Strong-Field Atomic Physics

1
Strong-Field Atomic Physics
or high-order harmonics
Atoms
Laser
ions or electrons
Infrared wavelength Short pulse duration High
intensity Linear-polarized
2
Strong-Field Atomic Physics
I
The electron can tunnel through the distorted
Coulomb barrier
3
Interaction with the core
III
III
The electron wave packet interacts with the
remaining core

• Rescattered electrons
• Multiple ionization
• High-order harmonic generation

The electron is accelerated by the field, and may
return to the atomic core
II
4
Electromagnetic field
Electron trajectories
Time
Time
5
High kinetic energy electrons Above-Threshold-Ion
ization
Electron energy
IP
6
Multi-electron emission Non-sequential Ionization
780 nm 100 fs
He
Ion signal
Sequential
He
Non-sequential
He
Laser intensity
7
High-Order Harmonic Generation in Gases
Plateau
Cut-off
. .
The electron recombines with the atom, emitting
its energy as an XUV photon
III
8
High-Order Harmonic Generation in Gases
Atomic Medium
Laser
Gas cell with rare gas
Titanium-Sapphire, 800 nm 1 kHz, 2 mJ, 35 fs
pulses
9
Tunneling Acceleration in the continuum Recombinat
ion Attosecond pulse train
Time
10
Attosecond pulse train
Harmonic spectrum
Energy
Time
Is this always true?
11
Characterization of attosecond pulses in a
train RABITT technique
Photoelectron spectrum
Ip
The sideband signal depends on
12
Generation of short light pulses