High energy, high repetition rate pump laser system for OPCPAs A.-L. Calendron 1,2,3, L. E. Zapata...

High energy, high repetition rate pump laser system for OPCPAs

A.-L. Calendron1,2,3,L. E. Zapata1,4, H. Çankaya1,2, H. Lin4 and F. X. Kärtner1,2,3,4

1 Center for Free-Electron Laser Science, DESY, Hamburg, Germany2 The Hamburg Centre for Ultrafast Imaging

3 Physics Department, University of Hamburg4 Department of Electrical Engineering and Computer Science and Research Laboratory of

Electronics, MIT, Cambridge, MA, USA

26. August 2014

Why is high energy needed ?

n

E1, f1

E2, f2

E3, f3

E4, f4 E5, f5

E6, f6

E7, f7

E8, f8

Waveform Nonlinear Optics: study and control of strong-field light-matter interactions in atoms, molecules and solids on a sub-cycle time scale

multi-mJ IR pulses for phase-matched long-wavelength HHG

Parallel synthesis

-20 -15 -10 -5 0 5 10 15 20-1

0

1

ele

ctr

ic fie

ld

time (fs)

2.7 fsFWHM

Ti:Sapphire frequency syntheziser:Results

Cirmi et al., LPHYS (2014)Rossi et al., CLEO (2014)

Pump chain for OPCPA pumping

Cryo-Yb:YAGAmplifier

60 mJ0.6 nm, 0.4 ns1 kHz

Cryo-Yb:YAGamplifier

1.1 J0.7 nm, 0.8 ns1 kHz

Yb Master Osc.

1 nJ200 fs duration 42.5 MHz

Yb:KYW Regen

> 5 mJ 3 nm, 2 ns1 kHz

MLD grating

Compressor

~ 1 J10 ps,1 kHzCFBG

Stretcher

0.6 nJ 10 nm stretched (0.65 ns/nm)

MLD gratingCompressor

4.2 mJ, 700 fs,1 kHz

CEP Stable front-end

~10 nJ, 570 nm-2.5 µm,1 kHz

OPCPA+Frequency Synthesis

~ mJ, TL: <3 fs,1 kHz

Experimental setup

Eout

LD

M3 M2 M1

DC DCXTAL XTAL L L

λ/2

M7

M6

λ/4 PC TFP M5

M4

LPBS

S

Regenerative amp.

FI

Osc

Eseed

Eosc

CFBG1

FA1

CFBG2

FA2

CFBG3 CFBG4

C2

C1

C3

Stretcher

λ/2

TFPM8

FM1&2

RM

G1

G2

CompressorTo cryo-multi-

pass amp.

To Front-end

Yb:KYW – 42.5 MHz210 fs, nJ

CFBG + 2 YDGA0.6x ns/nmnm bandwidthEout = 0.6 nJ

Dual crystal Yb:KYW1 kHz

Multi-layer dielectric gratingDouble pass

Regenerative amplifier

Calendron et al., Opt. Expr. (submitted)

- Eout = 6.4 mJ @ 1 kHz, from 0.6 nJ seed

Long term stability

Caustic: M2 < 1.1

Comparison with simulations



60 mJ0.6 nm, 0.4 ns1 kHz


1.1 J0.7 nm, 0.8 ns1 kHz

Yb Master Osc.


Yb:KYW Regen


MLD grating

Compressor


Stretcher



4.2 mJ, 700 fs,1 kHz


~10 nJ, 570 nm-2.5 µm,1 kHz



Gain narrowing and compression

- Stretching ratio: 0.65 ns/nm- Compression of the 3.6 nm broad spectrum to <700 fs- Energy in the pedestals: 16%



60 mJ0.6 nm, 0.4 ns1 kHz


1.1 J0.7 nm, 0.8 ns1 kHz

Yb Master Osc.


Yb:KYW Regen


MLD grating

Compressor


Stretcher



4.2 mJ, 700 fs,1 kHz


~10 nJ, 570 nm-2.5 µm,1 kHz



White-light generation

Regen

Comp

TFPλ/2 L1 X1

X2

X3

X4

TFPλ/2 λ/2 TFP

L2L3

L5

Spect.

X5M1 M6

M2

C1

M3

C2 M4

C4

D1

M5

C3

PM

L6M7

BS

White-Light 1 OPA 1

OPA 2

White-Light 2

f-2f

L4



60 mJ0.6 nm, 0.4 ns1 kHz


1.1 J0.7 nm, 0.8 ns1 kHz

Yb Master Osc.


Yb:KYW Regen


MLD grating

Compressor


Stretcher



4.2 mJ, 700 fs,1 kHz


~10 nJ, 570 nm-2.5 µm,1 kHz



Cryogenic Yb:YAG amplifier: GainComposite disk

with fashioned edges

Control disk

Zapata et al., ASSL 2013, talk AF3A.10Zapata et al., Opt. Lett. (submitted)

Out

Spatial filter

Cryogenic CTD Heat

Laser Fluo

resc

ence

THE PREDICTED INCREASE IN

GAIN HOLD-OFF WAS REALIZED

Chirped pulse amplification

13

• 68 mJ pulse energy• Maximum intensity ~ 10 GW/cm2

• The output was stable at all rep. rates

28% slope eff.

Puls

e en

ergy

[mJ]

Absorbed energy [mJ]

Franz-Nodvik calc. verifed gain/loss measurements

Frantz-Nodvik

T = 93%G = 3.3x ~ 5.2 dB

Results with optimized seed laserLimitations in seed energy and stretching overcome now with the new seed: Eseed = 5.5 mJ and τ = 2.35 ns

With only 6 passes, >30mJ extracted from the disk, compared to 23 mJ with limited seed.

Output energy for 6 passes through the disk:

Summary

• Demonstration of a high energy pump-line for OPCPA pumping

• Yb doped laser systems => scalability to high energies– Suitable for pumping OPCPA´s up to high energies

• Outlook:– Compression of the high energy pulses– Parametric amplification of the front-end

Thank you for your attention !

Backups

Simulations: differential equations

Evolution of the population inversion:

Evolution of the pump fluence through the crystal:

Evolution of the laser fluence through the crystals:

Evolution of the laser fluence through the cavity:

With: and:

Simulations

Yb:KYW: CW characterization19.4 W

1031 nm

Cavity dumped:

Pointing stability: after compressor

Cryo Yb:YAG: Bandwidth measurements

Fluorescence bandwidth measured for different temperatures by adjusting the heat load on the cold head

Cryo Yb:YAG: Bandwidth measurements

Spectral bandwidth for different pump power:

Summary• Demonstration of a high energy pump-line for OPCPA pumping

– Stretcher:• CFBG, S-R = 0.65 ns /nm

– Regenerative amplifier:• Yb:KYW, dual crystal cavity• Emax = 6.5 mJ @ 1 kHz• τ = 700 fs after compression with MLD gratings

– Power amplifier:• Cryogenic Yb:YAG composite thin-disk• 6 passes: 30 mJ – 12 passes: 64 mJ

• Outlook:– 100 mJ after the power amplifier– Compression of the high energy pulses– Parametric amplification of the front-end

High energy, high repetition rate pump laser system for OPCPAs A.-L. Calendron 1,2,3, L. E. Zapata...

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