generation and properties of hhg radiation · generation of attosecond pulses paul et al., science,...
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Generation and properties of HHG radiation
Anne L’HuillierLund University
1
TUTORIAL
Multiphoton
Plateau
Cutoff
Generation of high harmonics
Order
Inte
nsity
ArFerray, J. Phys B 1988
McPherson, JOSA B 1987
Nd-YAG 1 mm
30 ps
Ar
2
Generation of attosecond pulses
Paul et al., Science, 2001
Henstchel et al., Nature, 2001
Kienberger et al., Science, 2002
Single attosecond pulses3
Outline
1. HHG/ Atto for the beginner
2. HHG/ Atto for the more advanced
3. HHG : experiment
4. HHG : simulation
5. Properties of HH
6. HHG : application
Tunneling
Acceleration
Return and
recombination
Electron-wave
packet
Atomic
potential
Laser field
zteE
r
e
mti )cos(
420
0
22
2
Atoms in strong fields
5
Tunneling
Acceleration
Return and
recombination
Electron-wave
packet
Atomic
potential
Laser field
Atoms in strong fields
Corkum, PRL,1993
Schafer et al. PRL, 19936
Eedt
vdm
pph ImvE 2
21
Electron-wave
packet
Atomic
potential
Laser field
Atoms in strong fields
7
Not a laser
Not synchrotron
radiation / FEL
Parametric
process –
nonlinear optics
-1 0 1 2 3 4 5-1
-0.8
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-0.4
-0.2
0
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Tid
T= Laser period = 2.6 fs
T/2
Elektron-
vågpaket
Atomär
potentialLaserfält
Atoms in strong fields
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2250 2300 2350 2400 2450 2500 2550 2600 2650
0
1000
2000
3000
920 940 960 980 1000 1020 1040 1060
0
200
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600
800
900 920 940 960 980 1000 1020 1040 1060
0
50
100
150
200
Electric field in time E(t)
Time domain Frequency domain
-1 0 1 2 3 4 5-1
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Power spectrum |E()|2
2
T
2
1
From the time to the frequency domain
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-1 0 1 2 3 4 5-1
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1000
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3000
Electric field in time E(t)
Time domain
Power spectrum |E()|2
Harmonics = Interferences of attosecond pulses
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-4000 -3000 -2000 -1000 0 1000 2000 3000 4000-1
0
1
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0
1
-4000 -3000 -2000 -1000 0 1000 2000 3000 4000-1
0
1
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Attosecond pulses = Sum of phase-locked harmonics
NOT: Incoherent radiation from a collection of atoms
A nonlinear optical phenomenon
Laser-like radiation
Spatially and temporally
coherent
Macroscopic emission
12
Phase matching
condition
Outline
1. HHG/ Atto for the beginner
2. HHG/ Atto for the more advanced
3. HHG : experiment
4. HHG : simulation
5. Properties of HH
6. HHG : application
Single atom response
Atom
FieldElectrons
Cutoff
Time
En
erg
y a
t re
turn
0 3
.2U
p
Eph= Ip+Ec
Multiple pulses per half cycle
Time domain
Chirp
s
l
Attosecond time domain
Multiple pulses /half cycle
-2000 -1500 -1000 -500 0 500 1000 1500 2000-1
-0.8
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-0.4
-0.2
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0.2
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-2000-1500-1000-5000500100015002000-1
-0.8
-0.6
-0.4
-0.2
0
0.2
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Positive
chirp
Negative
chirp
Chirp
Femtosecond time domainIndividual harmonics
Negative chirp
-2000 -1500 -1000 -500 0 500 1000 1500 2000-1
-0.8
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)()()(
tIitiq
qqqetAtE
)()/arctan(1 zIbzqzqkzk qqq Phase
matchingDispersion Gouy Single atom
response
Macroscopic response
s
l s
Dispersion= Neutral atoms + free electrons
Outline
1. HHG/ Atto for the beginner
2. HHG/ Atto for the more advanced
3. HHG : experiment
4. HHG : simulation
5. Properties of HH
6. HHG : application
”Atto team”Johan MauritssonPer JohnssonMathieu GisselbrechtThomas FordellKathrin KlünderMarcus DahlströmMiguel Miranda
”Harmonic team”Rafal RakowskiPiotr RudawskiJörg SchwenkeChristoph Heyl
”Seeding team”Erik Mansten
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Group
Laser
Via
40 fs, 800 nm, 1J
To
5 fs, 800 nm, 1 mJ, CEP
stabilized
From
40 ps, 1064 nm, 50 mJ
• Inaugurated 1992
• Lund Laser Centre 1995
• European large scalefacility 1996
High-Power Laser Facility
Anders Persson
Claes-Göran
Wahlström
Sune Svanberg
500 m from
Multi
TW
laserHigh-
Intensity
laboratory
Attosecond
laboratory
1 kHz, 5 mJ,
35 fs phase-
stabilized
Intense
XUV
laboratory10 Hz, 40 TW
40 fs
Gas medium
Gas jet
Effusive
cell
Hollow
wave guide
1 kHz-
pulsed
gas cell
Order
IntensityIo
nis
atio
n e
ner
gy
, I p
Order
Intensity
Order
IntensityIo
nis
atio
n e
ner
gy
, I p
20 eV
30 eV
100 eV
Nisoli et al., 2002
Detection of High Harmonics
24
Attosecond experimental setup
Outline
1. HHG/ Atto for the beginner
2. HHG/ Atto for the more advanced
3. HHG : experiment
4. HHG : simulation
5. Properties of HH
6. HHG : application
26
),().,(4
),(2
),(
0
22
2
trrtrEer
etr
mt
tri
2
2
2
0
2
2
2
2 11
t
P
ct
E
cE
The problem
),(|.|),(),( trrtrtrd
),(),(),( trdtrNtrP
Coupled wave equations
Time-dependent Schrödinger equation
Strong Field Approximation
Coupled
problem!
Gaarde et al., 2006
27
zkiNL
q
q
qqqeP
c
q
z
AikA
2
0
222 2
Simplification of the problem
Paraxial approximation
Slowly-varying envelope approximation
Uncoupled!
Time-dependent Schrödinger equation
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19
29
25
M. B. Gaarde, K. J. Schafer,
M. Gisselbrecht, ALH
Profile at the
exit of the
medium
Temporal
profile
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Optimisation of the problem
Complete numerical optimization of
the number of photons vs:
- Confocal parameter,
- Focus position,
- IR intensity,
- Gas pressure
Outline
1. HHG/ Atto for the beginner
2. HHG/ Atto for the more advanced
3. HHG : experiment
4. HHG : simulation
5. Properties of HH
6. HHG / Atto : application
45 150 450
Photon energy (eV)
Spectral range and efficiency
Brabec and Krausz, RMP, 2000
Titanium
L-edge
> 700 eV
Seres et al., PRL 2004
XemJ
Murnane, KapteynMidorikawa, Salières
Multicolor / Low frequency
Energy per pulse and divergence
Loose focusing
Long medium
20 mJ
0.5 mrad
R. Zerne, PRL, 1997
M. Bellini, PRL, 1998
Coherence and Polarization of high harmonics
Spatial coherence: good!
Temporal coherence: limited by pulse
duration and chirp
Polarization: normally linear – can be made
circular by using two beams
Number of Photons- Stability
5%
Divergence and Pointing
4 %
Pointing
fluctuations : 3 %
Tunability of high harmonics
Increasing
the intensity
Ch. Heyl
Outline
1. HHG/ Atto for the beginner
2. HHG/ Atto for the more advanced
3. HHG : experiment
4. HHG : simulation
5. Properties of HH
6. HHG : application going on at the high-power laser facility
37
Multi
TW
laserHigh-
Intensity
laboratory
Attosecond
laboratory
1 kHz, 5 mJ,
35 fs phase-
stabilized
Intense
XUV
laboratory10 Hz, 40 TW
40 fs
High-power laser facility
Electron
accelerationHolography
with harmonicsPreparation of a
FLASH
campagn
Per Johnsson
Attosecond
pulses
on surfaces
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Coherent diffractive imaging with Harmonics
Kapteyn, Murnane
Ravasio et al., PRL, 2010
Digital In-Line Holography with Harmonics
Experimental resolution: 1 μm
Spot size ≈ 2 µmFocal length 27mm
Gas Cell
Single shot!
20 nm thin SiNmembrane
Electron BeamLithography
Digital In-Line Holography with Harmonics
Time-resolved electron microscopy
Imaging low energy
electrons => very
surface sensitive
XUV
IR
PEEM
Photoelectron emission microscopy
Spatial resolution: electron microscopy
Temporal resolution: pump/probe method
fs
as
Anders Mikkelsen41
Images
800 nm
linewidth
200 nm
linewidth
SEM image PEEM + XUV laser
PEEM + IR laser PEEM + IR + XUV
All images: 80x80mm242
43
Thank you for
your attention
and welcome
to Lund !