Murray, P. G. et al. (2017) Cryogenic mechanical loss of a single-crystalline GaP coating layer for precision measurement applications. Physical Review D, 95(4), 042004. (doi: 10.1103/PhysRevD.95.042004)
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Abstract
The first direct observations of gravitational waves have been made by the Advanced LIGO detectors. However, the quest to improve the sensitivities of these detectors remains, and epitaxially grown single-crystal coatings show considerable promise as alternatives to the ion-beam sputtered amorphous mirror coatings typically used in these detectors and other such precision optical measurements. The mechanical loss of a 1 μm thick single-crystalline gallium phosphide (GaP) coating, incorporating a buffer layer region necessary for the growth of high quality epitaxial coatings, has been investigated over a broad range of frequencies and with fine temperature resolution. It is shown that at 20 K the mechanical loss of GaP is a factor of 40 less than an undoped tantala film heat-treated to 600 °C and is comparable to the loss of a multilayer GaP/AlGaP coating. This is shown to translate into possible reductions in coating thermal noise of a factor of 2 at 120 K and 5 at 20 K over the current best IBS coatings (alternating stacks of silica and titania-doped tantala). There is also evidence of a thermally activated dissipation process between 50 and 70 K.
| Item Type: | Articles |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Rowan, Professor Sheila and Martin, Dr Iain and Hough, Professor James and Bassiri, Mr Riccardo and Murray, Dr Peter |
| Authors: | Murray, P. G., Martin, I. W., Craig, K., Hough, J., Rowan, S., Bassiri, R., Fejer, M. M., Harris, J. S., Lantz, B. T., Lin, A. C., Markosyan, A. S., and Route, R. K. |
| College/School: | College of Science and Engineering > School of Physics and Astronomy |
| Research Centre: | College of Science and Engineering > School of Physics and Astronomy > Institute for Gravitational Research |
| Journal Name: | Physical Review D |
| Publisher: | American Physical Society |
| ISSN: | 1550-7998 |
| ISSN (Online): | 1550-2368 |
| Published Online: | 17 February 2017 |
| Copyright Holders: | Copyright © 2017 The Authors |
| First Published: | First published in Physical Review D 95(4):042004 |
| Publisher Policy: | Reproduced under a Creative Commons License |
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