Thermal noise of folding mirrors

Heinert, D., Craig, K., Grote, H., Hild, S., Lück, H., Nawrodt, R., Simakov, D.A., Vasilyev, D.V., Vyatchanin, S. P. and Wittel, H. (2014) Thermal noise of folding mirrors. Physical Review D, 90(4), 042001. (doi: 10.1103/PhysRevD.90.042001)

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Publisher's URL: http://dx.doi.org/10.1103/PhysRevD.90.042001

Abstract

Current gravitational wave detectors rely on the use of Michelson interferometers. One crucial limitation of their sensitivity is the thermal noise of their optical components. Thus, for example fluctuational deformations of the mirror surface are probed by a laser beam being reflected from the mirrors at normal incidence. Thermal noise models are well evolved for that case but mainly restricted to single reflections. In this work we present the effect of two consecutive reflections under a non-normal incidence onto mirror thermal noise. This situation is inherent to detectors using a geometrical folding scheme such as GEO\,600. We revise in detail the conventional direct noise analysis scheme to the situation of non-normal incidence allowing for a modified weighting funtion of mirror fluctuations. An application of these results to the GEO\,600 folding mirror for Brownian, thermoelastic and thermorefractive noise yields an increase of displacement noise amplitude by 20\% for most noise processes. The amplitude of thermoelastic substrate noise is increased by a factor 4 due to the modified weighting function. Thus the consideration of the correct weighting scheme can drastically alter the noise predictions and demands special care in any thermal noise design process.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Nawrodt, Dr Ronny and Hild, Professor Stefan and Craig, Mr Kieran
Authors: Heinert, D., Craig, K., Grote, H., Hild, S., Lück, H., Nawrodt, R., Simakov, D.A., Vasilyev, D.V., Vyatchanin, S. P., and Wittel, H.
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 © 2014 American Physical Society
First Published:First published in Physical Review D 90(4):042001
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
624341Investigations in Gravitational Radiation / Particle Astrophysics Capital equipmentSheila RowanScience & Technologies Facilities Council (STFC)ST/L000946/1S&E P&A - PHYSICS & ASTRONOMY