generation and properties of hhg radiation · generation of attosecond pulses paul et al., science,...

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

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Tid

T= Laser period = 2.6 fs

T/2

Elektron-

vågpaket

Atomär

potentialLaserfält

Atoms in strong fields

8

2250 2300 2350 2400 2450 2500 2550 2600 2650

0

1000

2000

3000

920 940 960 980 1000 1020 1040 1060

0

200

400

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

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1-1 0 1 2 3 4 5-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

-1 0 1 2 3 4 5-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Power spectrum |E()|2

2

T

2

1

From the time to the frequency domain

9

-1 0 1 2 3 4 5-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

2250 2300 2350 2400 2450 2500 2550 2600 2650

0

1000

2000

3000

Electric field in time E(t)

Time domain

Power spectrum |E()|2

Harmonics = Interferences of attosecond pulses

11

-4000 -3000 -2000 -1000 0 1000 2000 3000 4000-1

0

1

-4000 -3000 -2000 -1000 0 1000 2000 3000 4000-1

0

1

-4000 -3000 -2000 -1000 0 1000 2000 3000 4000-1

0

1

-4000 -3000 -2000 -1000 0 1000 2000 3000 40000

5

10

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

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

-2000-1500-1000-5000500100015002000-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Positive

chirp

Negative

chirp

Chirp

Femtosecond time domainIndividual harmonics

Negative chirp

-2000 -1500 -1000 -500 0 500 1000 1500 2000-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

)()()(

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

19

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

27

19

29

25

M. B. Gaarde, K. J. Schafer,

M. Gisselbrecht, ALH

Profile at the

exit of the

medium

Temporal

profile

28

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

38

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 !