# A large scale passive laser gyroscope for Earth rotation sensing

## TL;DR

This paper presents a large-scale passive resonant gyroscope with high sensitivity for Earth rotation sensing, demonstrating improved performance and potential for geophysical applications.

## Contribution

Development of a 1m x 1m heterolithic passive resonant gyroscope with enhanced rotation sensitivity and stability for Earth rotation measurements.

## Key findings

- Achieved rotation resolution of ~2E-9 rad/s at 1000s integration
- Sensitivity of 2E-9 rad/s/rtHz in 5-100 Hz band
- Initial results show improved performance over previous PRGs

## Abstract

Earth rotation sensing has many applications in different disciplines, such as for the monitoring of ground motions, the establishment of UT1 and the test of the relativistic Lense-Thirring effect on the ground. We report the development of a 1 m*1 m heterolithic passive resonant gyroscope (PRG). By locking a pair of laser beams to adjacent modes of the square ring cavity in the clockwise and counter-clockwise directions, we achieve a rotation resolution of about 2E-9 rad/s at an integration time of 1000 s. The sensitivity of the PRG for rotations reaches a level of 2E-9 rad/s/rtHz in the 5-100~Hz region, currently limited by the detection noise, residual amplitude modulation and the mechanical instability of the cavity. Our initial results improve the reported rotation sensitivity of the PRGs and indicate that PRGs have a great potential for high-resolution Earth rotation sensing.