Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published February 15, 2020 | Published + Submitted
Journal Article Open

A method for the experimental measurement of bulk and shear loss angles in amorphous thin films


Brownian thermal noise is a limiting factor for the sensitivity of many high precision metrology applications, among other gravitational-wave detectors. The origin of Brownian noise can be traced down to internal friction in the amorphous materials that are used for the high reflection coatings. To properly characterize the internal friction in an amorphous material, one needs to consider separately the bulk and shear losses. In most of previous works the two loss angles were considered equal, although without any first principle motivation. In this work we present a method that can be used to extract the material bulk and shear loss angles, based on current state-of-the-art coating ring-down measurement systems. We also show that for titania-doped tantala, a material commonly used in gravitational-wave detector coatings, the experimental data strongly favor a model with two different and distinct loss angles, over the simpler case of one single loss angle.

Additional Information

© 2020 American Physical Society. Received 27 November 2019; accepted 5 February 2020; published 24 February 2020. LIGO was constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the United States National Science Foundation under Grant No. PHY-0757058. This work was also supported by the Center for Coating Research, NSF Grants No. PHY-1708010 and No. PHY-1710957 and by the LIGO Laboratory, NSF Grant No. PHY-1764464. The authors are grateful for computational resources provided by the LIGO Laboratory and supported by the National Science Foundation Grants No. PHY-0757058 and No. PHY-0823459. This paper has LIGO document number P1900336.

Attached Files

Submitted - 1911.12277.pdf

Published - PhysRevD.101.042004.pdf


Files (2.4 MB)
Name Size Download all
1.1 MB Preview Download
1.3 MB Preview Download

Additional details

August 19, 2023
August 19, 2023