Speaker
Description
Seismic motion remains a major limitation for low-frequency gravitational-wave detection. Reaching the target ET-LF sensitivity requires substantial improvements to current isolation systems. One approach to enhance low-frequency seismic isolation relies on a combination of passive and active strategies. However, active isolation faces important limitations due to the sensing techniques used in feedback control. Conventional inertial sensors are sensitive to both translational and rotational motion, which complicates the interpretation of seismic signals and limits platform isolation performance in the sub-Hz frequency range, where both contributions are significant.
A promising solution to overcome this limitation is the combined use of rotation sensors and classical inertial sensors to measure low-frequency seismic motion. This approach enables the separation of translational and rotational components, allowing for more precise platform control. In this context, we investigate the use of fibre-optic gyroscopes, based on the Sagnac effect, which are inherently insensitive to translation. Achieving the required performance remains a key challenge, as the technical requirements for rotation sensing are particularly stringent. Our approach takes advantage of the scaling of the sensor’s sensitivity with the size of the optical path to reach significantly enhanced resolution. This work presents the foundations of this concept, with its associated challenges and opportunities. We also report initial results obtained with a reduced-scale prototype and discuss the prospects and anticipated performance of future large-scale implementations.