Cryogenic mechanical loss of a single-crystalline GaP coating layer for precision measurement applications

Murray, P. G.; Martin, I. W.; Craig, K.; Hough, J.; Rowan, S.; Bassiri, R.; Fejer, M. M.; Harris, James S.; Lantz, B.; Lin, A. C.; Markosyan, A. S.; Route, R.

doi:10.1103/physrevd.95.042004

Cited by 7 publications

(7 citation statements)

References 54 publications

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“…Several potential coating choices are being actively researched for use in cryogenic third-generation detectors, such as ionbeam sputtered amorphous oxides, non-oxides, and crystalline thin films of III-V semiconductor materials. Two promising crystalline coating options are epitaxially grown multilayers of the AlGaAs/GaAs system (Cole et al 2008; or the AlGaP/GaP system (Lin et al 2013;Cumming et al 2015;Murray et al 2017). AlGaAs/GaAs coatings exhibit exceptionally low mechanical loss, optical absorption, and scatter.…”

Section: Building Nemomentioning

confidence: 99%

Neutron Star Extreme Matter Observatory: A kilohertz-band gravitational-wave detector in the global network

Ackley

Adya

Agrawal

et al. 2020

Publ. Astron. Soc. Aust.

187

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Gravitational waves from coalescing neutron stars encode information about nuclear matter at extreme densities, inaccessible by laboratory experiments. The late inspiral is influenced by the presence of tides, which depend on the neutron star equation of state. Neutron star mergers are expected to often produce rapidly rotating remnant neutron stars that emit gravitational waves. These will provide clues to the extremely hot post-merger environment. This signature of nuclear matter in gravitational waves contains most information in the 2–4 kHz frequency band, which is outside of the most sensitive band of current detectors. We present the design concept and science case for a Neutron Star Extreme Matter Observatory (NEMO): a gravitational-wave interferometer optimised to study nuclear physics with merging neutron stars. The concept uses high-circulating laser power, quantum squeezing, and a detector topology specifically designed to achieve the high-frequency sensitivity necessary to probe nuclear matter using gravitational waves. Above 1 kHz, the proposed strain sensitivity is comparable to full third-generation detectors at a fraction of the cost. Such sensitivity changes expected event rates for detection of post-merger remnants from approximately one per few decades with two A+ detectors to a few per year and potentially allow for the first gravitational-wave observations of supernovae, isolated neutron stars, and other exotica.

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Section: Building Nemomentioning

confidence: 99%

Neutron Star Extreme Matter Observatory: A kilohertz-band gravitational-wave detector in the global network

Ackley

Adya

Agrawal

et al. 2020

Publ. Astron. Soc. Aust.

187

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“…Mono-crystalline semiconductors grown by molecular-beam epitaxy like GaAs/AlGaAs [46] and GaP/AlGaP [47] coatings feature low internal friction (φ c ≤ 10 −4 ) at ambient and cryogenic temperature. Furthermore, GaAs/AlGaAs coatings have competitive optical properties [48] when compared with current state-of-the art IBS coatings [4].…”

Section: Crystalline Coatingsmentioning

confidence: 99%

Progress in the measurement and reduction of thermal noise in optical coatings for gravitational-wave detectors

et al. 2020

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Coating thermal noise is a fundamental limit for precision experiments based on optical and quantum transducers. In this review, after a brief overview of the techniques for coating thermal noise measurements, we present the latest world-wide research activity on low-noise coatings, with a focus on the results obtained at the Laboratoire des Matériaux Avancés. We report new updated values for the Ta 2 O 5 , Ta 2 O 5 -TiO 2 and SiO 2 coatings of the Advanced LIGO, Advanced Virgo and KAGRA detectors, and new results from sputtered Nb 2 O 5 , TiO 2 -Nb 2 O 5 , Ta 2 O 5 -ZrO 2 , MgF 2 , AlF 3 and silicon nitride coatings. Amorphous silicon, crystalline coatings, high-temperature deposition, multi-material coatings and composite layers are also briefly discussed, together with the latest developments of structural analyses and models. The issue of coating thermal noiseThe Laboratoire des Matériaux Avancés (LMA, now a division of the newly created Institut de Physique des 2 Infinis de Lyon) has provided the current high-reflection (HR) and anti-reflective (AR) coatings of the most critical optics of Advanced LIGO [1], Advanced Virgo [2] and KAGRA [3]. In these gravitational-wave (GW) interferometers, large and massive suspended mirrors (typically with ∅ = 35 cm, t = 20 cm, m = 40 kg) form the km-long resonant Fabry-Perot cavities where the astrophysical signals are embedded in the laser beam phase. Their HR coatings are Bragg reflectors of alternate layers of ion-beam-sputtered (IBS) low-and high-refractive index materials, which feature outstanding optical properties [4]. At the same time, these amorphous coatings are the source of coating thermal noise (CTN), which is a severe limitation to the detector sensitivity [1,2].In GW interferometers, thermal noise arises from fluctuations of the mirror surface under the random motion of particles in coatings and substrates [5,6]. Its power spectral density is determined by the amount of internal friction within the mirror materials, via the fluctuationdissipation theorem [7]: the higher the elastic energy loss, the higher the thermal noise level. As the coating loss is usually several orders of magnitude larger than that of the substrate [8,9], CTN is the dominant source of noise in the mirrors.More generally, CTN is a fundamental limit for precision experiments based on optical and quantum transducers, such as opto-mechanical resonators [10], frequency standards [11] and quantum computers [12]. In the last two decades, a considerable research effort has been committed to the measurement and the reduction of CTN.

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“…However, to grow a mono-crystalline coating, the lattice structures and constants of the substrate material and of the two coating materials have to be matched. Two combinations have been investigated within the gravitational-wave community over the past years: GaAs/AlGaAs [57] and GaP/AlGaP [58][59][60].…”

Section: (F) Crystalline Coatingsmentioning

confidence: 99%

“…Crystalline coatings made of GaP and AlGaP are an interesting alternative to AlGaAs as they can be grown on crystalline silicon [58][59][60]. This would solve the size problem for gravitational-wave detectors and make even the substrate transfer, which involves a bonding procedure, unnecessary.…”

Section: (Ii) Gap/algapmentioning

confidence: 99%

Development of mirror coatings for gravitational-wave detectors

Steinlechner

2018

Phil. Trans. R. Soc. A.

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Gravitational waves are detected by measuring length changes between mirrors in the arms of kilometre-long Michelson interferometers. Brownian thermal noise arising from thermal vibrations of the mirrors can limit the sensitivity to distance changes between the mirrors, and, therefore, the ability to measure gravitational-wave signals. Thermal noise arising from the highly reflective mirror coatings will limit the sensitivity both of current detectors (when they reach design performance) and of planned future detectors. Therefore, the development of coatings with low thermal noise, which at the same time meet strict optical requirements, is of great importance. This article gives an overview of the current status of coatings and of the different approaches for coating improvement.This article is part of a discussion meeting issue 'The promises of gravitational-wave astronomy'.

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Cryogenic mechanical loss of a single-crystalline GaP coating layer for precision measurement applications

Cited by 7 publications

References 54 publications

Neutron Star Extreme Matter Observatory: A kilohertz-band gravitational-wave detector in the global network

Neutron Star Extreme Matter Observatory: A kilohertz-band gravitational-wave detector in the global network

Progress in the measurement and reduction of thermal noise in optical coatings for gravitational-wave detectors

Development of mirror coatings for gravitational-wave detectors

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