Generation and Characterization of Intense Attosecond Pulses
(2020) FYSM60 20201Atomic Physics
Department of Physics
- Abstract
- Research on ultrafast dynamics in atoms and molecules requires short pulses. In order to resolve processes taking place on a femtosecond timescale sufficiently, these pulses require a duration on the attosecond time scale.
This thesis is about the generation of such attosecond pulses via high harmonic generation (HHG) in argon gas by a terawatt infrared (IR) laser source. The pulses are applied in a pump-probe principle on two different noble gases, helium and neon. Reconstruction of Attosecond Beating By Interference of Two-photon Transition (RABBIT) is performed to characterize the relative emission time delay between harmonics, and to reconstruct the temporal domain of the attosecond pulse. Methods used for analyzing and improving the... (More) - Research on ultrafast dynamics in atoms and molecules requires short pulses. In order to resolve processes taking place on a femtosecond timescale sufficiently, these pulses require a duration on the attosecond time scale.
This thesis is about the generation of such attosecond pulses via high harmonic generation (HHG) in argon gas by a terawatt infrared (IR) laser source. The pulses are applied in a pump-probe principle on two different noble gases, helium and neon. Reconstruction of Attosecond Beating By Interference of Two-photon Transition (RABBIT) is performed to characterize the relative emission time delay between harmonics, and to reconstruct the temporal domain of the attosecond pulse. Methods used for analyzing and improving the data extraction are introduced. Particularly the angle-resolved analysis gives unique insights into the ionization dynamics. (Less) - Popular Abstract
- The shortest time frame one can imagine is perhaps the blink of an eye or a flick of a finger. These events are rarely faster than 100 milliseconds. The attosecond pulses which are produced at the Intense XUV Beamline in Lund are way shorter than that. If they were lined up one after the other, one could fit a quadrillion pulses within this time. Of course, nobody is sitting there counting these pulses, but even measurement instruments have a hard time with this task. There is no sensor or electronical device which is able to detect them directly. A tough method named after a cute animal, the so-called RABBIT technique is used to obtain the information. Hereby, the fact that light behaves like a wave and interferes is used. By a lucky... (More)
- The shortest time frame one can imagine is perhaps the blink of an eye or a flick of a finger. These events are rarely faster than 100 milliseconds. The attosecond pulses which are produced at the Intense XUV Beamline in Lund are way shorter than that. If they were lined up one after the other, one could fit a quadrillion pulses within this time. Of course, nobody is sitting there counting these pulses, but even measurement instruments have a hard time with this task. There is no sensor or electronical device which is able to detect them directly. A tough method named after a cute animal, the so-called RABBIT technique is used to obtain the information. Hereby, the fact that light behaves like a wave and interferes is used. By a lucky coincidence of nature, two attosecond pulses of the same energy are always generated. Since they are created at the same time, they interfere with each other in such way that a special pattern is formed that can be reliably measured when scanning over a much larger time frame of femtoseconds (one trillion of a second).
A picture is received which shows how many photons are measured depending on the time (in femtoseconds) and electron kinetic energy, which is proportional to the wavelength of the pulses we have generated. The part of most interest is how the line structures in this picture, referred to so-called harmonics or sidebands, oscillate over time. Advanced methods are applied for analysis and improvement of the phase extraction of this oscillation. That information allows us to reconstruct the real pulse structure over time. This explains why RABBIT stands for Reconstruction of attosecond laser beating by interference of two photon transitions. Two different noble gases, helium and neon are investigated in this thesis by applying this technique.
So far, we have seen how to measure the pulses, but no explanation for the reason why there is a need for doing this has been stated. What’s special about the pulses is that they are amongst the shortest we are currently able to create and not many research facilities are doing this at the time. Whenever we venture into previously unexplored areas there are also great discoveries. The research on attosecond pulses brings us closer to the explanation on how ionization of atoms is happening since this process takes place on a very short time frame as well, the femtosecond range. Hence, the observation requires even shorter pulses than that in order to resolve what is happening. Finally, this is an approach to a better understanding of fundamental physics and the result will contribute to an improved basic theory about charge migration processes in atomic physics and chemistry. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9008794
- author
- Plach, Marius LU
- supervisor
-
- Per Johnsson LU
- organization
- alternative title
- Generering och karaktärisering av intensiva attosekundspulser
- course
- FYSM60 20201
- year
- 2020
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Attosecond physics, high-order harmonic generation, high harmonic generation, HHG, attosecond pulses, molecular dynamics, attosecond pulse generation, harmonic emission time delay, temporal reconstruction of attosecond pulses, strong field processes, Three-step model, RABBIT, Reconstruction of Attosecond Beating By Interference of Two-photon Transition, Terawatt Laser System, Intense XUV Beamline, XUV, LLC
- language
- English
- id
- 9008794
- date added to LUP
- 2020-06-09 19:23:51
- date last changed
- 2020-06-09 19:24:15
@misc{9008794,
abstract = {{Research on ultrafast dynamics in atoms and molecules requires short pulses. In order to resolve processes taking place on a femtosecond timescale sufficiently, these pulses require a duration on the attosecond time scale.
This thesis is about the generation of such attosecond pulses via high harmonic generation (HHG) in argon gas by a terawatt infrared (IR) laser source. The pulses are applied in a pump-probe principle on two different noble gases, helium and neon. Reconstruction of Attosecond Beating By Interference of Two-photon Transition (RABBIT) is performed to characterize the relative emission time delay between harmonics, and to reconstruct the temporal domain of the attosecond pulse. Methods used for analyzing and improving the data extraction are introduced. Particularly the angle-resolved analysis gives unique insights into the ionization dynamics.}},
author = {{Plach, Marius}},
language = {{eng}},
note = {{Student Paper}},
title = {{Generation and Characterization of Intense Attosecond Pulses}},
year = {{2020}},
}