Property variations of Laser components under vacuum …€¦ · Property variations of Laser...
Transcript of Property variations of Laser components under vacuum …€¦ · Property variations of Laser...
Property variations of Laser components under vacuum conditions
M. Jupé, T. Groß, H. Mädebach, K. Starke, D. Ristau, Laser Zentrum Hannover e.V., Hannover, Germany
Thin Film TechnologyDepartment
CharacterizationDevelopment of test procedures, service for analysis devices
Process developmentOptimization of coating processes, online-process monitoring
CoatingsProduction of optical coatings following customer specifications
Process DevelopmentThermal ProcessesE-beam and boat evaporationConsulting and Implementation for industrial productionCoatings for deep-UV and vacuum-UV applications
Ion Assisted Deposition (IAD)Characterization and optimization of ion sourcesProcess monitoring and controlling Rapid manufacturing, MIR-spectral range
Ion Beam Sputtering (IBS)Low optical losses, dense layer systemHigh power edge filters, Rugate filtersPrecision IBS coating technology
CoatingsProduction of custom-requested coatings
Spectral range 130nm to 5µmSmall batch sizes, special requirements
optical performance, low lossesdamage threshold, stabilitycomplex spectral requirements
Special substrates and materialscomplex geometrieslaser and nonlinear crystals fiber and laser diode facetsspecial coating materials
Optics CharacterizationDamage threshold ISO 11254157 nm, 193 nm780 nm (ultra-short pulses), 1064 nmsingle and multiple-pulse testing
Absorptance ISO 11551355nm, 532 nm, 1064 nm, 10.6 µm
Total scattering ISO 13696157 nm, 193 nm, 633 nm, 1064 nm
Spectrophotometry ISO 15368120 – 240 nm, 190 – 3200 nm, 2.5 – 25 µm
Precise Reflectometry ISO 13697532nm, 1064 nm, 10.6 µm
Development of standard characterization procedures (DIN, CEN und ISO)
What changes?
400 500 600 700 800 900 10000,0
0,2
0,4
0,6
0,8
1,0
trans
mis
sion
Wavelength [nm]
Start p=2 mbar p=5 *10-4 mbar p=4 *10-7 mbar
Spectral behavior
9000,0
0,2
0,4
0,6
0,8
1,0
trans
mis
sion
Wavelength [nm]
Start p=2 mbar p=5 *10-4 mbar p=4 *10-7 mbar
Damage threshold(measurement according ISO11254)
•Spectral curves of a HR1064 coated in a conventional electron beam process [(HL)19H -Ta2O5/SiO2]. Thespectrum significantly shifts to shorter wavelengthunder vacuum conditions.
•Damage threshold decreases stronglyin vacuum!!!
1 10 100 10005
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AR808/1064 -Ta2O5/SiO2
BI0705/BI0605
ener
gy d
ensi
ty [J
/cm
²]number of pulses
measurement in air 50%-LIDT 0%-LIDT
measurement in vacuum 50%-LIDT 0%-LIDT
Changing of the spectral behavior
• Method: spectral photometrical measurement
in the coating plant (BBM).
• Method: spectral photometrical measurement of thermal shift in with a special heating set-up.
Comparison of the measurements
Content of water in layer
Where is the water located in the layer?
• Focus on the physical absorption(The chemical bounding of hydroxide molecules on the silica is also possible.)
Porous microstructureIncluding of water in the structureChanging of the refractive indexAbsorption in the infraredObviously, changes of the laser light resistance
Demanded of layers with a higher density of the micro-structure
1. IBS 2. IAD
Coating processes
Halogen Lamp
Ion Source
OpticalFibre
Process ControlTrigger
IBS- Coating plant•Low loss optics (laser gyro mirror)•Crystal coatings•High power (Rugate)•Shift free, water free•But: High stress
IAD- Coating plant•Water free optics for the MIR-application•Shift free•Optionally stress free•But: Contamination??? Test of different
Ion sources (APS, Lion, Denton CC105)
Results of shift measurements
1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 0,01 0,1 1 10 100 1000
-0,025
-0,020
-0,015
-0,010
-0,005
0,000
BH0301
shift
pressure [mbar]
0 5000 10000 15000 20000 25000
-0,025
-0,020
-0,015
-0,010
-0,005
0,000
shift ∆λ/λ
time [s]
shift ∆λ/λ
1E-8
1E-7
1E-6
1E-5
1E-4
1E-3
0,01
0,1
1
10
100
1000
BH0301
pressure [mbar]
pressure [mbar]
1E-7 1E-6 1E-5 1E-4 1E-3 0,01 0,1 1 10 100 1000 10000-0,06
-0,05
-0,04
-0,03
-0,02
-0,01
0,00
Hysteresis of the AR-optics
∆λ/λ
pressure [mbar]
TiO2/SiO2 coated in the SyrusPro1100 AR1064 TiO2 ion assisted (APS) AR1064 TiO2 conventional
Vacuum shift of a HR1064 conventional
Vacuum shift of AR-coatings
SE2906_1
BC2406/BC2706
LC-115V106001
BE0301
SE2406b1
Sf0706_5
MB0105
MB2604_2
E060227
v060602
1 2 3 4 5 6 7 8 9 10 11 121E-6
1E-5
1E-4
1E-3
0,01
0,1
Vacuum shift overview
−∆λ/λ
Sample
electron beam ion assisted Ion beam sputter
•The samples have shown different behaviors during evacuation and venting.
•The vacuum shift of IBS-samples is negligible. For IAD –samples the vacuum shift depends on the Ion dose.
• Time of relaxation is in the range of 1 to 5 hours.• The relative accuracy of the measurement is 1E-3.
Thermal Shift Measurement
800 1000 1200 1400 1600 1800 2000 2200 2400 2600
0,78
0,80
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0,84
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0,96
Quarz with different content of OH
Tran
smis
sion
Wavelength[nm]
B C D E F G H I J K
20 30 40 50 60 70 80 90 100 110 120 130-2,5
-2,0
-1,5
-1,0
-0,5
0,0
höhereIonendosis
TiO2
ionengestützter Prozess,Ionenquelle CC-105
TiO2
konventioneller Prozess
∆λ/λ
[%]
T [°C]20 40 60 80 100 120 140 160
0,0000
0,0002
0,0004
0,0006
0,0008
0,0010
Thermal shift measurement of Sf0706
∆λ/λ
Temperature [°C]
B
•Thermal shift reveals the content of water. The results correspond withthe spectral measurements in the IR.
•Problem of thermal shift measurementis the annealing of the samples.
Damage of samples undervacuum conditions
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AR808/1064 -Ta2O5/SiO2
BI0705/BI0605
ener
gy d
ensi
ty [J
/cm
²]
number of pulses
measurement in air 50%-LIDT 0%-LIDT
measurement in vacuum 50%-LIDT 0%-LIDT
AR- coating manufactured inan e- -beam process
In air the LIDT is stable at 20 J/cm2. In vacuum the LIDT decreases dramatically.
AR- coating manufactured in an IBS process
The damage threshold is relatively low, but environment conditions do not have an influence on the LIDT.
1 10 100 10000
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AR355/532/1064 TiO2/SiO2
V060613_5 and 6
ener
gy d
ensi
ty [J
/cm
²]
number of pulses
Measurement in vacuum 50%-LIDT 0%-LIDT
Measurement in air 50%-LIDT 0%-LIDT
Damage Threshold in Air
1 10 100 10000
10
20
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AR355/532/1064 Nb2O3/SiO2
V060519_0
ener
gy d
ensi
ty [J
/cm
²]
number of pulses
50%-LIDT Hinfinit 51.4 ±1.4H1on1 92.0 ±1.5
0%-LIDT Hinfinit 21.8 ±2.4H1on1 52.9 ±2.5
1 10 100 10000
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IAD AR1064-Ta2O5/SiO2
Sf0106_3
ener
gy d
ensi
ty [J
/cm
²]
number of pulses
50%-LIDTHinfinit 37.0 ±1.7H1on1 60.5 ±1.8
0%-LIDTHinfinit 14.7 ±3.7H1on1 36.9 ±4.0
IBS-CoatingThe increasing LIDT can be achieved using alternative coating materials. Vacuum test are planned.
IAD:The damage threshold is in the range of e-
- beam coatings. Vacuum test are planned.
Summary
• Vacuum and thermal shift measurement have shown spectral shifts.
• Coatings of different processes were tested
• Coating properties change under vacuum conditions
1 10 100 10005
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AR808/1064 -Ta2O5/SiO2
BI0705/BI0605
ener
gy d
ensi
ty [J
/cm
²]
number of pulses
measurement in air 50%-LIDT 0%-LIDT
measurement in vacuum 50%-LIDT 0%-LIDT
SE2906_1
BC2406/BC2706
LC-115V106001
BE0301
SE2406b1
Sf0706_5
MB0105
MB2604_2
E060227
v060602
1 2 3 4 5 6 7 8 9 10 11 121E-6
1E-5
1E-4
1E-3
0,01
0,1
Vacuum shift overview
−∆λ/λ
Sample
electron beam ion assisted Ion beam sputter
Acknowledgements
• The European Space Agency (ESA) supported the work under the contract number: 19176/05/NL/AR. Special Thanks to Denny Wernham and Yngve Lien for the valuable discussions.