Laser damage resistance of optical coatings in the sub-ps regime ... · Optical Coatings for Laser...
Transcript of Laser damage resistance of optical coatings in the sub-ps regime ... · Optical Coatings for Laser...
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Lase r damage res i s tance o f op t i ca l coa t i ngs i n t he sub -ps reg ime : l im i t a t i ons
and imp rovemen t o f damage th resho ld
Laurent Gal la is*
A ix Marse i l le Univers i té , CNRS, Cent ra le Marse i l le , Ins t i tu t Fresnel UMR 7249, 13013 Marse i l le , France
* l a u r e n t . g a l l a i s @ f r e s n e l . f r w w w . f r e s n e l . f r / p e r s o / g a l l a i s
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Topics: High performances optical interference filters Innovative concepts and components
Staff : 7 permanent, 2 PhD
Equipement : 250m² clean rooms 5 different machines with in situ optical monitoring: EBD, IAD, PIAD, DIBS, PARMS Commercial and custom characterization systems
Topics: Physics of laser material interactions (fs to CW) Laser damage of optical components for high power applications Laser processing
Staff : 6 permanent, 3 post-doc, 7 PhD students
Equipment : fs & ns LIDT measurements CW laser processing Commercial and custom characterization systems
Opt ica l Coat ing group Laser Mater ia l In teract ion group
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
I n t r oduc t i on Laser damage
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
I n t r oduc t i onLaser damage
High power laser
Costly optic
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
I n t r oduc t i onLaser damage
High power laser
Damage Initiation
10μm
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
I n t r oduc t i onLaser damage
High power laser
Damage Initiation
Local reduction of damage resistance
redu
10μm
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
I n t r oduc t i onLaser damage
High power laser
Damage Initiation
Local reduction of damage resistance
redu
Damage growth
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
I n t r oduc t i onLaser damage
High power laser
Damage Initiation
Local reduction of damage resistance
redu
Damage growth
contamination inatio
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
I n t r oduc t i onLaser damage
High power laser
Damage Initiation
Local reduction of damage resistance
redu
Damage growth
contamination inatio
e
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
I n t r oduc t i onLaser damage
High power laser
Damage Initiation
Local reduction of damage resistance
redu
Damage growth
contamination inatio
e
loss of integrity of the component
of inte
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
I n t r oduc t i onLaser damage
High power laser
Damage Initiation
Local reduction of damage resistance
redu
Damage growth
contamination inatio
e
loss of integrity of the component
of inte
Beam obscuration
am
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
I n t r oduc t i onLaser damage
High power laser
Damage Initiation
Local reduction of damage resistance
redu
Damage growth
contamination inatio
e
loss of integrity of the component
of inte
Beam obscuration
am
Scattering, reduction of R&T
S
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
I n t r oduc t i onLaser damage
High power laser
Damage Initiation
Local reduction of damage resistance
redu
Damage growth
contamination inatio
e
loss of integrity of the component
of inte
Beam obscuration
am
Scattering, reduction of R&T
Losses LS
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
I n t r oduc t i onLaser damage
High power laser
Damage Initiation
Local reduction of damage resistance
redu
Damage growth
contamination inatio
e
loss of integrity of the component
of inte
Beam obscuration
am
Scattering, reduction of R&T
Losses LS
Wavefront modulations Wm
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
I n t r oduc t i onLaser damage
High power laser
Damage Initiation
Local reduction of damage resistance
redu
Damage growth
contamination inatio
e
loss of integrity of the component
of inte
Beam obscuration
am
Scattering, reduction of R&T
Losses LS
Wavefront modulations
Degradation of beam quality
Wm
Db
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
I n t r oduc t i onLaser damage
High power laser
Damage Initiation
Local reduction of damage resistance
redu
Damage growth
contamination inatio
e
loss of integrity of the component
of inte
Beam obscuration
am
Scattering, reduction of R&T
Losses LS
Wavefront modulations
Degradation of beam quality
Wm
Db
Damage propagation prop
Other costly optic
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Out l i ne
Basics of short pulse laser damage process Damage resistance of opt ical mater ia ls Defect- induced laser damage & damage growth Improvement of laser damage resistance
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Out l i ne
Basics of short pulse laser damage process Damage resistance of opt ical mater ia ls Damage in i t iat ion on defects Improvement of laser damage resistance
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Bas i cs o f sho r t pu l se l ase r damage p rocess Non- l inear ionizat ion
-4.0E-13 -2.0E-13 0.0 2.0E-13 4.0E-13
0
2E16
4E16
6E16
8E16
1E17
Inte
nsity
(W/m
²)
time (s)
1E14
1E17
1E20
1E23
1E26
1E29
Ele
ctro
n de
nsity
(m-3)
I on izat ion processes under h igh in tens i ty i l luminat ion
« f ree » e lect ron generat ion evolu t ion dur ing the pu lse
S c h e m a t i c r e p r e s en t a i o n o f Mu l t i -P h o t on I o n i za t i o n , Tu n n e l I o n i za t i o n , I m p a c t I o n i za t i o n a n d E l e c t r on i c Av a l a n c he
C a s e o f H f O 2 f i l m ( 5 . 5 e V) , a t 8 0 0 n m, 1 0 0 f s , 1 J / c m ²
Conduction band
Energy
Time
EV
Ec
Eg
PhotoionizationFree carrier-heating
Impact ionization& avalanche
MPI TI
Valence band
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Bas i cs o f sho r t pu l se l ase r damage p rocessEnergy deposi t ion in the mater ia l
-1.0E-12 -5.0E-13 0.0 5.0E-13 1.0E-120.0
2.0E16
4.0E16
6.0E16
8.0E16
1.0E17
1.2E17 Intensity: Incident Reflected Transmitted Absorbed
Inte
nsity
(W.c
m-2)
Time (s)
Absorbed fluence
The mate r ia l becomes s t rong ly absorb ing due to f ree e lec t ron response
S ign i f i can t absorp t ion o f the lase r i n tens i t y occu rs due to op t i ca l p roper t i es evo lu t i on
E v o l u t i on o f t h e r e a l a n d i m a g i n a ry p a r t o f t h e r e f r a c t i v e i n d e x a s a f u n c t i on o f f r e e e l e c t r on d e n s i t y, a s d e s c r i b e d b y D r u d e m o d e l *
I n t en s i t y a s a f u n c t i on o f t i m e i n t h e c a s e o f a Ta 2O 5 f i l m i r r a d i a t ed w i t h a 5 0 0 f s , 1 0 3 0 n m p u l s e . *
1E14 1E17 1E20 1E23
1.4
1.6
1.8
2.0
2.2
2.4 Nb2O5
SiO2
refra
ctiv
e in
dex
n
Electronic density (cm-3)
0.0
0.2
0.4
0.6
0.8
1.0
extin
ctio
n co
effic
ient
k
*L. Gallais et al., Appl. Phys. Lett. 97, 051112 (2010)
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Bas i cs o f sho r t pu l se l ase r damage p rocess
5.0 5.2 5.4 5.6 5.8 6.0 6.2 6.41
10
100
1000
10000
Abs
orbe
d en
ergy
per
mas
s un
it (J
/g)
Fluence (J/cm²)
Sc2O3 melting (Cp m)
Damage
Damage o f the mate r ia l t akes p lace when the depos i ted energy i s su f f i c ien t to cause mate r ia l mod i f i ca t i ons
Therma l o r mechan ica l p rocesses lead to ma te r ia l remova l
C a l c u l a t i on o f e n e r g y p e r u n i t o f m a s s d e p o s i t e d i n a S c 2O 3 f i l m w i t h 5 0 0 f s a t 1 0 3 0 n m *
H a f n i a f i l m s u b m i t t ed t o d i f f e ren t f l u e nc e s a t 5 0 0 f s / 1 030n m ( e a c h i m a g e i s a d i f f e ren t s i t e ) *
*D.B. Douti et al., Appl. Phys. A., to be published
Video not available in pdf version
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Bas i cs o f sho r t pu l se l ase r damage p rocessTime scales
Bas ic processes occur a t d i f ferent t imescales: – Excitation
Absorption by free electrons in the material – Initial free electrons in metals – Free electrons created by non-linear ionisation in dielectrics
– Energy transfer From electrons to lattice Heat diffusion in the material
– Response of the material Phase change Hydrodynamic motion, shock waves Thermo-mechanical stress
– Material removal Thermal or mechanical effects depending on the deposited energy, material properties and irradiation conditions
time
fs
ps
ns
μs μ
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Bas i cs o f sho r t pu l se l ase r damage p rocessMain di fferences wi th the ns regime
time
fs
ps
ns
μs μ
Laser / plasma
interaction will drive energy
deposition and
damage process
Energy deposition
and damage
processes are
separated in time
Main property: related to defects that can iniate a
plasma
Main property: related to intrinsic
properties of the material
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Bas i cs o f sho r t pu l se l ase r damage p rocessMater ia l modi f icat ions under mul t ip le pulses Incuba t ion e f fec t re la ted to the
accumu la t ion o f e lec t ron ic de fec ts
Decrease o f the lase r damage res i s tance under mu l t i p le pu lses
T h e d i f f e re n t p a t h w a y s f o r e x c i t a t i on , r e l a x a t i on a n d t r a p p in g o f e l e c t r ons , c h a r a c t e r i ze d w i t h a r a t e / l i f e t i me
S i O 2 s i n g l e l a y e r, 5 0 0 f s , 1 0 3 0 n m , m u l t i p l e s h o t s a t 1 0 H z ( F l u e n c e s e t t o 7 0 % o f t h e s i n g l e p u l s e t h r e s h o ld )
Conduction Band
Valence Band
Defect levels
30μm
Video not available in pdf version
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Bas i cs o f sho r t pu l se l ase r damage p rocess Thermal effects under mul t ip le pulses
1 10 100 1000 10000
0.25
0.50
0.75
1.00
1.25
1.50
Cal
cula
ted
LID
T (J
/cm
²)
Pulse number
Gold mirror: Silver mirror: 1kHz 4.3MHz
Sub-ps Laser i r rad ia t i on can loca l l y hea t the mate r ia l s
Hea t can accumu la te i f t he componen t does no t have t ime to coo l be tween two pu lses
F i n i t e - e l eme n t s i m u l a t i ons o f t h e t e m p era t u re r i s e o f a p r o t e c t ed g o l d m i r r o r 2μs a f t e r a 1 . 2 J f s , 8 0 0 n m , 1 0μm d i a m e t e r p u l s e *
F l u e n c e n e e d e d t o r e a c h t h e m e l t i ng p o i n t m e t a l l i c m i r r o r s a t 1 k H z a n d 4 . 3 MH z r e p e t i t i on r a t e s *
20°C
70°C
0 r (μm)
z (μm
)
65
0
-20
30 air
susbtrate
SiO2
Gold
*B. Nagy et al., Opt. Lett. 40, 2525 (2015)
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Out l i ne
Basics of short pulse laser damage process Damage resistance of opt ical mater ia ls Damage in i t iat ion on defects Improvement of laser damage resistance
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Damage res i s tance o f op t i ca l ma te r i a l s
0 2 4 6 8 10 120
1
2
3
4
5
AlF3
Al2O3
HfO2
Nb2O5
Sc2O3
SiO2
Ta2O5
TiO2
Y2O3
ZrO2
MgF2
CaF2 MgF2
CaF2LiF
Al2O3
SiO2
KBrNaCl
InfrasilBaF2
ZnSZnSe
GeSi
LIDT
(J/c
m²)
Bandgap (eV)
Ag, Pt
Thin films:
In t r insic Laser- Induced Damage Threshold
1.2 1.4 1.6 1.8 2.0 2.2 2.40
1
2
3
4
5 AlF3
Al2O3
Al2O3/AlF3
Al2O3/SiO2
HfO2
HfO2/SiO2
MgF2
Nb2O5
Nb2O5/SiO2
Sc2O3
SiO2
Ta2O5
Ta2O5/SiO2
TiO2
Y2O3
ZrO2
ZrO2/SiO2
LIDT
(J/c
m²)
Refractive index
D i rect dependence of L IDT on the mater ia l bandgap
Clear corre la t ion between the re f ract ive index and LIDT
L I D Ts o f o p t i c a l m a t e r i a l s t e s t e d i n s i n g l e - s h o t a t 5 0 0 f s a n d 1 0 3 0 n m a s a f u n c t i on o f t h e m e a s u red o p t i c a l b a n d g a ps *
L I D Ts o f o p t i c a l t h i n f i l m m a t e r i a l s a s a f u n c t i on o f r e f r a c t i v e i n d e x a t 1 0 3 0 nm * *
*L. Gallais et al., Appl. Opt. 53, A186 (2014) **B. Mangote et al., Opt. Lett. 37, 1478 (2012)
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Damage res i s tance o f op t i ca l ma te r i a l s
1E-13 1E-12 1E-11 1E-10 1E-9 1E-8
1
10
LID
T (J
/cm
²)
Pulse duration (s)
RLVIP EBD
Parametr ic dependence
1 2 3 40.0
0.5
1.0
1.5
2.0
LIDT
(J/c
m²)
Photon energy (eV)
Nb2O5 Simulation Ta2O5 Simulation HfO2 Simulation Al2O3 Simulation
L IDT decreases wi th pu lse durat ion for d ie lect r ics
L IDT decreases wi th wavelength
L I D T o f H f O 2 s i n g l e l a y e r c o a t i ngs m a d e b y R e a c t i v e L o w Vo l t a g e I o n P l a t i n g o r E l e c t r on B e a m D e p o s i t i on a s a f u n c t i on o f p u l s e d u r a t i on , t e s t ed a t 1 0 3 0 / 106 4nm *
L I D T a t 1 0 0 f s a s a f u n c t i on o f p h o t on e n e r g y f o r d i f f e ren t s i n g l e l a y e r c o a t i n gs * *
*L. Gallais et al., Appl. Opt. 50, C178 (2011) **L. Gallais et al., J. Appl. Phys. 117, 223103 (2015)
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Damage res i s tance o f op t i ca l ma te r i a l s
1 10 100 1000 10000 1000000
1
2
3
4
5
LID
T (J
/cm
²)
Number of pulses
1030nm 515nm 343nm
Mul t ip le pulses
1 10 100 1000 10000 1000000.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
LID
T (J
/cm
²)
Number of pulses
1030nm 515nm 343nm
Exc i ta t i ons o f m id -gap de fec t s ta tes a t the m ic roscop ic l eve l takes p lace under mu l t i p le i r rad ia t i ons , l ead ing to a dec rease o f L IDT w i th i nc reas ing pu lse number. Th is e f fec t i s s t rong ly dependen t on lase r i r rad ia t i on cond i t i ons and mate r ia l
E v o l u t i on o f t h e L I D T w i t h t h e n u m b e r o f p l u s e s a t 5 0 0 f s f o r S i l i c a f i l m d e p o s i t ed b y Ma g n e t r on S p u t t e r i n g *
E v o l u t i on o f t h e L I D T w i t h t h e n u m b e r o f p l u s e s a t 5 0 0 f s f o r N i o b i a f i l m d e p o s i t ed b y Ma g n e t r on S p u t t e r i n g *
*D.B. Douti et al., Opt. Eng. 53, 122509 (2014)
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Damage res i s tance o f op t i ca l ma te r i a l sEnvironnemental condi t ions
LIDT decrease wi th pressure is observed for ox ides
No dependence wi th temperature is observed for cryogenic condi t ions
L I D T o f H a f n i a a n d S c a n d i a a t 1 0 3 0 nm , 5 0 0 f s , i n a i r a n d u n d e r v a c uu m ( 1 0 - 3m b a r ) *
L I D T ( 1 0 3 0 nm , 5 0 0 f s ) o f d i e l e c t r i c s m a t e r i a l s u n d e r v a c u u m a t d i f f e re n t t e m p e ra t u res *
*A. Hervy et al., Opt. Eng., to be published
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Out l i ne
Basics of short pulse laser damage process Damage resistance of opt ical mater ia ls Damage in i t iat ion on defects Improvement of laser damage resistance
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Sub-ps damage i n i t i a t i on on de fec t sPhysical process
Localized absorption of laser radiation
Energy transfer to host material
Mechanical & Hydrodynamic effects
-Free electron absorption -Photo-ionization -Electron dynamics -Non linear absorption -E-field distribution effects
-electron/phonon relaxation thermal conduction and radiation -plasma ball formation -avalanche ionization -melting, vaporisation -laser driven absorption
-high internal pressure, -thermomechanical stress -shock wave -spalliation -fragmentation -ejection
Small precursors can initiate a cascade of events that can result in a macroscopic damage
time fs ps ns μs
Sub-ps pulse
ns pulse
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Sub-ps damage i n i t i a t i on on de fec t s Defect in i t iat ion
Macroscop ic de fec ts can induce s t rong l oca l i n tens i t y enhancement
Loca l reduc t ion o f damage th resho ld i s observed on nodu la r de fec ts
F D T D s i m u l a t i on s o f | E | ² d i s t r i bu t i ons f o r a n o d u l a r d e f e c t i n a H f O 2/ S i O 2 H R m i r r o r *
D a m a g e i n i t i a t ed b y a n o d u l a r d e f e c t s o n a H R m i r r o r u n d e r s u c c es s i v e i r r a d i a t i ons a t 1 . 4 5 J 2. *
10μm
0 1 2
5 10 50
*L. Gallais et al., Opt. Lett. 39, 1545 (2014)
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Sub-ps damage i n i t i a t i on on de fec t sDamage densi t ies
Spec i f i c damage tes t p rocedures can be app l ied to quan t i l f y l im i t i ng de fec ts (damage dens i t i es / f l uence)
I so la ted damage even ts re la ted to de fec ts can occur fo r f l uences s ign i f i can t l y l ower than the “ i n t r i ns i c ” L IDT
S c h e m a t i c d e s c r i p t i on o f a R a s t e r s c a n t e s t
D a m a g e s i t e s r e v e a l ed b y a R a s t e r s c a n t e s t o n a H R MML D m i r r o r ( 1 0 3 0nm , 1 p s )
4mm
1on1 LIDT 0.8J/cm² Raster scan
100 damages/cm² @0.4J/cm²
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Sub-ps damage i n i t i a t i on on de fec t sDamage growth
Once damage s i te i s i n i t i a ted , ca tas t roph ic damage g rowth l im i t s the op t i cs l i f e t ime
Growth can be t r i ggered fo r f l uences as low as 50% o f the in t r i ns i c damage th resho ld o f the componen t .
S e q u e nc e o f s h o t s o n a d e f e c t -i n i t i a t ed d a m a g e , a t a f l u e n c e s e t t o 6 0 % o f t h e s i n g l e p u l s e L I D T *
E v o l u t i on o f t h e p r o b a b i l i t y o f g r o w t h a s a f u n c t i o n o f f l u e n c e ( n o r ma l i ze d w i t h r e s p ec t t o t h e s i ng le p u l s e L I DT ) . HR m i r r o r, 45 ° , P, 1 0 3 0 n m, 1 p s . *
20μm
*M. Sozet et al., Opt. Lett. 41, 2342 (2016)
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O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Out l i ne
Basics of short pulse laser damage process Damage resistance of opt ical mater ia ls Damage in i t iat ion on defects Improvement of laser damage resistance?
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Imp rovemen t o f l ase r damage res i s tance
1.2 1.4 1.6 1.8 2.0 2.2 2.40
1
2
3
4
5 AlF3
Al2O3
Al2O3/AlF3
Al2O3/SiO2
HfO2
HfO2/SiO2
MgF2
Nb2O5
Nb2O5/SiO2
Sc2O3
SiO2
Ta2O5
Ta2O5/SiO2
TiO2
Y2O3
ZrO2
ZrO2/SiO2
LIDT
(J/c
m²)
Refractive index
Mater ia ls & manufactur ing
Eng ineered mate r ia l s such as b ina ry m ix tu res a re i n te res t ing comb ina t ions fo r i n te r fe rence coa t ings used in h igh -power app l i ca t ions
Reduc t ion o f de fec t dens i t i es re la ted to the manu fac tu r ing p rocess
L I D T o f I B S S c 2O 3/ S i O 2 m i x t u re s c o m p are d t o o t h e r c o a t i ng m a t e r i a l s *
R a s t e r s c a n a n d 1 o n 1 m e a s u re men t s o n d i f f e r en t H R m i r r o r s ( 1 0 5 3 n m, 67 5 f s , 45 ° AOI , P po la r ) *
*M. Mende et al., Appl. Opt. 52, 1368 (2013) *M. Sozet et al., Opt. Lett. 40, 2091 (2015)
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Imp rovemen t o f l ase r damage res i s tanceOpt imizat ion of E-f ie ld distr ibut ion
The theore t i ca l L IDT o f a componen t can be ob ta ined f rom the knowledge o f the E- f i e ld d i s t r i bu t ion and L IDT o f ma te r ia l s
S ign i f i can t improvement can be ob ta ined w i th op t im iza t ion o f the E- f i e ld d i s t r i bu t ion
O pt i m i za t i on o f 45 ° b r oadb and HR-c o a t i ng s . f o r A p p o l o n 1 0 P W l a s e r p r o j e c t *
L I D T o f b r o a d ba nd r e f l e c t i v e m i r r o r s : R > 9 9 % , > 2 5 0 nm ( S ) / 1 6 0 n m ( P ) Te s t s a t 8 0 0 n m , 4 0 f s , 5 k H z* *
LIDT
(J/c
m²)
Standard (commercial samples) ( p ) Optimized p
0
2
/4 T
iO2/
SiO
2
*A. Hervy et al., Opt. Eng., to be published **A. Hervy, PhD thesis, 2016
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Imp rovemen t o f l ase r damage res i s tance Post processing
Laser cond i t i on ing o r the rma l annea l ing can s ign i f i can t l y enhance the L IDT
Spec i f i c t rea tmen ts can m i t i ga te (a r res t ) l ase r damage g rowth
I m p r ov em en t o f L I D T o n t h e s u r f a c e o f f u s e d s i l i c a o p t i s a t 3 5 5 n m, 3 n s , w i t h i s o t h e rm a l an nea l i ng a t 105 0°C f o r 12h *
E x a m p l e o f C O 2 l a s e r p r o c e s s i ng o f d a m a g e o n f u s e d s i l i c a f o r t h e L a s e r Me g a J o u le p r o j e c t *
*T. Doualle et al., J. Appl. Phys. 119, 213106 (2016) *T. Doualle et al., Submitted
2mm
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O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Conc lus ions
The phys ics o f laser damage in the sub-p icosecond reg ime is qu i te wel l understood
In t r ins ic per formances of opt ica l mater ia ls can be ranked based on the i r bandgap and sca l ing laws can be der ived
Consequent ly theoret ica l ly h igh laser damage threshold opt ics can be des igned based on avai lab le mater ia ls
However for appl icat ions two main po in ts need to be cons idered and deeply s tud ied:
‘Incubation’, ‘fatigue’ or heat accumulation effects of the materials under multiple pulses The densities of growing damage sites related to manufacturing defects and/or contamination
Post process ing techniques that have been appl ied in the ns reg ime (anneal ing, laser condi t ion ing, damage growth mi t igat ion,etc . . ) cou ld a lso be of potent ia l in terest
O p t i c a l C o a t i n g s f o r L a s e r A p p l i c a t i o n s , B u c h s , 9 t h j u n e 2 0 1 6
Thank you fo r you r a t t en t i on !Acknowledgments
Laser Material Interactions group Optical Coating group
CESTA/Laser Damage group, PETAL project, LMJ project
Laser Research Center / Laser Damage group
Laser Components Department
Apollon project Coating department