Mapping the optical absorption of a substrate-transferred crystalline AlGaAs coating at 1.5 μm. (27th April 2015)

• Record Type: Journal Article
• Authors: Steinlechner, Jessica; W Martin, Iain; Bell, Angus; Cole, Garrett; Hough, Jim; Penn, Steven; Rowan, Sheila; Steinlechner, Sebastian
• Is Part Of: Classical and quantum gravity. Volume 32:Number 10(2015:May)
• Publication Date: 2015-04-27
• Subjects: gravitational wave detectors -- absorption -- crystalline coating; Quantum gravity -- Periodicals; Gravitation -- Periodicals; Relativity (Physics) -- Periodicals; Space and time -- Periodicals; Periodicals; 521.1
• DOI: 10.1088/0264-9381/32/10/105008
• Languages: English
• ISSNs: 0264-9381

Abstract

Abstract: The sensitivity of second and third generations of interferometric gravitational wave (GW) detectors will be limited by the 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 that is optimized for high reflectivity for a wavelength of 1064 nm. The absorption was measured at 1530 nm, where the coating stack transmits approximately 70% of the laser light. The measured absorption was lower than ppm, which is equivalent to ppm for a coating stack that is highly reflective at 1530 nm. 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 ppm for future GW detectors.