Molecular Dynamics Study of Optical Coatings of TiO₂–ZrO₂–Doped GeO₂ for Gravitational-Wave Detectors

A decade after the Nobel Prize–winning discovery of gravitational waves from a binary black hole merger, the Advanced LIGO detectors—now in their fourth observing run (O4)—routinely detect black hole mergers, roughly one every three days, with a total of about 300 events to date. The next generation of observatories will greatly expand the observable universe, potentially enabling the detection of signals from the early cosmos. Achieving the design sensitivity of these future detectors, alongside advances in several other technologies, requires significant improvement in mirror coatings.

In this poster, I will present a computational study of a candidate mirror-coating material: amorphous GeO₂–TiO₂–ZrO₂ (GTZO). Using ab initio molecular dynamics (AIMD) and machine-learning interatomic potentials (MLIP), we investigate the atomic structure of amorphous GTZO. Structural modifications induced by increasing concentrations of ZrO₂ will be analyzed to understand whether and how ZrO₂ suppresses crystallization in TiO₂-doped GeO₂ coatings during post-deposition annealing.