Large-Scale Passive Laser Gyroscope For Earth Rotation Sensing

Earth rotation sensing has many applications in different disciplines such as the monitoring of ground motions, the establishment of UT1, and the testing of the relativistic Lense-Thirring effect on the ground. We report the development of a 1 m x 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 2 x 10(-9) rad/s at an integration time of 1000 s. The sensitivity of the PRG for rotations reaches a level of 2 x 10(-9) rad/s/root Hz in the 5-100 Hz region, currently limited by the detection noise, residual amplitude modulation, and 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. (C) 2019 Optical Society of America