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 (30.2 +/- 11.1) ppm, which is equivalent to (3.6 +/- 1.3) 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 < 1 ppm for future GW detectors.
Original language | English |
---|---|
Article number | 105008 |
Number of pages | 12 |
Journal | Classical and Quantum Gravity |
Volume | 32 |
Issue number | 10 |
DOIs | |
Publication status | Published - 21 May 2015 |
Externally published | Yes |
Keywords
- gravitational wave detectors
- absorption
- crystalline coating
- SILICON