Silicon-based optical mirror coatings for ultrahigh precision metrology and sensing

Steinlechner, J., Martin, I.W. , Bell, A.S. , Hough, J. , Fletcher, M., Murray, P.G. , Robie, R., Rowan, S. and Schnabel, R. (2018) Silicon-based optical mirror coatings for ultrahigh precision metrology and sensing. Physical Review Letters, 120(26), 263602. (doi: 10.1103/PhysRevLett.120.263602)

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Thermal noise of highly-reflective mirror coatings is a major limit to the sensitivity of many precision laser experiments with strict requirements such as low optical absorption. Here we investigate amorphous silicon and silicon nitride as an alternative to the currently used combination of coating materials, silica and tantala. We demonstrate an improvement by a factor of ≈55 with respect to the lowest so far reported optical absorption of amorphous silicon at near-infrared wavelengths. This reduction was achieved via a combination of heat treatment, final operation at low temperature and a wavelength of \unit[2]{μm} instead of the more commonly used \unit[1550]{nm}. Our silicon-based coating offers a factor of 12 thermal noise reduction compared to the performance possible with silica and tantala at \unit[20]{K}. In gravitational-wave detectors, a noise reduction by a factor of 12 corresponds to an increase in the average detection rate by three orders of magnitude (≈123).

Item Type:Articles
Additional Information:We are grateful for financial support from STFC (ST/ N005422/1), from the Royal Society (RG110331), from the ERC project MassQ (Grant Agreement No. 339897) and from the University of Glasgow. I. W. M. is supported by a Royal Society Research Fellowship.
Glasgow Author(s) Enlighten ID:Rowan, Professor Sheila and Robie, Raymond and Bell, Dr Angus and Martin, Dr Iain and Hough, Professor James and FLETCHER, MARK and Steinlechner, Dr Jessica and Murray, Dr Peter
Authors: Steinlechner, J., Martin, I.W., Bell, A.S., Hough, J., Fletcher, M., Murray, P.G., Robie, R., 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 Letters
Publisher:American Physical Society
ISSN (Online):1079-7114
Copyright Holders:Copyright © 2018 American Physical Society
First Published:First published in Physical Review Letters 120(26): 263602
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 & Technology Facilities Council (STFC)ST/L000946/1S&E P&A - PHYSICS & ASTRONOMY
591721Optical characterisation of silicon and mirror materials for gravitational astronomy.Iain MartinThe Royal Society (ROYSOC)RG110331S&E P&A - PHYSICS & ASTRONOMY