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arXiv · 2512.17395

In situ substrate birefringence characterization in gravitational wave detectors using a heterodyne polarimetry method

Satoshi Tanioka·Terri Pearce·Yuta Michimura·Kazuhiro Agatsuma·Martin Van Beuzekom·Alberto Vecchio·Stephen Webster·Matteo Leonardi·Keiko Kokeyama
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Abstract

High-quality test mass substrates play essential roles in laser interferometric gravitational wave detectors. Inhomogeneous birefringence distribution in test mass substrates, however, can degrade the sensitivity of the detector by introducing the optical loss and disturbing the interferometer controls. In this paper, we present a heterodyne polarimetry method that enables in situ birefringence characterizations, hence diagnosing the gravitational wave interferometer. We experimentally demonstrate the proposed method with a tabletop setup. We also discuss its applicability to current and future gravitational wave detectors and the detectable limit.

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Satoshi Tanioka, Terri Pearce, Yuta Michimura, Kazuhiro Agatsuma, Martin Van Beuzekom, Alberto Vecchio, Stephen Webster, Matteo Leonardi, Keiko Kokeyama. 2025-12-19. In situ substrate birefringence characterization in gravitational wave detectors using a heterodyne polarimetry method. https://doi.org/10.1364/ao.588208

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