Extreme Light Infrastructure Workshop – Bucharest - September, 17, 2008

Cosmin Blaga

The Dawn of Attophysics

- First Steps Towards A Tabletop Attosecond X-Ray Source -

Motivation

Single Attosecond X-Ray Pulse

Structure

< 1 nmfew keVphotons

( 1 nm ~ 1.2 keV)

Motivation

Single Attosecond X-Ray Pulse

Structure

< 1 nmfew keVphotons

( 1 nm ~ 1.2 keV)

Dynamics

1 atomic unit of time is 25 as

hugebandwidth

( 100 eV for 25 as)

Attosecond approaches

Single Attosecond X-Ray Pulse

•coherent or cascade stimulated Raman scattering

Kaplan, Harris, Sokolov….

•solid target interactions, non-relativistic and relativistic

Kaplan, Mourou, Naumova….

•4th generation light sources: XFELs

LCLS

•high harmonic generation from gasesFarkas, Toth, L’Huillier….

A quick HHG overview – The Three Step Model

IIThe free electron is acceleratedby the field, and may return to theatomic core

IIIThe electron recombines with the atom, emitting its energy as a photon

The electron tunnels through thedistorted Coulomb barrierI

e- in Coulomb + laser fields

Short trajectories

Longtrajectories

A quick HHG overview – Ponderomotive Forces

ponderomotive potential is everything at long wavelengths

•electron ponderomotive energy (au):Up = I/42

•displacement: = E/42

•PW/cm2 titanium sapphire laser:Up ~ 60 eV & ~ 50 au

A quick HHG overview

• intense laser-atom interaction produces a comb of odd harmonic• harmonics result from the physics of a field-driven electron

25 30 35 40 45

104

105

106

Sp

ectr

al D

ensi

ty

Wavelength (nm)

H17

H35

0.8 m2 x 1014 W/cm2

Argon

• macroscopic physics (phase-matching) is important

Harmonic cutoff: 3.2*UP + IP

A quick HHG overview

25 30 35 40 45

104

105

106

Sp

ectr

al D

ensi

ty

Wavelength (nm)

H17

H35

0.8 m2 x 1014 W/cm2

Argon

Center wavelength: 35 nm

FWHM bandwidth: 7 eV

TF limit LundMilano

Bordeaux

100 as 170 as 170 as

TF limit LundMilano

Bordeaux

100 as 170 as 170 as

Generating attoseconds – Lund Group’s Recipe

• intrinsic time-structure is dominated by the beating between the strong low-order harmonics

• select the plateau region by spectral filtering

temporal profile

short

long

harmonic spectrum

Generating attoseconds – Lund Group’s Recipe

Bellini et al. PRL (1998)

select the short trajectory by

spatial filtering

harmonic spectrum temporal profile

short

long

contributions from 2 dominant trajectories

Generating attoseconds – Lund Group’s Recipe

the first trajectory exhibits an intrinsic positive chirp

compress by dispersive filtering

Lund group PRL 94, 033001 (2005)

170 as

harmonic spectrum temporal profile

The case for wavelength scaling – an IR promise

Maximum classical harmonic energy: 3.2Up Ip , UP ~ I*λ2

The case for wavelength scaling – an IR promise

Maximum classical harmonic energy: 3.2Up Ip , UP ~ I*λ2

clampedat Isat

The case for wavelength scaling – an IR promise

Maximum classical harmonic energy: 3.2Up Ip , UP ~ I*λ2

clampedat Isat

nolimitation

The case for wavelength scaling – an IR promise

Maximum classical harmonic energy: 3.2Up Ip , UP ~ I*λ2

Atom Ar He Xe Ar He He

λnm

800 800 2000 2000 2000 3600

Max UP

eV

12 60 30 75 372 1200

HHG Cutoff

eV(nm)

55(22)

216(6)

108(11.5)

255(5)

1200(1)

3800(0.3)

clampedat Isat

nolimitation

The case for wavelength scaling – an IR promise

Maximum classical harmonic energy: 3.2Up Ip , UP ~ I*λ2

Atom Ar He Xe Ar He He

λnm

800 800 2000 2000 2000 3600

Max UP

eV

12 60 30 75 372 1200

HHG Cutoff

eV(nm)

55(22)

216(6)

108(11.5)

255(5)

1200(1)

3800(0.3)

clampedat Isat

nolimitation

The case for wavelength scaling – an IR promise

Maximum classical harmonic energy: 3.2Up Ip , UP ~ I*λ2

Atom Ar He Xe Ar He He

λnm

800 800 2000 2000 2000 3600

Max UP

eV

12 60 30 75 372 1200

HHG Cutoff

eV(nm)

55(22)

216(6)

108(11.5)

255(5)

1200(1)

3800(0.3)

clampedat Isat

nolimitation

First results at 2000 nm in Argon

The “toy”:

signalidler

0.5 mJ, 50 fs, 2000 nm, CEP stabilized

First results at 2000 nm in Argon

30 40 50 60 700

1

har

mon

ic y

ield

(au

)

Al

filte

r tr

ansm

issi

on

energy (eV)120 140 160 180 200 220

0

1

energy (eV)

Al a

nd Z

r fil

ter

tran

smis

sion

HHG Spectrum:

- cutoff corresponds ~351th-order harmonic- for constant conditions and bandwidth; (35-50 eV), I2 I0.8/1000- varying density alone; I2 I0.8/20

Helium Photoelectron Spectrum at 2000 nm

OPCPA for Helium HHG at 2000 nm

10Hz SECTION

STRETCHER

1kHz SECTION

Nd:YAG Diode Pumped Power Amplifier

TIME-BANDWIDTH

80MHz130ps

6nJ1064nm

1kHz130ps

1mJ 1064nm

FFS-TOPTICA

80MHz120fs

3nJ 1550nm

80MHz40fs

80pJ 2000nm

Nd:YAGOscillat

PD

STRETCHER COMPRESSOR

1kHz50fs

4mJ 2000nm

10Hz2ns

2J1064nm

80MHz100ps50pJ

2000nm

PD

FIBERLASER“FFS”

VDCCGFCC

Nd:YAGRegen

Amplifier“JAGUAR”

FR QR

BEAMshapingmodule

Nd:YAGCW-pump

HEAD

Nd:YAGCW-pump

HEAD

BD20mJ

1064nm

BD

BBO BBO

2.2 deg

Type I

BBO

2.2 degType I

BBO

Clock Synchronizer“CLX-1100”

VACUUM COMPRESSOR

10Hz100ps6mJ 2000nm

1kHz100ps6mJ 2000nm10Hz

Pulsepicker

10Hz0.5ns0.5J2000nm

10Hz60fs

0.3J2000nm

Low rep. rateNd:YAG Q-switched Laser

With Flash-Lamp Pump

2.2 degType I2.2 deg

Type I

10Hz500ps

NEAR-IR opt. pulseNd:YAG opt. pulseElectronic sync. p.

The DiMauro - Agostini Group

post-docsGilles DoumyFabrice CatoireIlya LachkoAnthony DiChiara

graduate studentsPhil Colosimo (2007)Anne Marie March Cosmin Blaga Jonathan WheelerRazvan ChirlaEmily SistrunkChristoph Roedig

collaborators: H. Muller, T. Auguste, P. Salieres, G. Paulus, K. Kulander, C. Hauri