Phase shift in optical cavities could detect low-frequency gravitational waves – Physics World

Detecting Low-Frequency Gravitational Waves with Optical Cavities

A network of optical cavities could be used to detect gravitational waves in an unexplored range of frequencies, according to researchers in the UK.

Using existing technology, the team believes that astronomers could soon be searching for ripples in space-time across the milli-Hz frequency band at 10⁻⁵ Hz–1 Hz.

Current Detection Methods

GWs were first observed a decade ago and since then the LIGO–Virgo–KAGRA detectors have spotted GWs from hundreds of merging black holes and neutron stars, working in the 10 Hz–30 kHz range.

Researchers have also had some success at observing a GW background at nanohertz frequencies using pulsar timing arrays.

Unexplored Frequency Range

However, GWs have yet to be detected in the milli-Hz band, which should include signals from binary systems of white dwarfs, neutron stars, and stellar-mass black holes, many of which would emanate from the Milky Way.

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Author's summary: Researchers propose using optical cavities to detect low-frequency gravitational waves.

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Physics World Physics World — 2025-10-13