Mirror Coatings for Next Generation Detector Prof. Shiuh Chao - - PowerPoint PPT Presentation
Mirror Coatings for Next Generation Detector Prof. Shiuh Chao Member of LSC Institute of Photonics Technologies (IPT) National Tsing Hua University (NTHU) Hsinchu, Taiwan, R.O.C. Workshop on Gravitational Wave activities in Taiwan (GWTW)
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Member of LSC Institute of Photonics Technologies (IPT) National Tsing Hua University (NTHU) Hsinchu, Taiwan, R.O.C.
1
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Noise Spectrum
Dominant noisesources: Coating and suspension Brownian thermal noise Quantum noise– shot noise
GW150914
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics Snipview.com
index layer, and Feud silicasubstrate (34 cmin diameter 20 cm in thickness and 40 Kg )
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
http://www.reoinc.com/
Production type IBS at LMAà Two aLIGO mirrors are coated simutaneously with planetary rotation and masking to ensure the thickness uniformity (all Zernike poly terms <0.5nm was achieved for a-LIGO)
But, need to scale-up to larger area coatings for future detector.
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Fluctuation-Dissipation Theorem says: Fluctuation of a system is proportional to its dissipation
Example: Brownian motion, Johnson noise Reducing thermal noise of the mirrorsis therefore to reduce its mechanical loss, to operate at cryogenic and go for larger beam (i.e. larger mirror) . Optically, the mirror needs to have excessively low absorption and low scattering loss to avoid effects such as thermal-lensing and phase disturbance
( ): power spectral density of mirror surface fluctuation Sx ω
! χ : mechanical susceptibility (strain-stress ratio)
( ): mechanical loss angle φ ω
: temperature of the system (K) T
Thermal noise for mirror:
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Mirror Substrate
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
aLIGO
[1]
A+
[1]
Voyager
[1] CE(pess) [1]
CE
[1]
KAGRA
[2] ET-D-HF [3] ET-D-LF [3]
Arm Length [km] 4 4 4 40 40 3 10 10 Mirror Mass [kg] 40 80 160 320 320 30 200 211 Mirror materials Silica Silica Silicon Silica Silicon Sapphire fused silica silicon Mirror Temp [k] 295 295 123 295 123 20 290 10 Sus Fiber 60cm SiO2 60cm SiO2 60cm Si 1.2m SiO2 1.2m Si Sapphire fused silica silicon Fiber Type Fiber Fiber Ribbon Fiber Ribbon Fiber Fiber Fiber Input Power [w] 125 125 300 150 220 75 500 3 Arm Power [kW] 710 1150 3000 1400 2000 810 3M 18k wavelength [nm] 1064 1064 1550 1064 1550 1064 1064 1550 NN suppresion 1 1 10 10 10
5.5/6.2 5.5/6.2 6.7/7.5 12/12 14/14
9 SQZ Factor [dB] 6 8 10 10
none 16 4000 4000 4000
LIGO document LIGO-T15TBI-v1 [2]KAGRA Study report on KAGRA interferometer observation band, 8th Sep. 2009 http://gwcenter.icrr.u-tokyo.ac.jp/en/researcher/parameter [3]ET The Einstein Telescope design study (FP7-Capacities, Grant Agreement 211743) P.243 http://www.et-gw.eu/
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Cryogenic loss leak for IBS SiO2 films at different annealing temperatures.
Glasgow”, LIGO document:LIGO-G1601854 (2016)
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Cryogenic loss peak of Ta2O5 and Ta2O5-TiO2 films
I W Martin et al., “Comparison of the temperature dependence of the mechanical dissipation in thin films of Ta2O5 and Ta2O5 doped with TiO2”, Class. Quantum Grav. 26 155012 (2009)
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
10
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
11
Need to transfer the coatings to large area substrate. Currently 100-mm diameter GaAs on silica
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
12
Multi-materials QW stack : lower optical loss but higher mechanical loss materials in the front layers and higher optical loss but lower mechanical loss in the back layers Conventional Ta2O5/SiO2 QW stack has lower optical loss but higher mechanical loss than the amorphous silicon/SiO2 QW stack Jessica Steinlechner, Iain Matin, LIGO-P1500256
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
LPCVD system
a-Si n= 3.56 (λ=1550 nm) absorption range < 700 nm SiO2 n= 1.45 (λ=1550 nm) absorption range < 200 nm SiNx n= 1.77 ~ 2.28 (λ= 1550 nm) absorption range < 540 nm SiC n= 2.58 (λ=1064nm) [1] absorption range < 380 nm
(Eg=3.26 eV)[2]
[1] Singh et al. 1971 - α-SiC; n(o) 0.488-1.064 µm [2] TAKU HAMAGUCHI／ROHM Semiconductor, Santa Clara, CA.
The CVD processes for these amorphous thin film materials are well established in IC industry :
18” silicon wafer process in IC industry. Larger than LIGO mirrors.
QW high and low index films deposited alternately in two reaction compartments National Nano Device Lab (NDL) of Taiwan
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
14
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Candidate Silicon IC-Compatible CVD Thin Films for Optical Application
a-Si SiC SiNx SiO2 Refractive index @ 1550 nm 3.5[1] 3.2-2.6[11,12] 2.6-1.8[16][30] 1.45[19,20] Absorption range <700 nm[2] <380 nm [13] <510 nm[17] <200 nm[21] Young’s modulus (GPa) 100 ~ 150[3-5] 392 ~ 694[14] 85~210[16] 72~83[20,22-25] Stress# (MPa)
+600 ~ 1200 [16] +60 ~ -257[25] Loss angle at RT 3.3x10-4e beam[8] 5x10-4sputter[8] 4x10-4 IBS [31] 9x10-5IBS [10]
~3x10-4 stress relief [18] 7.5x10-5SiN0.40@107Hz 1.4x10-5 SiN0.87 @107Hz[30] 1.49x10-4 1x10-4IBS [26-28] Cryogenic loss peak Depends on H+- concentration and heat treatment[8-10]
concentration (Preliminary results will be
presented in poster session by
5x10-4@20K[29]
# - : compressive +: tensile 15
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Ref : Donald L. Smith, et al.“ mechanism of SiNxHy Deposition from NH3-SiH4 plasma”. J.Electrochem. Soc. 137, 614-623(1990)
With fixed N2 gas flow at 980 sccm, we used 5 recipes with different gas flow rate :
Gas flow rate SiH4/NH3(sccm) Composition thickness * (nm) Refractive index† @1550nm Young’s modulus (GPa) Stress (MPa) Uncoated cantilever frequency Coated cantilever frequency 45/15 SiN0.40 159.1±2.7 2.300±0.006 103.7±5.6 120.2±15.5 103.42 103.47 38/22 SiN0.49 179.2±1.4 2.138±0.005 107.0±10.8 143.8±13.2 107.32 107.38 25/30 SiN0.65 198.5±0.8 1.930±0.002 131.6±4.8 256.7±6.6 104.88 105.02 15/45 SiN0.79 204.4±1.5 1.816±0.001 137.7±9.7 382.2±21.3 107.37 107.53 8/48 SiN0.87 211.8±0.1 1.783±0.001 137.0±9.2 412.7±20.0 106.93 107.5
Adjusting the ratio of the gas flow rate, the composition of the SiN film can be changed
Ref : J. N. Chiang, et al “Mechanistic Considerations in the Plasma Deposition of silicon nitride film” J. Electrochem.
Fabrication of SiN film on Silicon by PECVD
16 Deposit on polished surface
SiNx
Plasma
LIGO-Gxxxxxx LVC meeting, Stanford University, Aug. 25,2014 * Means QW thcknessof 1550nm † Extinction coefficient <10-4@1550nm for all
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Process chamber1：SiNx Process chamber2： SiO2
Plasma Enhanced Chemical Vapor Deposition (PECVD) for multi-layer dielectric mirror coating Silicon substrate side view
17
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Process chamber1：SiNx Process chamber2： SiO2
Plasma Enhanced Chemical Vapor Deposition (PECVD) for multi-layer dielectric mirror coating Silicon substrate side view
18
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 100 200 300 400 500
stress (MPa) SiNx composition x
80 100 120 140 160 180 200
Young's modulus (GPa)
Silicon nitride
Stress and Young’s modulus Refractive index and extinction coefficient
19
1000 2000 3000 4000 5000 6000 7000
10-6 10-5 10-4 10-3
Coating loss * Frequency (Hz) SiO2 (n=1.45) SiN0.40 (n=2.28) SiN0.87 (n=1.78) room temperature
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
20
25 50 75 100 0.0 5.0x10
1.0x10
1.5x10
2.0x10
2.5x10
3.0x10
3.5x10
4.0x10
Bending mode: 671.1 Hz 1874.7 Hz Torsional mode: 1275.8 Hz 3872.3 Hz
Coating loss Temperature(K)
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Coating loss* Frequency (Hz) Coating Loss of SiN0.40/SiO2 QW Stacks Depositedby PECVD
) ( 3
substrate coated f f s s coating
t Y t Y φ φ φ − =
1000 2000 3000 4000 5000 6000 7000
10-5 10-4 10-3
1 pair 2 pair 3 pair 4 pair
21
SiN0.40/SiO2 QW pairs deposited by all-CVD process showed room temperature mechanical loss in 10-5at 100 Hz, lower than Ta2O5-TiO2/SiO2 in current GW detector. The coating loss of SiN0.40/SiO2 QW stack does not increase with pair number, indicating that there is no significant loss in SiN0.40/SiO2 interface.
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
22
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
23
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics [1]B. J. Frey, et al, “Temperature-dependent refractive index of silicon and germanium”, SPIE Conference Series, vol. 6273, p. 2, June 2006. [2] G. D. Cody,et al, “Disorderandthe optical-AbsorptionEdge ofHydrogenatedAmorphous Silicon” ,Vol.47 No.20PHYS REV.LETT.16 NOVEMBER (1981) [3] H.W. Pan, et al, “Stress effect on mechanical loss of SiNX and α-Si film deposited by PECVD method on silicon cantilever”, LVC meeting, Pasadena USA, , Mar.17th,2015,LIGO- G1500195, [4] R. Kuschnereit, et al, “Mechanical and elastic properties of amorphous hydrogenated silicon films studied by broadband surface acoustic wave spectroscopy” Appl. Phys. A 61,269-276 (1995) [5] R. B. Wehrspohnet al, “Relative importance of the Si–Si bond and Si–H bond for the stability of amorphous silicon thin film transistors”,J. APPLIED PHYSICS VOL 87, No11, JANUARY (2000) [6] C. K. Chung, et al “Fabricationandcharacterization of amorphous Si films byPECVD for MEMS”, J. Micromech.Microeng. 15(2005) . [7] P Danesh, et al, “Mechanical stress in thina-Si:Hfilms”, Semicond.Sci. Technol. 15(2000)971–974. [8] X. Liu et al, “low energy excitations in amorphous films ofsiliconandgermanium”, Phys. Rev. B 58, 9067(1998). [9] X. Liu, et al, “Internal friction ofamorphous and nanocrystalline silicon at lowtemperatures”,Mater. Sci. Eng. 442, 307(2006). [10]P. G. Murray, et al, “Ion-beamsputteredamorphous siliconfilms forcryogenic precisionmeasurementsystems”, Phys. Rev. D 92, 062001(2015) [11] J Cardenas,et al, “Optical nonlinearities in high-confinement siliconcarbide waveguides”, Optics Letters Vol.40, No.17, 2015. [12] M. A. Nigro et al. “Measurement of the IR absorption induced by visible radiation in amorphous silicon and silicon carbide thin films by an in-guide technique”, Optical Materials 30 (2008) 1240–1243 [13] J. B. CASADY, “STATUS OF SILICON CARBIDE (SIC) AS A WlDE-BANDGAP SEMICONDUCTOR FOR HIGH-TEMPERATURE APPLICATIONS: A REVIEW”, Solid-State Electronics Vol.39,No.I0, pp.1409-1422,1996 [14] L. Jiang, et al “A review of silicon carbide development in MEMS applications”, Int. J. Computational Materials Science and Surface Engineering, Vol. 2, Nos. 3/4, 2009 . [15] C. K. Chung et al, “Global and local residual stress in silicon carbide films produced by plasma-enhanced chemical vapor deposition”, Surface & Coatings Technology 200 (2006) 4825– 4834 [16] A Stoffel, et al, “LPCVDagainst PECVD for micromechanical applications”, J. Micromech.Microeng. 6 (1996)1–13. [17] S. V. Deshpande, et al, “ Opticalproperties of silicon nltride films depositedby hot filamentchemical vapordeposition”, J, Appl. Phys. 77(12), 15June (1995) [18] D. R. Southworth , et al. “Stress and SiliconNitride A Crackin theUniversal DissipationofGlasses”, PhysRevLett.102.225503(2009) [19] V.B. Braginsky, et al, “Thermodynamical fluctuations inoptical mirror coatings”, Physics Letters A 312(2003)244–255 [20]H.W. Pan, et al, “Mechanical loss ofsilica filmon siliconcantilever depositedbyPECVDmethod”, LVC meeting, Pasadena, USA, Mar.17th ,2015, LIGO-G1500194 [21] Y. N. Xu, et al, “Electronic structure and optical properties of a and P phases of silicon nitride, silicon oxynitride, and with comparison to silicon dioxide”, PHYS. REV. B VOL 51, No. 2415JUNE (1995) . [22] J. Thum,et al, “Stress hysteresis duringthermal cyclingofplasma-enhanced chemical vapordeposited siliconoxidefilms”, J. Appli. Phys.91,2002, [23] Z. Cao , “Microbridge testingof plasma-enhancedchemical-vapor depositedsilicon oxide films onsiliconwafers”,J. Appli. Phys.97, 2005 [24] Y.G. Jung, “Evaluationofelastic modulus andhardness of thinfilms by nanoindentation”, J. Mater. Res. 19, 2004, [25] J. K. Choia ,et al, “Effects of process parameters on the growth of thick SiO2 using plasma enhanced chemical vapor deposition with hexamethyldisilazane”,Surface and Coatings Technology 1312000. [26]D. R.Crooks, et al, “Experimental measurements of mechanical dissipation associated with dielectric coatings formed using SiO2, Ta2O5 and Al2O3”Class. Quan. Grav. 23 (2006)4953-4965 [27]S. Penn, “ExploringCoatingThermal Noise via Loss in Fused SilicaCoatings”Proc.Amaldi 2009,LIGO -G0900600 [28]I. Martin, “Studies of materials for use in future interferometric gravitational wave detectors”,PhDthesis, University ofGlasgow, (2009) [29] M. Principe, “Reflective coating optimization for interferometric detectors of gravitational waves”,Vol. 23, No. 9 OPTICS EXPRESS, 4 May 2015 p.10938 [30] S. Chao, et al, “Room temperature mechanicalloss of high stress silicon nitride film measured by cantilever ring-down method on double-side coated cantilever” LVC meeting, Budapest, Hungary,Sep. 1st ,2015, LIGO-G1501068 [31] J. Steinlechner, et al, “Thermal noise reduction and absorption optimization via multimaterialcoatings”, PHYSICAL REVIEW D 91, 042001 (2015)
References for the table in page 3
24
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Thermal noise for the mirror
d ： The thickness of coating ω ： Laser beam waist σ ： The Poisson's ratio of substrate σ’ ： The Poisson's ratio of coating Y ： The Young's modulus of substrate Y’ ： The Young's modulus of coating 𝜚∥ ： Mechanical loss for the coating for strains parallel to the coating surface 𝜚⊥ ： Mechanical loss for the coating for strains perpendicular to the coating surface f ： Frequency 𝑙% ： Boltzmann constant T ： Temperature
AssumeY = Y’ , σ = σ’ and 𝜚⊥ = 𝜚∥ Assume σ = σ’=0
G M Harryet al., “Thermal noise in interferometric gravitational wave detectors due to dielectric optical coatings”, Class. Quantum Grav. 19 897–917 (2002)
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
1000 2000 3000 4000 5000 6000 7000
10-6 10-5 10-4 10-3
Coating loss * Frequency (Hz) SiO2 (n=1.45) SiN0.40 (n=2.28) SiN0.87 (n=1.78)
* First two modes are bending modes and others are torsional modes. Higher order bending modes are not shown due to high fluctuation in the clamp loss.
Coating Loss for PECVD SiO2, SiN0.40 and SiN0.87
26
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
SiN0.4/SiO2 QW Stacks
tensile stress +120MPa
SiN0.40 (n= 2.28)
compressive stress -150MPa
SiO2 (n=1.45)
1-pair SiN0.40/SiO2 QW stack
Stresses are compensated
4-pair SiN0.40/SiO2 QW stack
material* Refractive index# @1550nm Young’s modulus (GPa) Stress (MPa) Loss angle ~100Hz @ RT SiO2 1.45±0.01 83.8±1.3
(1.49±0.12) x10-4 SiN0.40 2.28±0.01 103.7±5.6 120.2±15.5 (7.49±0.72) x10-5
*All films are amorphous structure as deposited
We have deposited samples with 1, 2, 3 and 4 pairs QW stacks.
27
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Conventional dielectric multi-layer high reflector coatings
Reflectance of the mirror increases with increasing number of HL pairs Higher index contrast ---> less number of pairs ---> lower losses
Historical: Request of mirrors with very low optical loss for high precision ring-laser gyroscope and high energy lasers back in late 70’s led to invention of applying ion beam sputter to deposit laser mirror at Litton Systems (1979)
à large area coatings for mirrors of laser interference gravitational wave detector in 2000’s with low optical loss + low mechanical loss
Ion beam sputter nL：SiO2 nH：Ta2O5 with post-deposition annealing
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Ion beam sputter deposition (PVD)
(L. Pinard and LMA team, LVC meeting, Pasadena 2015)
Research IBS at NTHU Production type IBS at LMAà Two aLIGO mirrors be coated simutaneously with planetary rotation and masking to ensure the thickness uniformity (all Zernike poly terms <0.5nm)
Ion source:
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Mechanical loss of tantala(un-doped) with heat treated at 600oC at several frequencies.
I W Martin et al., “Effect of heat treatment on mechanical dissipation in Ta2O5 coatings”, Class. Quantum
Workshop on Gravitational Wave activities in Taiwan (GWTW) January 15, 2017 • Academia Sinica, Institute of Physics
Ion beam sputter nL：SiO2 nH：Ta2O5 with post-deposition annealing
Historical: Request of mirrors with very low optical loss for high precision ring-laser gyroscope back in late 70’s à invention of applying ion beam to sputter deposition laser mirror at Litton Systems (1979) à very large area for mirrors of laser gravitational wave detector in 2000’s with low optical loss + low mechanical loss
http://www.aerospaceweb.org/question/weapons/q0187.shtml http://www.defence-industries.com/company/army/precision-optics-optomechanical-assemblies/wzw-optic http://www.batop.de/information/r_Bragg.html http://www.ligo.caltech.edu/LIGO_web/9901news/9901han.html
Low optical loss Low mechanical loss
Higher index contrast->less number