Details
| Original language | English |
|---|---|
| Pages (from-to) | 36731-36740 |
| Number of pages | 10 |
| Journal | Optics express |
| Volume | 27 |
| Issue number | 25 |
| Early online date | 4 Dec 2019 |
| Publication status | Published - 9 Dec 2019 |
Abstract
Precision interferometry is the leading method for extremely sensitive measurements in gravitational wave astronomy. Thermal noise of dielectric coatings poses a limitation to the sensitivity of these interferometers. To decrease coating thermal noise, new crystalline GaAs/AlGaAs multilayer mirrors have been developed. To date, the surface figure and thickness uniformity of these alternative low-loss coatings has not been investigated. Surface figure errors, for example, cause small angle scattering and thereby limit the sensitivity of an interferometer. Here we measure the surface figure of highly reflective, substrate-transferred, crystalline GaAs/AlGaAs coatings with a custom scanning reflectance system. We exploit the fact that the reflectivity varies with the thickness of the coating. To increase penetration into the coating, we used a 1550 nm laser on a highly reflective coating designed for a center wavelength of 1064 nm. The RMS thickness variation of a two inch optic was measured to be 0.41 ± 0.05 nm. This result is within 10% of the thickness uniformity, of 0.37 nm RMS, achieved with ion-beam sputtered coatings for the aLIGO detector. We additionally measured a lower limit of the laser induced damage threshold of 64 MW/cm2 for GaAs/AlGaAs coatings at a wavelength of 1064 nm.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Atomic and Molecular Physics, and Optics
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In: Optics express, Vol. 27, No. 25, 09.12.2019, p. 36731-36740.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Thickness uniformity measurements and damage threshold tests of large-area GaAs/AlGaAs crystalline coatings for precision interferometry
AU - Koch, P.
AU - Cole, G. D.
AU - Deutsch, C.
AU - Follman, D.
AU - Heu, P.
AU - Kinley-Hanlon, M.
AU - Kirchhoff, R.
AU - Leavey, S.
AU - Lehmann, J.
AU - Oppermann, P.
AU - Rai, A. K.
AU - Tornasi, Z.
AU - Wöhler, J.
AU - Wu, D. S.
AU - Zederbauer, T.
AU - Lück, H.
N1 - Funding information: Deutsche Forschungsgemeinschaft (EXC-2123/1); Max Planck Research School on Gravitational Wave Astronomy.
PY - 2019/12/9
Y1 - 2019/12/9
N2 - Precision interferometry is the leading method for extremely sensitive measurements in gravitational wave astronomy. Thermal noise of dielectric coatings poses a limitation to the sensitivity of these interferometers. To decrease coating thermal noise, new crystalline GaAs/AlGaAs multilayer mirrors have been developed. To date, the surface figure and thickness uniformity of these alternative low-loss coatings has not been investigated. Surface figure errors, for example, cause small angle scattering and thereby limit the sensitivity of an interferometer. Here we measure the surface figure of highly reflective, substrate-transferred, crystalline GaAs/AlGaAs coatings with a custom scanning reflectance system. We exploit the fact that the reflectivity varies with the thickness of the coating. To increase penetration into the coating, we used a 1550 nm laser on a highly reflective coating designed for a center wavelength of 1064 nm. The RMS thickness variation of a two inch optic was measured to be 0.41 ± 0.05 nm. This result is within 10% of the thickness uniformity, of 0.37 nm RMS, achieved with ion-beam sputtered coatings for the aLIGO detector. We additionally measured a lower limit of the laser induced damage threshold of 64 MW/cm2 for GaAs/AlGaAs coatings at a wavelength of 1064 nm.
AB - Precision interferometry is the leading method for extremely sensitive measurements in gravitational wave astronomy. Thermal noise of dielectric coatings poses a limitation to the sensitivity of these interferometers. To decrease coating thermal noise, new crystalline GaAs/AlGaAs multilayer mirrors have been developed. To date, the surface figure and thickness uniformity of these alternative low-loss coatings has not been investigated. Surface figure errors, for example, cause small angle scattering and thereby limit the sensitivity of an interferometer. Here we measure the surface figure of highly reflective, substrate-transferred, crystalline GaAs/AlGaAs coatings with a custom scanning reflectance system. We exploit the fact that the reflectivity varies with the thickness of the coating. To increase penetration into the coating, we used a 1550 nm laser on a highly reflective coating designed for a center wavelength of 1064 nm. The RMS thickness variation of a two inch optic was measured to be 0.41 ± 0.05 nm. This result is within 10% of the thickness uniformity, of 0.37 nm RMS, achieved with ion-beam sputtered coatings for the aLIGO detector. We additionally measured a lower limit of the laser induced damage threshold of 64 MW/cm2 for GaAs/AlGaAs coatings at a wavelength of 1064 nm.
UR - http://www.scopus.com/inward/record.url?scp=85076443577&partnerID=8YFLogxK
U2 - 10.1364/OE.27.036731
DO - 10.1364/OE.27.036731
M3 - Article
C2 - 31873446
AN - SCOPUS:85076443577
VL - 27
SP - 36731
EP - 36740
JO - Optics express
JF - Optics express
SN - 1094-4087
IS - 25
ER -