mit optics & quantum electronics group seeding with high harmonics franz x. kaertner department...

MIT Optics & Quantum Electronics Group

Seeding with High Harmonics

Franz X. Kaertner

Department of Electrical Engineering and Computer Science and

Research Laboratory of Electronics,Massachusetts Institute of Technology,

Cambridge, USA


Outline

I. Advantages of Seeding

II. High-Harmonic Generation

III. Optimization of High-Harmonic Generation

IV. Carrier-Envelope Phase Control

V. Conclusion


SASE propertiesSASE properties

0.2995 0.3 0.3005 0.3010

100

200

300

400

500

Wavelength (nm)

Pow

er (

kW/b

in)

0.2995 0.3 0.3005 0.3010

100

200

300

400

500

Wavelength (nm)

Pow

er (

kW/b

in)

0 10 20 30 40 500

1

2

3

4

5

6

7

8

Time (fs)

Pow

er (

GW

)

0 10 20 30 40 500

1

2

3

4

5

6

7

8

Time (fs)

Pow

er (

GW

)

0 10 20 30 40 5010

0

102

104

106

108

1010

Time (fs)

Pow

er (

W)

0 10 20 30 40 5010

0

102

104

106

108

1010

Time (fs)

Pow

er (

W)

GINGER simulation of SASE FEL at 0.3 nm.

Time profile Time profile (log plot) Spectrum

Electron beam parameters

Energy 4.0 GeV

Peak current (amp) 2000 A

RMS emittance 0.8 m

RMS energy spread .01 %

Charge 80 pC

Beam power 8.0 TW

Bunch FWHM 40 fs

Laser beam parameters

Pulse FWHM 35 fs (~ebeam length)

Saturation power ~3.0 GW

Energy 0.2 mJ

FWHM linewidth 7.0E-4

Saturation length 59 mFor simulation speed. True bunch length will be

longer.

W.S. Graves, MIT Bates Laboratory


Seeding for narrow linewidthSeeding for narrow linewidth

Output time

profile

Time profile (log plot) Spectrum

Seed laser parameters

FWHM 50 fs

Power 0.1 MW

Pulse energy

5 nJ

FEL output parameters

Saturation FWHM

30 fs


Saturation energy

0.1 mJ

FWHM linewidth

1.0E-5

Saturation length 28 m

GINGER simulation of

seeded FEL at 0.3 nm.

Same ebeam parameters as SASE

case.

0.2995 0.3 0.3005 0.3010

100

200

300

400

500

Wavelength (nm)

Pow

er (

MW

/bin

)

0.2995 0.3 0.3005 0.3010

100

200

300

400

500

Wavelength (nm)

Pow

er (

MW

/bin

)

0 10 20 30 40 500

0.5

1

1.5

2

Time (fs)

Pow

er (

GW

)

0 10 20 30 40 500

0.5

1

1.5

2

Time (fs)

Pow

er (

GW

)

0 10 20 30 40 5010

0

102

104

106

108

1010

Time (fs)

Pow

er (

W)

0 10 20 30 40 5010

0

102

104

106

108

1010

Time (fs)

Pow

er (

W)



Seeding for short pulseSeeding for short pulse

0.2995 0.3 0.3005 0.3010

200

400

600

800

1000

Wavelength (nm)

Pow

er (

kW/b

in)

0.2995 0.3 0.3005 0.3010

200

400

600

800

1000

Wavelength (nm)

Pow

er (

kW/b

in)

Output time

profile

Time profile (log

plot)

Spectrum

0 10 20 30 40 5010

0

102

104

106

108

1010

Time (fs)P

ower

(W

)0 10 20 30 40 50

100

102

104

106

108

1010

Time (fs)P

ower

(W

)

Seed laser parameters

FWHM 0.5 fs

Power 10.0 MW

Pulse energy

5 nJ

FEL output parameters

Saturation FWHM

0.75 fs


Saturation energy

1.5 J

FWHM linewidth

6.0E-4

Undulator length 20 m

GINGER simulation of

seeded FEL at 0.3 nm.

Same ebeam parameters as SASE

case.

0 10 20 30 40 500

0.5

1

1.5

2

Time (fs)

Pow

er (

GW

)

0 10 20 30 40 500

0.5

1

1.5

2

Time (fs)

Pow

er (

GW

)

24.5 25 25.5 26 26.5 270

0.5

1

1.5

2

Time (fs)

Pow

er (

GW

)

24.5 25 25.5 26 26.5 270

0.5

1

1.5

2

Time (fs)

Pow

er (

GW

)



High-Harmonic GenerationNoble Gas Jet (He, Ne, Ar, Kr)

100 J - 1 mJ

@ 800 nm

XUV @ 3 – 30 nm

= 10-8 - 10-5

Recombination

Propagation

-Wb

XUV

En

erg

y

x

b

0

Laser electric field

Ionization)(17.30 pbc UWN

Cut-off Harmonic:


Sub-fs High-Harmonic GenerationM. Hentschel, et al., Nature, 414, 509 (2001) A. Baltuska, et al., Nature, 421, 612 (2003)

Highest wavelength emitted depends on carrier-envelope phaseSingle-Attosecond pulse (650 as)-> Stable seed energy is only possible with phase controlled laser source

Time

Ele

ctr

ic F

ield

= 0

= /2


Dependence of HHG on carrier-envelope phase

• Atomic dipole moment depends on electric field

• HHG depends on carrier-envelope phase, particularly near cutoff

• Experiment: Laser intensity .7x1015 W/cm2, pulsewidth 5 fs, propagation of 2mm neon, for various carrier-envelope phases

• Clear dependence of HHG near the cutoff

harmonic on CEP

• Discussion with H. C. Kapteyn: Also 20 fs driver pulses need carrier-envelope stababilization

Ref. Brabec et al. …

A. Baltuska, et al., Nature, 421, 612 (2003)


Published Results:Early pioneers:

McPherson et al., J. Opt. Soc Am B4, 595 (1987)Ferry et al., J. Phys. B 21, 131 (1987)

New results:

Takahashi et al.: 16 mJ, 35 fs, @800nm 300 nJ @ ~30nm), Postdeadline Paper CLEO 2002

Schnürer et al.: Few-cycle pulse: 1mJ, 5 fs =10-6,1 nJ@ ~30nm Phys. Rev. Lett. 83, 722-725 (1999)

Bartels et al.: Shaped pulses: Nature 406, 164 (2000) improvement by a factor of 10 @ 30th harmonic H. C. Kapteyn =10-4 - 10-5 @ 30th harmonic

Quasi-Phase-Matching: Nature 421, 51 (2002) improvement by a factor of 7 @ 30th harmonic -> 1 0 nJ improvement by a factor of 100 @ 100th harmonic


High Harmonic Generation in Hollow FibersHigh Harmonic Generation in Hollow Fibers

Courtesy of M. Murnane and H. Kapteyn, JILA


Pulse shaping of drive laser can

enhance a single harmonic


Quasi-phase matching in

modulated hollow-core waveguide.

Optimization of HHGOptimization of HHG

How much improvement can we get with additional phase control How much improvement can we get with additional phase control for the very high harmonics in the water window < 4 nm ?for the very high harmonics in the water window < 4 nm ?


HHG spectra for 3 different

periodicities of modulated

waveguides.


•HHG has produced wavelengths

from 50 nm to few nanometers,

but power is very low for

wavelengths shorter than ~10 nm.

•Best power at 30 nm.

•Improvements likely to yield 10 nJ

at 8 nm.

•Rapidly developing technology.


Few-Cycle Pulse and HHG GenerationIn Photonic Bandgap Fiber

(Y. Fink, RLE@MIT)

(a) (b)(a) (b)

• Truly guided modes (assuming infinite coating thickness, strong differentiation between different modes, large core fibers effectively in single mode

• Modal Dispersion can be engineered for optimum pulse compression and/or phase and group velocity matching in HHG.

Temelkuran et al., Wavelength-scalable hollow optical fibers with large photonic bandgaps …, Nature, 2002. 420: p. 1885-1886.

ChalcogenideGlass

Poly-EtherSulfone(PES)


Modification of Dispersion in PBG-Fibers

1.2-

-10

0

10

20D

isp

ersi

on

D

(p

s/n

m-k

m)

Dielectric waveguide with uniform layers

Dielectric waveguidewith defect

1.4 1.6 21.8 2.21.2

-10

0

10

20

Vacuum wavelength (m)(m)

Dis

per

sio

n

D (

ps

/nm

-km

)

Dielectric waveguide with uniform layers

Dielectric waveguidewith defect

Matching of group and phase velocities is possible


Phase Controlled Laser Pulses

-1.0

-0.5

0.0

0.5

1.0

E-F

ield

, a

.u.

-40 -20 0 20 40

Time, fs

even odd

Carrier-Envelope Phase CE

Envelope

Field

Maximum field depends on CE

L. Xu, et al., Opt. Lett. 21, 2008, (1996)

Electric field of a 1.5-cycle optical pulse


Carrier-Envelope Phase and Frequency Metrology

Periodic Pulse Train with TR = 1f

T. Udem, et al., PRL 82, 3568 (1999)D. Jones, et al., Science 288, 635-639 (2000)

SHG

Frequencyfo ffo+ffo-......

...

0 fCEO

Sp

ectr

um

OpticalClocks

Provides an ultrastable modelocked pulse train!The clock of the Facility


Octave, Prismless Ti:sapphire Laser

Laser crystal:

2mm Ti:Al2O3

PUMP

OC 1

OC 2

Base Length = 30cm for 82 MHz Laser

L =

20

cm

BaF2 - wedges

1mm BaF2


DCM-Pairs Covering One Octave

1.0

0.8

0.6

0.4

0.2

0.0

Re

flect

ivity

12001000800600

Wavelength, nm

100

80

60

40

20

0

Gro

up

De

lay (fs)

Design M1 M2 Average M1,M2 Measured Pair

1.00000.99900.99800.9970

PumpWindow


Spectra from 80 MHz and 150 MHz Laser

-30

-25

-20

-15

-10

-5

0S

pect

rum

[dB

]

12001000800600

Wavelength [nm]

1.2

0.8

0.4

0.0

Spectrum

[a.u.]

150 MHz 80 MHz


Broadband, Prismless Ti:sapphire Laserand Carrier-Envelope Detection

Laser crysta l:2m m Ti:A l2O 3

P U M P

S ilve rM irro r

O C

B ase L e ng th = 30 cm

B aF 2 w e dg e s

1 m m B a F 2

20 c

m

1m m BBO

580nm

1160nm

-

PM T Po l.

F


-80

-60

-40R

F S

pe

ctru

m [

dB

]

80x106

6040200Frequency [Hz]

100 kHz RBW

10 kHz RBW

Carrier-Envelope Beat

Frequency Comb for Optical Metrology on Ultracold Hydrogen by Prof. Kleppner


5W -Verd i pum p laser

Sub-10 fs T i:Sapphireseed -osc illa to r

Pu lse se lecto r o f pu l-ses w ith equa l phase 1 -10 kHzrepetit ion ra te

Ti:S apph ire am plifier,1m J, 1-10 kH z

H ollow fibe r com presso r, 5 fs(op tional)

H igh H arm on icG ene ration in je t o rhollow o r PB G fiber

5m vaccum line

S low carrier-enve lope phase contro l loop

M icrostructure fibe rbasedca rrier-envelope phase con tro l (M en lo -System s) Fe m to p o we r-Pro

F em toM eter PC -D AC

D azz le rpulse shaper

High-Harmonic Seed Generation (CPA)

A. Baltuska, et al., Nature, 421, 611 (2003)

0.5 mJ


High-Harmonic Seed Generation (P-CPA)

Yb:YAG Amplifier1ns, 20mJ,

1-10 kHz@1064 nm

Q-switchedYb:YAG, 1ns, 1J1-10 kHz

2nd-Harmonic1ns, 10mJ,

1-10 kHz@ 532 nm

Carrier-EnvelopeStabilized Ti:Sapphire,

4 fs, 100MHz

GV-matchedP-CPA

with BBO

5fs,

5mJ

1-10 kHz

Stret-cher

Com-pressor

Phase Control


• Stable HHG needs phase controlled high energy pulses

(It has been shown to be possible)

•Optimization of HHG results already to 10-5 efficiency at 30 nm

-> 10 nJ seed energies.

• Photonic Band Gap fibers lead to novel opportunities for HHG

generation because of novel opportunities for phase and group

velocity matching

•Laser technology is rapidly developing from CPA P-CPA

Conclusions

mit optics & quantum electronics group seeding with high harmonics franz x. kaertner department...

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