Mapping the optical absorption of a substrate-transferred crystalline AlGaAs coating at 1.5 µm

Steinlechner, J., Martin, I. W., , Bell, A. , Cole, G., Hough, J. , Penn, S., Rowan, S. and Steinlechner, S. (2015) Mapping the optical absorption of a substrate-transferred crystalline AlGaAs coating at 1.5 µm. Classical and Quantum Gravity, 32(10), 105008. (doi: 10.1088/0264-9381/32/10/105008)

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The sensitivity of 2nd and 3rd generations of interferometric gravitational wave detectors will be limited by thermal noise of the test-mass mirrors and highly reflective coatings. Recently developed crystalline coatings show a promising thermal noise reduction compared to presently used amorphous coatings. However, stringent requirements apply to the optical properties of the coatings as well. We have mapped the optical absorption of a crystalline AlGaAs coating which is optimized for high reflectivity for a wavelength of 1064nm. The absorption was measured at 1550nm where the coating stack transmits approximately 70% of the laser light. The measured absorption was lower than (30.2 +/- 11.1)ppm which is equivalent to (3.6 +/- 1.3)ppm for a coating stack that is highly reflective at 1530nm. While this is a very promising low absorption result for alternative low--loss coating materials, further work will be necessary to reach the requirements of <1ppm for future gravitational wave detectors. Jessica Steinlechner, Iain W Martin, Angus Bell, Garrett Cole, Jim Hough, Steven Penn, Sheila Rowan, Sebastian Steinlechner

Item Type:Articles
Glasgow Author(s) Enlighten ID:Steinlechner, Dr Sebastian and Rowan, Professor Sheila and Penn, Professor Steven and Bell, Dr Angus and Martin, Dr Iain and Steinlechner, Dr Jessica and Hough, Professor James
Authors: Steinlechner, J., Martin, I. W.,, Bell, A., Cole, G., Hough, J., Penn, S., Rowan, S., and Steinlechner, S.
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:Classical and Quantum Gravity
Publisher:Institute of Physics
ISSN (Online):1361-6382
Copyright Holders:Copyright © 2015 The Authors
First Published:First published in Classical and Quantum Gravity 32(10):105008
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
591721Optical characterisation of silicon and mirror materials for gravitational astronomy.Iain MartinRoyal Society (ROYSOC)RG110331S&E P&A - PHYSICS & ASTRONOMY
624341Investigations in Gravitational Radiation / Particle Astrophysics Capital equipmentSheila RowanScience & Technologies Facilities Council (STFC)ST/L000946/1S&E P&A - PHYSICS & ASTRONOMY