Transcript Contrast Enhancement and Measurement in PW Class Laser

LOA-ENSTA
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For PW class laser, a
contrast better than 1012 is
required
IASE has to be < 1010 W/cm²
The ASE intensity is enough to
generate a pre-plasma. The
main Pulse will interact with an
expanding plasma.
time
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M. Kalashnikov, Modern Problems of Laser Physics (2006)
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XPW is the non linear filter that will be used to reach the contrast
IR
I C - 1012 W/ cm2
(3)
XPW
However :
Input Energy is limited to  200 J
 = 10-30 %
Available seed energy for the second CPA is 20-70 J
For efficient Contrast Cleaning, Higher XPW energy must be obtained
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The first CPA is based on a standard system pumped at 10 Hz
Oscillator
CPA Laser system
XPW Module
CW Pump
Laser
Stretcher+
Dazzler
RGA+Mazzler
MPA
10 Hz Pump
Laser
Compressor
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1.00E+00
1.00E-01
1.00E-02
1.00E-03
1.00E-04
1.00E-06
Wavelength (nm)
1.00E-07
760
780
800
820
840
860
10
1.00E-08
8
0.9
1.00E-10
1.00E-11
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Sequoia Detection
Limit
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2
0.6
1.00E-12
-5.00E-11 -4.00E-11 -3.00E-11 -2.00E-11 -1.00E-11 -8.00E-25 1.00E-11
0
2.00E-11
-2
Time Delay (s)
-4
0.3
-6
-8
0.0
-100
-80
-60
-40
-20
0
Time (fs)
8
20
40
60
80
-10
100
Spectral Phase (Rad)
1.00E-09
Intensity (a.u.)
Inetensity
1.00E-05
Fundamental spectrum 80 nm FWHM
XPW spectrum 130 nm FWHM
XPW Spectrum is 1.6 times broader than the Fundamental input spectrum
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Up to 1.1 mJ is obtained
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The Temporal contrast
Is cleaned by 5 orders
Of magnitude
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As the contrast of 105 is not enough, the first CPA has been
modified to include a saturable aborber
CW Pump
Laser
Stretcher output
CPA + Saturable absorber
Oscillator
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1.00
1
0.1
CPA Laser system
0.75
Intensity (a.u.)
Normalized Signal
XPW Module
0.01
1E-3
amplifier output
Pre-Amp+
SA
1E-4
0.50
1E-5
1E-6
1E-7
Stretcher+
Dazzler
0.25
1E-8
10 Hz Pump
Laser
RGA+Mazzler
0.00
MPA
1E-10
1E-9
1E-11
CPA Laser system
700
720
740
760
1E-12
780
800
820
840
860
900
Wavelength (nm)
Compressor
1E-13
-400
-300
-200
-100
Time Delay (ps)
Output from the second CPA:
4 mJ/pulse at 10 Hz
50 nm bandwidth
880
12
0
100
Intensity
10-14 Contrast has been achieved
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1
0.1
0.01
1E-3
1E-4
1E-5
1E-6
1E-7
1E-8
1E-9
1E-10
1E-11
1E-12
1E-13
1E-14
1E-15
1E-16
-120
Detection limit
-100
-80
-60
-40
-20
0
20
40
60
Time Dealy (ps)
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Detection limit of a standard SEQUOIA : 1012
Goal: Increase of the dynamic range of the Sequoia
1) Decrease of minimum measurable signal by reducing the
equivalent noise power
• Hardware (Optics and Electronics)
2) Increase the input power/ intensity Handling the 2
saturation, modulating the  arm.
3) Increase the intensity on the THG crystal for weak
signals
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Variable attenuator
Delta function=frequency doubling
Signal=3
Frequency doubling
Frequency mixing
Detector
Acquisition
Variable delay line
2w=delta fonction
- Density filters have been moved from the input beam to the infrared
path in the sequoia => possible to increase the energy on the 2w arm
- How does the 2 saturation affects the measured temporal profile ?
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Two points must be verified :
- What is the value of the 2 saturation energy ?
- What is the impact onto the temporal profile ?
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0.25
0.1
S max
0.20
0.15
0.01
0.10
1E-3
0.05
1E-4
Smax /Eincident (mJ)
0
0.1
1
2
3
4
E incident (mJ)
5
0.25 mJ
0.5
1.15
3
5 mJ
1E-5
1E-6
C
F3
F6
F7
F8
F9
F10
1E-7
0.01
1E-8
1E-3
1E-9
-12
-8x10
1E-4
0.1
1
-12
-6x10
-12
-12
-4x10
-2x10
0
-12
2x10
temps (s)
E incident (mJ)
Saturation Energy1 mJ
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10 mJ
5 mJ
20 mJ
Reference profile
0.25mJ
2
Cross correlation
50 mJ
100 mJ
Pulse broadening
Starts at 20 mJ
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1
0.1
Simulation 5 mJ
0.01
1E-3
1E-4
1E-5
Mesuré 5 mJ
1E-6
Référence 0.25 mJ
1E-7
1E-8
-12
-4.0x10
-12
-3.0x10
-12
-2.0x10
-12
-1.0x10
0.0
-12
1.0x10
Simulations and measurements show that saturation of the SHG does not
affect the temporal profile for energy below 20 mJ
=> Around 2 orders of magnitude better should be possible.
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The Incoherent part is slightly driven into saturation
1.00E+01
1.00E+00
1.00E-01
Modif
1.00E-02
Saturé
1.00E-03
Reconnect here
1.00E-05
1.00E-06
1.00E-07
1.00E+01
1.00E-08
1.00E-09
1.00E+00
1.00E-10
1.00E-01
1.00E-11
1.00E-02
1.00E-12
1.00E-13
-5.00E-11
-4.00E-11
-3.00E-11
-2.00E-11
-1.00E-11
Time (s)
unsaturated
Saturated part
Intensity
Intensity
1.00E-04
M
o…
1.00E-03
1.00E-04 1.00E-11
-2.00E-25
1.00E-05
1.00E-06
-1.00E-12
-1.00E-26
1.00E-12
2.00E-12
3.00E-12
Time (s)
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Intensity
Intensity
Intensity
Normalized
Intensity Intensity
100
10
10
10
1
1
1
1
0.1
0.1
1
0.1
0.1
0.1
0.01
0.01
0.01
1E-3 0.01
1E-3
0.01
1E-3
1E-3
1E-4 1E-4
1E-4
1E-3
1E-4
1E-5
1E-5 1E-5
1E-4
1E-5
1E-6
1E-6
1E-6 1E-7
1E-6
1E-5
1E-7
1E-7 1E-8
1E-7
1E-9
1E-8
1E-6
-3
0
3
1E-8 1E-10
Time
Delay
(ps)
1E-9
-20
0
1E-7
1E-9
Time Delay (ps)
1E-10
1E-8
1E-10
1E-11
1E-11
1E-9
1E-12
1E-12
1E-10
1E-13
1E-13
1E-14
1E-11
1E-14
1E-15
1E-12
1E-15
1E-16
-80
-60
-40
-20
1E-13 -120
-120 -100
-100
-80
-60
-40
-20
-120
-100
-80
-60
-40
-20
00
0
Time
TimeDealy
Dealy(ps)
(ps)
Time Delay( ps)
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2020
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4040
40
6060
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•We have demonstrated the possibility to generate high
energy XPW radiation up to 1 mJ
•XPW is a good candidate for non linear filtering to obtain
short pulses with very High contrast (10-14)
• Measurement with 14 orders dynamic are possible but
improvements in high dynamic range tools still need to
be done
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