1Journées Scientifiques de l’EDOM March 8, 2011

10 fs laser chain based on optical 10 fs laser chain based on optical parametric chirped pulse amplificationparametric chirped pulse amplification

Lourdes Patricia RamirezEquipe Lasers Solides et Applications

Laboratoire Charles Fabry de l’Institut d’Optique (LCFIO), Palaiseau, France

Frédéric DruonDirecteur de thèse

2Journées Scientifiques de l’EDOM March 8, 2011

OutlineOutline

• Motivation: Front end of the Apollon laser• Optical parametric chirped pulse amplification (OPCPA)• Seed source for OPCPA

- Ultrashort approach- Direct XPW approach

• Summary and future work

3Journées Scientifiques de l’EDOM March 8, 2011

Front end of the Apollon 10 PW laser Front end of the Apollon 10 PW laser

High contrast, CEP stable, sub-10 fs, >100 µJ, 1 kHz

Ultrashort seed source @ 800 nm

HEC-DPSSL pumpedhigh rep-rate amplifiers

(Yb:KGW, YAG, CaF2)2 J @ 1030 nm, 10-100 Hz

SHG: ps-ns1 J @ 515 nm

10-100 Hz

Pump source @ 515 nm

NOPCPA(BBO or LBO)

Optical synchronization

Noncollinear Optical Parametric Chirped Pulse

Amplification stages

<10 fs, 100 mJ, @800 nm, 10-100 Hz

10 TW!

Applications: high harmonic generation, attosecond physics, particle acceleration, plasma physics, high energy physics experiments

4Journées Scientifiques de l’EDOM March 8, 2011

Optical parametric amplification (OPA)Optical parametric amplification (OPA)

• Extremely broad amplification bandwidth

• High gain per single pass• High quantum efficiency• Low thermal effects• Reduced amplified

spontaneous emission – high energy and intensity contrast ratio pulses

• Scalability to high energies

Nonlinear CrystalX(2)

p s i

Nonlinear CrystalX(2)

pump

pump

signal

residual pump

amplified signal

idler

signal

idler

Generation

Amplification

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Chirped pulse amplification (CPA)Chirped pulse amplification (CPA)

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OPA + CPA = OPCPAOPA + CPA = OPCPA

Replace with nonlinear crystals e.g. BBO, LBO, KDP

7Journées Scientifiques de l’EDOM March 8, 2011

Front end of the Apollon 10 PW laser Front end of the Apollon 10 PW laser

High contrast, CEP stable, sub-10 fs, >100 µJ, 1 kHz

Ultrashort seed source @ 800 nm

HEC-DPSSL pumpedhigh rep-rate amplifiers

(Yb:KGW, YAG, CaF2)2 J @ 1030 nm, 10-100 Hz

SHG: ps-ns1 J @ 515 nm

10-100 Hz

Pump source @ 515 nm

NOPCPA(BBO or LBO)

Optical synchronization

Noncollinear Optical Parametric Chirped Pulse

Amplification stages

<10 fs, 100 mJ, @800 nm, 10-100 Hz

10 TW!

8Journées Scientifiques de l’EDOM March 8, 2011

Ultrashort seed sourceUltrashort seed source

• Sub-10 fs , >100 µJ, 1 kHz, CEP stable, high contrast ratio at 800 nm • 2 approaches:

Commercial ultrashort Ti:Sa system25 fs, 1.5 mJ, 1 kHz, CEP stable, CR ~ 108

Ultrashort approach: 5 fsHollow core fiber (HCF) pulse compression

Cross polarized wave generation (XPW)5 fs, 100 µJ, CEP preserving, CR ~ 1010

Main disadvantages: low efficiency- Compression in between two stages

Direct XPW: Sub-10 fs approachSpectral broadening and contrast enhancement

via cross polarized wave generation only< 10 fs, 200-300 µJ, CEP preserving, CR ~ 1010

Advantages: higher efficiency- Single stage for broadening and contrast

enhancement- Simple and compact setup

9Journées Scientifiques de l’EDOM March 8, 2011

Ultrashort approach: hollow fiber compressionUltrashort approach: hollow fiber compression

Pulse compression:25 fs to 4.4 fs

Spectral broadening in the HCF:60 nm to 250 nm

500 600 700 800 900 1000

0.0

0.2

0.4

0.6

0.8

1.0

Inte

nsity

(a.

u.)

Wavelength (nm)

HCF 250µm diam, 1m long, 1.3bar Ne: ----E

in=1.3 mJ (~48nm)

----Eout

=0.8mJ (~250nm)

250 nm

>750 µJ

1.4mJ, 25fs>850 µJ

60nm

-30 -20 -10 0 10 20 30

0.0

0.2

0.4

0.6

0.8

1.0

Time (fs)

Inte

nsity

(a.

u.)

10

15

20

25

Pha

se (

rad)

Laser HCF

10Journées Scientifiques de l’EDOM March 8, 2011

Cross polarized wave generation (XPW)Cross polarized wave generation (XPW)

XPW is based on a degenerated four-wave mixing process governed by the anisotropy of the real part of a crystal’s third-order nonlinearity tensor.

Glan 1 Glan 2BaF2

χ(3)

Main features:- Contrast enhancement: depends on the polarizer exctinction ratio (105)- Temporal pulse shortening:- Spectral cleaning and broadening

3t3

3( ) ( )XPW LI t I t

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Ultrashort approach: HCF + XPWUltrashort approach: HCF + XPW

Energy/Spectrum FROG3ω/f-2f

~80 μJ, 5fs

~550μJ, 5fs

~100μJ

Spectral cleaning with XPW:250 nm to 200 nm

XPWHCF

-30 -20 -10 0 10 20 30

0.0

0.2

0.4

0.6

0.8

1.0

Time (fs)

Inte

nsity

(a.

u.)

0

10

20

30

40

50

60

Pha

se (

rad)

Main result: HCF + XPW5 fs, 100 μJ

Compression: 5 fs

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Direct XPWDirect XPW

2.5-mm BaF2

f = 1.5 m

20-cm hollow core waveguide

Polarizer

XPW

25-41 cm

Spatial profile of

XPW beam

Filtered spatial profile of laser

beam

Actual spatial profile of laser

beam

ff1.5 mJ25 fs

Spectral broadening with XPW:60 nm to 140 nm

Pulse compression with XPW:25 fs to 9.6 fs

Main result: Direct XPW

9.6 fs, 300 μJ!

300 μJ

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Summary and future workSummary and future work

• Implemented two seed sources for an OPCPA based laser chain.- Hollow core fiber compression and cross polarized wave generation: 5 fs, 100 µJ, 10-10 contrast ratio- Direct cross polarized wave generation: 9.6 fs, 300 µJ, 10-

10 contrast ratio• Improving the stability and reliability of the direct XPW seed

source• Developing a stretcher for the seed source• Perform OPCPA

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Merci pour votre attention!Merci pour votre attention!

15Journées Scientifiques de l’EDOM March 8, 2011

Ultrashort approach: contrast

HCFXPW

- Pre-pulses are removed.- Contrast ratio is estimated to be 10-10.