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Designing a Low-Loss High-Reflectivity Mirror for Gravitational-Wave Detectors by Combining a Dielectric Metasurface and a Multilayer Stack

Edith Hartmann1,*, Michel Lequime1, Jérôme Degallaix2, Michael T. Hartman1, Paul Rouquette1, Claude Amra1, and Myriam Zerrad1

  • *Contact author: edith.hartmann@fresnel.fr
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Phys. Rev. Lett. 137, 181403 – Published 30 October, 2026

DOI: https://doi.org/10.1103/4rvc-zcp1

Abstract

The design of low-mechanical-loss, high reflectivity mirrors is crucial in the development of the next generation of gravitational-wave observatories. Currently, the amorphous multilayer reflective coatings which are deposited at the surface of the test masses in interferometric gravitational-wave detectors present a major limiting factor in detector sensitivity due to their thermal noise. These coatings require a large number of thin layers to achieve ultrahigh reflectivity. However, the thermal noise generated by this type of stack increases with the number of layers used. These dielectric mirrors represent a mature technology, with current research producing only incremental improvements, highlighting the need for new technical solutions that can address this specific issue. Here, we provide insights into the expected performance of mirrors that combine a resonant metasurface with a multilayer stack. The suggested mirror design ensures the high reflectivity required for interferometric gravitational wave detectors, while using fewer layers of properly selected materials. As a result, it significantly reduces the total coating thickness, making it a promising option for reducing thermal noise as well.

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Phys. Rev. Lett. 137, 181403– Published 30 October, 2026
  • Received 27 March 2026
  • Revised 17 July 2026
  • Accepted 8 October 2026
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