@article{94d8e14853d74772afa1cc6f318d8290,
title = "Thermal detuning of a bichromatic narrow linewidth optical cavity",
abstract = "In the Advanced Virgo+ interferometric gravitational-wave detector, the length control of the Fabry-P{\'e}rot cavities in the arms and of the detuned filter cavity, used for generating frequency-dependent squeezing, uses an auxiliary green beam at half of the operation laser wavelength (1064 nm). While operating the filter cavity with such a bichromatic control scheme for tens of hours, we observed that the mirror reflection phase shift of the fields at the two wavelengths responds differently to temperature changes in the mirrors, causing a change in the relative resonance condition of the two beams. In this paper we show that this thermal detuning effect can be explained by considering the thermomechanical properties of the mirror coating. Our experimental measurements are in good agreement with the theoretical predictions and allow us to drive requirements on the bicolor coating design and mirror temperature stability for long-term stable cavity control.",
author = "Bonavena, {L. D.} and M. Lequime and M. Vardaro and Y. Zhao and M. Barsuglia and M. Bawaj and A. Bertolini and R. Bonnand and E. Capocasa and {De Laurentis}, M. and J. Ding and {Di Pace}, S. and R. Flaminio and B. Garaventa and A. Grimaldi and Y. Guo and Jacquet, {P. E.} and A. Masserot and M. Mehmet and R. Passaquieti and L. Pinard and E. Polini and V. Sequino and F. Sorrentino and M. Tacca and H. Vahlbruch and Zendri, {J. P.}",
note = "Funding Information: The authors gratefully acknowledge the support of the Max Planck Society, Leibniz Universit\u00E4t Hannover and Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through project Grant No. VA 1031/1-1 and Germany's Excellence Strategy \u2013 EXC-2123 QuantumFrontiers \u2013 390837967 for the construction, installation, and operation of the squeezed-light source. The authors are also grateful to the Genova, Napoli, Padova, Perugia Roma I, and Trento Univeristies and sections of the Italian National Institute of Nuclear Physics (INFN) for the realization of the squeezed vacuum source bench among with the PLLs and the diagnostic homodyne electronics. We also thank the Particle Physics Laboratory of Annecy (LAPP) (F) for providing the suspended optical benches, the clean rooms around them, and the data acquisition system, the Dutch National Institute for Atomic Physics (Nikhef) for supplying the cavity vacuum system, the mechanical suspension for both the in-vacuum benches and the cavity mirrors, and the rf quadrant photodiode readout, the Laboratoire des Materiaux Avanc\u00E9s (LMA) of Lyon (F) for the realization of the optical coatings, the Institute of Cosmos Sciences (ICCUB) for providing the in-vacuum position-sensitive detector, the Institute of High Energy Physics (IFAE) of Barcelona (E) for the realization and the installation of the vacuum baffle, the Rome Tor-Vergata group for the ring heaters, the Perugia group for the assembly of the mirrors, and the Napoli group for optical lever position sensors. Special thanks go to the staff of the European Gravitational Observatory (EGO) for the relevant role in the logistics, in the implementation of the structural changes, in the electronics cabling, in the development of customized electronics, and in the supply of the low-loss Faraday isolators. This work has been also supported by LabEx UnivEarthS (ANR-10-LABX-0023 and ANR-18-IDEX-0001). Publisher Copyright: {\textcopyright} 2024 American Physical Society.",
year = "2024",
month = apr,
day = "11",
doi = "10.1103/PhysRevA.109.043709",
language = "English",
volume = "109",
journal = "Physical Review A",
issn = "1050-2947",
publisher = "American Physical Society",
number = "4",
}