| 1. |
- Kumar Maroju, Praveen, et al.
(författare)
-
Attosecond pulse shaping using a seeded free-electron laser
- 2020
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 578, s. 386-391
-
Tidskriftsartikel (refereegranskat)abstract
- Attosecond pulses are central to the investigation of valence- and core-electron dynamics on their natural timescales. The reproducible generation and characterization of attosecond waveforms has been demonstrated so far only through the process of high-order harmonic generation. Several methods for shaping attosecond waveforms have been proposed, including the use of metallic filters, multilayer mirrors and manipulation of the driving field. However, none of these approaches allows the flexible manipulation of the temporal characteristics of the attosecond waveforms, and they suffer from the low conversion efficiency of the high-order harmonic generation process. Free-electron lasers, by contrast, deliver femtosecond, extreme-ultraviolet and X-ray pulses with energies ranging from tens of microjoules to a few millijoules. Recent experiments have shown that they can generate subfemtosecond spikes, but with temporal characteristics that change shot-to-shot. Here we report reproducible generation of high-energy (microjoule level) attosecond waveforms using a seeded free-electron laser. We demonstrate amplitude and phase manipulation of the harmonic components of an attosecond pulse train in combination with an approach for its temporal reconstruction. The results presented here open the way to performing attosecond time-resolved experiments with free-electron lasers.
|
|
| 2. |
- Maroju, Praveen K., et al.
(författare)
-
A Novel Attosecond Timing Tool for Free-Electron Laser Experiment
- 2020
-
Ingår i: High Intensity Lasers and High Field Phenomena 2020. - 9781943580736
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate a novel timing tool for Free-Electron Lasers to determine the delay between an attosecond pulse train and infrared pulse with sub-optical-cycle resolu-. tion.
|
|
| 3. |
- Olofsson, A., et al.
(författare)
-
Opto-optical modulator (OOM) for extreme ultraviolet pulses
- 2020. - 7
-
Ingår i: Attosecond Physics. - : IOP Publishing. - 1742-6588. ; 1412
-
Konferensbidrag (refereegranskat)abstract
- There is a profound, almost symbiotic relation between electrons and photons. When light interacts with matter the electrons in the material will start to move and oscillate. When a charged particle, such as an electron, oscillates it will act as a dipole and emit light. We utilize this symbiotic relation and extend the control of light to the extreme ultraviolet (XUV) region using the newly developed XUV opto-optical modulator.
|
|
| 4. |
- Olofsson, A., et al.
(författare)
-
Phase reconstruction of high-order harmonics by quantum path interference
- 2020. - 7
-
Ingår i: Attosecond physics. - : IOP Publishing. - 1742-6588. ; 1412
-
Konferensbidrag (refereegranskat)abstract
- We present a method to retrieve the phase of XUV light generated through high-order harmonic generation, by observing the intensity dependence of the interference pattern in the far-field. This interference pattern arises from electron trajectories in the generation process. These trajectories spend different time in the continuum and the phase of the generated light will therefore depend differently on the instantaneous intensity of the driving field. By changing the intensity of the driving field the phase of the contributing trajectories can be extracted.
|
|
