Upload
valerie-cobb
View
215
Download
0
Tags:
Embed Size (px)
Citation preview
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
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
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
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%
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
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
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
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