Texas Center for
Novel, 1Joule Class, 2.5Hz, Broadband OPCPA Front End
for High Intensity Laser Systems
High Intensity Laser Science
Mikael Martinez*, Erhard Gaul, Joel Blakeney, Axel Jochmann, T. Borger, D. Hammond, R. Escamilla, M. Ringuette and Todd Ditmire
Department of Physics, The University of Texas at Austin USA *[email protected]
Background
&
Motivation
System
Design
&
Technical
Approach
We
report
on
a
1
J
class,
2.5
Hz
OPCPA
centered
at
1057
nm
with
greater
than
35
nm
bandwidth.
This
system
seeds
the
Texas
Petawatt
Laser,
a
200
J,
150
fs
OPCPA
,
Mixed
Nd:glass
system
currently
in
operation.
Our
system
is
composed
of
three
amplifier
stages.
Each
stage
uses
a
pair
of
walk
off
compensated
crystals
in
a
non‐collinear,
near
degenerate
configuration
with
one
degree
of
separation
between
pump
and
seed.
Optical
Chirped
Pulse
Amplification
(OPCPA)
offers
exciting
new
possibilities
for
high
intensity
lasers.
These
amplifiers
are
pumped
at
300MW/cm2
by
two
frequency
doubled
Nd:YAG
lasers
at
532
nm.
High
optical
gain
(109)
and
broadband
amplification
(>35
nm)
makes
OPCPA
a
good
candidate
for
seeding
high
intensity
petawatt
lasers.
7
X
7
mm
and
10
X
10
mm
BBO
crystals
are
used
in
Stages
I
&
II.
Stage
III
with
apertures
>
20mm,
uses
YCOB,
a
newly
developed
crystal.
Performance
Results
Stage I
Eseed=250pJ
Idler
Epump=147mJ
BBO
7x7x15 mm
8ns pump
Eamp= 500µJ
30
OPA_I Pump
X-Axis
6/20/05
25
20
Amplified Seed
15
10
-1
0
1
1.0
OPA_I Pump
Y-Axis
6/20/05
2
0.5
Photodiode Signal (V)
Fast Photodiode Trace
OPA_I Pump Pulse
0.0
0.20
-0.5
0.15
-1.0
0.10
-1.5
0.05
0.00
20
60
Time (sec)
80
100x10
5
10
15
20
25
30
-9
Stage II
Eseed=450 µJ
Idler
Epump=700 mJ
Eamp= 45mJ
BBO
10x10x15 mm
100
Stage II Stability Run
E(avg)= 45.8mJ
ΔE(rms)=8.0%
100
Shot to Shot Energy Stability
OPCPA Stage II
Eavg=45.8mJ
80
-3
x10
80
!Erms = 8.0%
60
60
40
40
20
20
0
Stage
III
Epump=3.2J
4J
Custom
Pump
Laser
6
8
EEseed=45mJ
seed=45mJ
Epump=3.2J
10
12
Idler
Eamp= .85 J
YCOB
25x30x15 mm
Stage III Stability Run
E(avg)= .85 J
ΔE(rms)=1.7%
14
3
1.0
Seed Near Field
1.0
0.9
0.9
0.8
0.8
Shot to Shot Energy Stability
OPCPA Stage III
Eavg=860mJ
0.7
0.6
0.7
Stage_III
fit_Stage_III
!Erms = 1.7%
0.5
0.6
0.5
0
1000
2000
3000
4000
Stage
I
YCOB
5000
High
fidelity
OPCPA
pump
lasers
are
critical
for
efficient
amplification.
BBO
1600
1400
1200
BBO
0.16
0.12
60
40
400 Avg = 3.34J
Std. Dev. = .047J
Stability =1.4% rms
200
20
3.1
3.2
Peak Power Stability Analysis
3 Hour run 4 shots
0.14
80
99% of Pulses
600
0
ASE
Suppression
Telescope
100
Histogram of Stability Run
10/27/05
Run Time 3 Hours
Min=3.07J, Max=3.46J
Pk-Pk Stability = +/-6%
Pk-Pk (99%) = +/-3.5%
800
Integral Results
1.5
J
Pump
Laser
4
x10
1000
200
mJ
Pump
2
Laser Shot Count
Stage
II
1.2
J
Pump
Eamp= 0.85J
0
Stage III Energy (J)
M.D. Perry, D. Pennington, B.C. Stuart, G. Tietbohl, J.A. Britten, et al,
Petawatt Laser Pulses Optics Letters Vol. 24, No. 30.
Parametric
Amplified
Spontaneous
Emission
(ASE)
is
problematic
and
mitigated
using
tight
spatial
filters
and
wedged
crystals.
0
Stage III
Stage III Energy (J)
I. Ross, P. Matousek et al., Analysis and optimization of optical chirped
pulse amplification, JOSA B 19, 2945-1956.
The
first
two
stages
are
pumped
by
a
commercial,
1.5
J,
8
ns
laser.
The
third
stage
is
pumped
by
a
custom
laser
specifically
designed
for
OPCPA.
It
delivers
a
2.5
Hz,
4
J,
4
ns
pulses
that
are
spatially
uniform
with
user
control
of
the
pulseshape.
# of Shots
This
approach
enables
Nd:glass
based
lasers
to
break
the
400
fs
barrier
and
compress
to
around
150
fs.
Seed Near Field
-3
YCOB
is
an
extremely
attractive
solution
for
high
average
power
and
large
aperture
OPCPA
.
It
offers
gain
close
to
BBO
with
the
scalability
of
KDP.
0
40
x10
OPCPA’s
broad
bandwidth
and
ability
to
spectrally
tailor
pulses
is
attractive
for
seeding
energetic,
Nd:glass
based
petawatt
lasers.
This
technique
can
pre‐compensate
for
limited
gain
bandwidth
and
gain
narrowing
which
limits
pulse
compression
in
this
architecture.
Pump Beam
Near Field
1.5
5
0-2
0.25
'Avg +/- 7.5%'
4 Shot Avg
0.10
0.08
0.06
0.04
0.02
3.3
3.4
0.00
0
3.5
-298
Input
seed
from
stretcher
-296
-294
-292
-290
-288
-286
-284
nSeconds
Laser Energy
Uniform Spatial
Pump Profile
Stable Output Energy
ΔE(rms)=1.4%
Low Peak Power Deviation
ΔPk Pwr ±7%
Using
OPCPA
for
spectral
compensation
enables
Nd:glass
based
peteawatts.
Nd:glass amplified spectrum
25
mm
X
30
mm
YCOB
developed
at
LLNL,
enables
scaling
of
OPCPA
apertures
OPCA spectrum
167 fs
Petawatt Shot
1.1 PW !
Conclusion
Z Liao, I Javonovic, C. Ebbers, Y. Fei and B. Chai; Energy and average power scalable
optical parametric chirped pulse amplification in yttrium calcium oxyborate;
Optics Letters, Vol. 31, No. 9.
200 J
We
have
demonstrated
a
spectrally
controlled,
stable,
high
energy
OPCPA
as
a
petawatt
front
end.
We
have
demonstrated
a
200
J
167
fs,
1.1
PW
laser
based
on
this
front
end.