Transcript ppt

Modeling efforts on the
Mercury Laser system
Mercury
Andy Bayramian, Camille Bibeau, Ray Beach
Prop ’92 work: Ron White
French Collaboration with MIRO:Olivier Morice,
Bruno Legarrac, Marc Nicolaizeau, Xavier Ribeyre
Comparison of important spectroscopic and thermal
properties between pertinent laser host / dopants
Reduced diode cost due to
increased energy storage time
Extraction cross section
-20
2
(10 cm )
100
Nd doped
Yb doped
C-FAP
YAG
10
S-FAP
1
0.1
0.1
Acceptable
range
YLF
Y2SiO5
(YOS)
ASE
limited
Phosphate
glass
1
SrF2
Laser
damage
limited
Yb:S-FAP has the unique property
of high cross sections and long
lifetime
allowing efficient pumping and
extraction with a minimum number
of diodes
10
Emission lifetime (ms)
The low saturation fluence in
S-FAP allows efficient
extraction below typical
material damage thresholds
UCRL-PRES-146219
Calculation of gain
Pump Equations:
 I  z, t  n  I  z, t 

 I p  f ap  f bp  n2  f ap n0 
z
c t
 n2  z , t 
I  z, t 
n  z, t 

 p  f ap  f bp  n2  f ap n0   2
t
h p
 t 
Gain/Extraction Equations:
(Franz-Nodvik)


gi   ln 1  e Fi 1 / Fsat 1  e gi 1 


Fi  Fsat ln 1  e gi e Fi 1 / Fsat  1 
g0   f ae  f be  n2  f ae n0   em
1
h e
Fsat  e
f a  f be  em
• Feathered doping to equilibrate the
gain through the amplifier head
• Symmetric pumping from left and right
sides make gain profiles symmetric
about center slab
• 77% of the diode pump light is
transferred from the diode backplanes
to the extractable area of the amplifier
• 13% of the diode pump light is
transmitted through the amplifier due to
pump saturation
UCRL-PRES-146219
Transfer efficiency of the pump delivery system
output matches optical modeling data
He gas in
Diode Array
Hollow pump light
homogenizer
Diode Array
Laser beam
Gas - cooled
slabs
Hollow pump light
concentrator
Lineouts of model gain profile for the entire amplifier head
File: head gain profile 090701.opj Date: 090701
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1
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Theory
Experiment
0.9
0.8
0.7
0.6
8.6
Small Signal Gain
Transfer Efficiency
1.0
6.9
5.2
3.4
Row Model
Column Model
1.7
0.0
-3
-2
-1
0
Distance (cm)
0.5
0
2
4
Distance (cm)
6
8
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2
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The Mercury laser system minimizes damage by arranging
the lenses, amplifiers, Pockels cell, and mirrors near relay
planes
Pockels Cell
Reverser
Front End
Amplifier 1
Relay
plane
1.5 x output
telescope lens
Relay plane
3.5 meters
Relay plane
Relay plane
Relay plane
Amplifier 2
Deformable Mirror
UCRL-PRES-146219
Advanced beam propagation modeling using MIRO
a diffraction code developed by the French
The MIRO code uses the paraxial wave
equation with full diffraction and an adaptive
mesh, which allows accurate modelling of a
beam through an image relayed system
MIRO results include:
•F(x,y,z,t)
•I(x,y,z,t)
•Pulse shaping
•B-integral
UCRL-PRES-146219
Current Mercury models show promising results
• Ein = 20 mJ, Eout = 83 J
• Energy through
a 5X DL spot: 96.0%
a 1X DL spot: 81.2%
• B-integral (5 ns): 0.7 radians
• Using D = 300 GHz bandwidth
requires increase injection:
Ein = 165 mJ, Eout = 85.0 J
Caveats to current modeling results
•Amplifier phase files are simulations
•Low frequency information lost due to small files
•Arbitrarily randomized to simulate multiple slabs
•Phase distortions on amplifiers only
•Thermal distortions not included yet
•Benchmarking in progress UCRL-PRES-146219
against Prop 92 and experiments
B-Integral causes beam breakup as the pulswidth
decreases below 1 ns
5 ns
1 ns
UCRL-PRES-146219
0.5 ns
OPTICAD:
•architecture
•delivery efficiency
•multiplexing angle
VB 1D Pump:
•1-way 1D abs/slab
•1-way 1D gain/slab
VB 1D Extract:
•2-way 1D gain/slab
•E, B-integral, , h
•ASE, power density
OPTICAD:
1-way 2D pump light
deposition/slab
ZEEMAX/CODE V:
•Lense shape
•AAA drawings
•Expected wf error
•ghost analysis
FIDAP:
•Diffuser design
TEXTAN:
•Heat xfer coef.
Fritz VB process:
•2-way 2D gain/slab
•2D norm. source desc.
TOPAZ:
•2D temp. distribution
NIKE:
•2D map of stress
and displacement
OPL:
•2D thermal OPL map
ASAP:
•Pinhole sizes
•Pencil beam analysis
ASE:
•Slab aperture limitations
and geometry
•Edge cladding
MIRO
OPL PLOT:
•2D thermal phase map
Experimental:
Wavefront, input,
and loss
measurements
code flow chart.ppt
Prop ’92 benchmarking of the MIRO code
Front end for first 4 propagations
Energy = 0.1 J
Wavelength = 1047 nm
Temporal FWHM = 5 ns
Time exponent = 50
Height FWHM = 2.8 cm
Width FWHM = 4.8 cm
Spatial exponent in X & Y = 20
L5b
L5a
Front
End
S1-S7
FS1
L5c
L5d
FS2
PC
Output
Relay Plane
G = 2 uniform flattop
Fsat = 3.0 J/cm2
Per slab
• Currently benchmarking simple propagation such that Energy,
intensity, phase, and B-integral match
• Phase and gain files then added and re-verified
• Optional: The full mercury system modeled
UCRL-PRES-146219
M5
Trivalent ytterbium shows high cross sections and
long lifetime in the Sr5(PO4)3F (S-FAP) host
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9
9
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8
Absorption
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2
7
Emission
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4
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3
2
2
1
1
0
900
950
1000
1050
1100
1150
Wavelength (nm)
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1200
2
5
cm )
5
-20
abs ( x 10
-20
6
F5/2
900 nm
Absorption
Peak
em ( x 10
cm )
em = 6 x 10-20 cm2
abs = 9 x 10-20 cm2
em = 1.14 ms
2
F7/2
1047 nm
Emission
Peak