bentley S J Pennycook I M Anderson A M Minor A K Schmid T Duden V Radmilovic Q M Ramasse M Watanabe R Erni E A Stach P Denes U Dahmen 《Microscopy and microanalysis》2008,14(5):469-477
The ability of electron microscopes to analyze all the atoms in individual nanostructures is limited by lens aberrations. However, recent advances in aberration-correcting electron optics have led to greatly enhanced instrument performance and new techniques of electron microscopy. The development of an ultrastable electron microscope with aberration-correcting optics and a monochromated high-brightness source has significantly improved instrument resolution and contrast. In the present work, we report information transfer beyond 50 pm and show images of single gold atoms with a signal-to-noise ratio as large as 10. The instrument's new capabilities were exploited to detect a buried Sigma3 {112} grain boundary and observe the dynamic arrangements of single atoms and atom pairs with sub-angstrom resolution. These results mark an important step toward meeting the challenge of determining the three-dimensional atomic-scale structure of nanomaterials. 相似文献
9.
Knippels GM van de Pol MJ Pellemans HP Planken PC van der Meer AF 《Optics letters》1998,23(22):1754-1756
Subpicosecond synchronization between a mirror-dispersion-controlled 10-fs Ti:sapphire laser and the Free-Electron Laser for Infrared Experiments has been achieved. The measured intensity cross correlation between the two lasers is consistent with a jitter of only 400 fs rms. The wide and continuous tunability of the free-electron laser (FEL; 4.2-300mum) combined with ultrashort pulse duration of six optical cycles and high pulse energy of several tens of microjoules makes a series of two-color experiments possible in a previously inaccessible wavelength range. We demonstrate these capabilities by performing a two-color pump-probe experiment to study carrier cooling in GaAs. A FEL tuned from 8 to 17mum is used as the pump, and a synchronized Ti:sapphire laser pulse serves as the probe. 相似文献
10.
L. Isaenko A. Yelisseyev S. Lobanov V. Petrov F. Rotermund J. -J. Zondy G. H. M. Knippels 《Materials Science in Semiconductor Processing》2001,4(6)
Second harmonic generation for fundamental wavelengths between 2.3 and 6 μm and optical parametric generation from 5 to 12 μm in the mid-IR are demonstrated in a new nonlinear crystal, LiInS2, exhibiting no two-photon absorption near 800 nm. Photoinduced absorption in the visible to near-IR occurring at λ<450 nm excitation can be removed with illumination at λ>500 nm or minimized by annealing in In2S3 vapor. 相似文献