Giant 64 m² passive green laser gyroscope: solution in Earth rotation sensing and geophysical detection

Large-scale laser gyroscopes with high resolution are widely used in Earth rotation sensing and geophysical detection. We demonstrate a giant 64 m² green laser gyroscope in a passive running mode. By adopting a heterolithic architecture and using a 532 nm solid state laser as the light source, the gyroscope demonstrates a short wavelength, a large-scale factor, and currently the highest <i>Q</i>-factor of 6 × 10¹² among existing gyroscopes. A minimum sensitivity of 7×10^-11<i>r</i><i>a</i><i>d</i>/<i>s</i>/<i>H</i><i>z</i> is achieved, which is the best performance among passive ring gyroscopes (PRGs) to the best of our knowledge. This high sensitivity allows detection of terrestrial secondary microseismic signal at about 0.25 Hz, demonstrating the application value of large-scale PRGs in the field of geophysics. With a theoretical shot-noise limit of 1×10^-12<i>r</i><i>a</i><i>d</i>/<i>s</i>/<i>H</i><i>z</i>, the PRG offers a promising solution for future detection of Earth rotation with extreme sensitivity.