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Zirconia-titania-doped tantala optical coatings for low mechanical loss Bragg mirrors

Lalande, Émile and Lussier, Alexandre W. and Lévesque, Carl and Ward, Marianne and Baloukas, Bill and Martinu, Ludvik and Vajente, Gabriele and Billingsley, Garilynn and Ananyeva, Alena and Bassiri, Riccardo and Fejer, Martin M. and Schiettekatte, François (2021) Zirconia-titania-doped tantala optical coatings for low mechanical loss Bragg mirrors. Journal of Vacuum Science and Technology A, 39 (4). Art. No. 043416. ISSN 0734-2101.

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The noise caused by internal mechanical dissipation in high refractive index amorphous thin films in dielectric mirrors is an important limitation for gravitational wave detection. The objective of this study is to decrease this noise spectral density, which is linearly dependent on such dissipation and characterized by the loss angle of Young’s modulus, by adding zirconia to titania-doped tantala, from which the current mirrors for gravitational wave detection are made. The purpose of adding zirconia is to raise the crystallization temperature, which allows the material to be more relaxed by raising the practical annealing temperature. The Ta, Ti, and Zr oxides are deposited by reactive magnetron sputtering in an Ar:O₂ atmosphere using radio frequency and high power impulse plasma excitation. We show that, thanks to zirconia, the crystallization temperature rises by more than 150°C, which allows one to obtain a loss angle of 2.5×10⁻⁴, that is, a decrease by a factor of 1.5 compared to the current mirror high-index layers. However, due to a difference in the coefficient of thermal expansion between the thin film and the silica substrate, cracks appear at high annealing temperature. In response, a silica capping layer is applied to increase the temperature of crack formation by 100°C.

Item Type:Article
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URLURL TypeDescription
Vajente, Gabriele0000-0002-7656-6882
Billingsley, Garilynn0000-0002-4141-2744
Fejer, Martin M.0000-0002-5512-1905
Additional Information:© 2021 The Author(s). Published under an exclusive license by the AVS. Submitted: 7 April 2021 · Accepted: 25 May 2021 · Published Online: 10 June 2021. This paper is a part of the Special Topic Collection on Functional Coatings. The work performed at U. Montréal and Polytechnique Montréal was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canadian Foundation for Innovation (CFI), and the Fonds de recherche Québec, Nature et technologies (FQRNT) through the Regroupement Québécois sur les matériaux de pointe (RQMP). The authors thank S. Roorda, M. Chicoine, R. Shink, and L. Godbout from U. Montréal and F. Turcot from Polytechnique Montréal for fruitful discussions and technical support. They also thank their colleagues within the LIGO Scientific Collaboration for advice and support. LIGO was constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the National Science Foundation and operates under Cooperative Agreement No. PHY-0757058. Advanced LIGO was built under Award No. PHY-0823459. M. Fejer and R. Bassiri acknowledge the support of the LSC Center for Coatings Research, jointly funded by the National Science Foundation (NSF) and the Gordon and Betty Moore Foundation (GBMF), in particular through NSF Grant No. PHY-1708175 and GBMF Grant No. 6793. This paper has LIGO Document No. LIGO-P2000523. DATA AVAILABILITY. The data that support the findings of this study are available from the corresponding author upon reasonable request.
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Canada Foundation for InnovationUNSPECIFIED
Fonds de recherche du Québec – Nature et technologies (FRQNT)UNSPECIFIED
Gordon and Betty Moore FoundationGBMF6793
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Other Numbering System NameOther Numbering System ID
LIGO DocumentP2000523
Issue or Number:4
Record Number:CaltechAUTHORS:20210610-153552571
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109477
Deposited By: George Porter
Deposited On:11 Jun 2021 14:19
Last Modified:11 Jun 2021 14:19

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