Steinlechner, J., Martin, I. W. , Hough, J. , Krüger, C., Rowan, S. and Schnabel, R. (2015) Thermal noise reduction and absorption optimization via multimaterial coatings. Physical Review D, 91(4), 042001. (doi: 10.1103/PhysRevD.91.042001)
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Publisher's URL: http://dx.doi.org/10.1103/PhysRevD.91.042001
Abstract
Future gravitational wave detectors (GWDs) such as Advanced LIGO upgrades and the Einstein Telescope are planned to operate at cryogenic temperatures using crystalline silicon (cSi) test-mass mirrors at an operation wavelength of 1550 nm. The reduction in temperature in principle provides a direct reduction in coating thermal noise, but the presently used coating stacks which are composed of silica (SiO<sub>2</sub>) and tantala (Ta<sub>2</sub>O<sub>5</sub>) show cryogenic loss peaks which results in less thermal noise improvement than might be expected. Due to low mechanical loss at low temperature amorphous silicon (aSi) is a very promising candidate material for dielectric mirror coatings and could replace Ta<sub>2</sub>O<sub>5</sub>. Unfortunately, such an aSi/SiO<sub>2</sub> coating is not suitable for use in GWDs due to high optical absorption in aSi coatings. We explore the use of a three material based coating stack. In this multimaterial design the low absorbing Ta<sub>2</sub>O<sub>5</sub> in the outermost coating layers significantly reduces the incident light power, while aSi is used only in the lower bilayers to maintain low optical absorption. Such a coating design would enable a reduction of Brownian thermal noise by 25%. We show experimentally that an optical absorption of only (5.3±0.4) ppm at 1550 nm should be achievable.
| Item Type: | Articles |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Rowan, Professor Sheila and Martin, Dr Iain and Steinlechner, Dr Jessica and Hough, Professor James |
| Authors: | Steinlechner, J., Martin, I. W., Hough, J., Krüger, C., Rowan, S., and Schnabel, R. |
| 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 |
| Copyright Holders: | Copyright © 2015 American Physical Society |
| First Published: | First published in Physical Review D 91(4):042001 |
| Publisher Policy: | Reproduced in accordance with the copyright policy of the publisher. |
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