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Bulk and shear mechanical loss of titania–doped tantala

Abernathy, Matthew and Harry, Gregory and Newport, Jonathan and Fair, Hannah and Kinley-Hanlon, Maya and Hickey, Samuel and Jiffar, Isaac and Gretarsson, Andri and Penn, Steve and Bassiri, Riccardo and Gustafson, Eric and Martin, Iain and Rowan, Sheila and Hough, Jim (2018) Bulk and shear mechanical loss of titania–doped tantala. Physics Letters A, 382 (33). pp. 2282-2288. ISSN 0375-9601. doi:10.1016/j.physleta.2017.08.007.

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We report on the mechanical loss from bulk and shear stresses in thin film, ion beam deposited, titania–doped tantala. The numerical values of these mechanical losses are necessary to fully calculate the Brownian thermal noise in precision optical cavities, including interferometric gravitational wave detectors like LIGO. We found the values from measuring the normal mode mechanical quality factors, Q's, in the frequency range of about 2000-10,000 Hz, of silica disks coated with titania–doped tantala coupled with calculating the elastic energy in shear and bulk stresses in the coating using a finite element model. We fit the results to both a frequency independent and frequency dependent model and find ϕ_(shear)=(8.3±1.1)×10^(−4), ϕ_(bulk)=(6.6±3.8)×10^(−4) with a frequency independent model and ϕ_(shear)(f)=(5.0±0.7)×10^(−4)+(5.4±1.1)×10^(−8)f, ϕ_(bulk)(f)=(11±2.8)×10^(−4)−(8.7±4.7)×10^(−8)f with a frequency dependent (linear) model. The ratio of these values suggest that modest improvement in the coating thermal noise may be possible in future gravitational wave detector optics made with titania–doped tantala as the high index coating material by optimizing the coating design to take advantage of the two different mechanical loss angles.

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Additional Information:© 2017 Published by Elsevier B.V. Received 15 May 2017, Accepted 3 August 2017, Available online 18 August 2017.
Issue or Number:33
Record Number:CaltechAUTHORS:20170825-160837330
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Official Citation:Matthew Abernathy, Gregory Harry, Jonathan Newport, Hannah Fair, Maya Kinley-Hanlon, Samuel Hickey, Isaac Jiffar, Andri Gretarsson, Steve Penn, Riccardo Bassiri, Eric Gustafson, Iain Martin, Sheila Rowan, Jim Hough, Bulk and shear mechanical loss of titania-doped tantala, Physics Letters A, Volume 382, Issue 33, 2018, Pages 2282-2288, ISSN 0375-9601, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:80820
Deposited By: Tony Diaz
Deposited On:28 Aug 2017 14:50
Last Modified:15 Nov 2021 19:38

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