GRAvitational-waves Science&technology Symposium (GRASS 2019)

Session

Ultra-low-noise optical coatings

COAT

24 Oct 2019, 14:00

Sala Paladini (Palazzo Moroni, Padova)

38. Numerical modelling of low-T oxide film growth

Anael Lemaitre

24/10/2019, 14:20

Oxide films are customarily manufactured using physical vapor deposition (PVD) at or near room temperature. In such conditions, the covalent bonds formed by oxide atoms (or order a few eV's) cannot be broken by thermal agitation; atoms only rearrange during the impacts of deposited particles. This process hampers the formation of crystalline domains and thus facilitates the growth of...

14. Modeling and simulations of current and prospective coating materials

Dr Francesco Puosi (Dip. di Fisica - Università di Pisa, INFN)

24/10/2019, 14:40

The development of thin-film coatings with lower mechanical losses is of critical importance for the performance of future generations of interferometric gravitational-wave detectors. Significant experimental effort has led to improvements during these years and currently the most advanced technology is the one of amorphous coatings. Yet, there is still a lack of fundamental understanding of...

19. Multimaterial Coatings for 3rd Generation Gravitational Wave Detectors

Peter Murray (SUPA University of Glasgow)

24/10/2019, 15:05

Thermal noise associated with the mechanical loss of highly reflective mirror coatings is a critical limiting factor to the sensitivity of interferometric gravitational-wave detectors. Several alternative coating materials have been shown to have low mechanical loss, but however, due to their high optical absorption, cannot be implemented in upgrades to these detectors.

New multimaterial...

8. Dissipation in a Tantala film from 10K to 150K from thermal noise measurements

Ludovic Bellon (Univ Lyon, ENS Lyon, UCBL, CNRS, Laboratoire de Physique (LPENSL))

24/10/2019, 15:30

We study the dissipation φ of a silicon µ-cantilever coated with 300nm of Tantala. From the thermal noise spectra, a fit of 10 resonances for flexion modes, and 6 resonances for torsion modes can be performed, giving access to φ from 2 kHz to 600 kHz. Dissipation presents a weak maximum around 50 K in temperature, and is a slowly increasing function of frequency (power law $f^α$ with α~0.06)....

25. Annealing effects on the mechanical losses of fluorides thin films

Matteo Bischi (Istituto Nazionale di Fisica Nucleare, Università di Urbino)

24/10/2019, 15:55

Fluorides like MgF2 and AlF3 have the lowest refractive index among the known coating materials; using them in a high-reflection (HR) Bragg mirror instead of SiO2, one could reduce the total HR coating thickness and hence its coating thermal noise.
A succession of annealing treatments at different temperatures (but with the same duration) were performed on a silica disk coated with MgF2. The...